|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
|
|
|
EX(1P) POSIX Programmer's Manual EX(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
ex — text editor
ex [-rR] [-s|-v] [-c command] [-t tagstring] [-w size] [file...]
The ex utility is a line-oriented text editor. There are two
other modes of the editor—open and visual—in which screen-
oriented editing is available. This is described more fully by
the ex open and visual commands and in vi(1p).
If an operand is '-', the results are unspecified.
This section uses the term edit buffer to describe the current
working text. No specific implementation is implied by this term.
All editing changes are performed on the edit buffer, and no
changes to it shall affect any file until an editor command
writes the file.
Certain terminals do not have all the capabilities necessary to
support the complete ex definition, such as the full-screen
editing commands (visual mode or open mode). When these commands
cannot be supported on such terminals, this condition shall not
produce an error message such as ``not an editor command'' or
report a syntax error. The implementation may either accept the
commands and produce results on the screen that are the result of
an unsuccessful attempt to meet the requirements of this volume
of POSIX.1‐2017 or report an error describing the terminal-
related deficiency.
The ex utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines, except for
the unspecified usage of '-', and that '+' may be recognized as
an option delimiter as well as '-'.
The following options shall be supported:
-c command
Specify an initial command to be executed in the first
edit buffer loaded from an existing file (see the
EXTENDED DESCRIPTION section). Implementations may
support more than a single -c option. In such
implementations, the specified commands shall be
executed in the order specified on the command line.
-r Recover the named files (see the EXTENDED DESCRIPTION
section). Recovery information for a file shall be
saved during an editor or system crash (for example,
when the editor is terminated by a signal which the
editor can catch), or after the use of an ex preserve
command.
A crash in this context is an unexpected failure of the
system or utility that requires restarting the failed
system or utility. A system crash implies that any
utilities running at the time also crash. In the case
of an editor or system crash, the number of changes to
the edit buffer (since the most recent preserve
command) that will be recovered is unspecified.
If no file operands are given and the -t option is not
specified, all other options, the EXINIT variable, and
any .exrc files shall be ignored; a list of all
recoverable files available to the invoking user shall
be written, and the editor shall exit normally without
further action.
-R Set readonly edit option.
-s Prepare ex for batch use by taking the following
actions:
* Suppress writing prompts and informational (but not
diagnostic) messages.
* Ignore the value of TERM and any implementation
default terminal type and assume the terminal is a
type incapable of supporting open or visual modes;
see the visual command and the description of
vi(1p).
* Suppress the use of the EXINIT environment variable
and the reading of any .exrc file; see the EXTENDED
DESCRIPTION section.
* Suppress autoindentation, ignoring the value of the
autoindent edit option.
-t tagstring
Edit the file containing the specified tagstring; see
ctags(1p). The tags feature represented by -t
tagstring and the tag command is optional. It shall be
provided on any system that also provides a conforming
implementation of ctags; otherwise, the use of -t
produces undefined results. On any system, it shall be
an error to specify more than a single -t option.
-v Begin in visual mode (see vi(1p)).
-w size Set the value of the window editor option to size.
The following operand shall be supported:
file A pathname of a file to be edited.
The standard input consists of a series of commands and input
text, as described in the EXTENDED DESCRIPTION section. The
implementation may limit each line of standard input to a length
of {LINE_MAX}.
If the standard input is not a terminal device, it shall be as if
the -s option had been specified.
If a read from the standard input returns an error, or if the
editor detects an end-of-file condition from the standard input,
it shall be equivalent to a SIGHUP asynchronous event.
Input files shall be text files or files that would be text files
except for an incomplete last line that is not longer than
{LINE_MAX}-1 bytes in length and contains no NUL characters. By
default, any incomplete last line shall be treated as if it had a
trailing <newline>. The editing of other forms of files may
optionally be allowed by ex implementations.
The .exrc files and source files shall be text files consisting
of ex commands; see the EXTENDED DESCRIPTION section.
By default, the editor shall read lines from the files to be
edited without interpreting any of those lines as any form of
editor command.
The following environment variables shall affect the execution of
ex:
COLUMNS Override the system-selected horizontal screen size.
See the Base Definitions volume of POSIX.1‐2017,
Chapter 8, Environment Variables for valid values and
results when it is unset or null.
EXINIT Determine a list of ex commands that are executed on
editor start-up. See the EXTENDED DESCRIPTION section
for more details of the initialization phase.
HOME Determine a pathname of a directory that shall be
searched for an editor start-up file named .exrc; see
the EXTENDED DESCRIPTION section.
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_COLLATE
Determine the locale for the behavior of ranges,
equivalence classes, and multi-character collating
elements within regular expressions.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments and input files), the behavior
of character classes within regular expressions, the
classification of characters as uppercase or lowercase
letters, the case conversion of letters, and the
detection of word boundaries.
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
LINES Override the system-selected vertical screen size, used
as the number of lines in a screenful and the vertical
screen size in visual mode. See the Base Definitions
volume of POSIX.1‐2017, Chapter 8, Environment
Variables for valid values and results when it is unset
or null.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
PATH Determine the search path for the shell command
specified in the ex editor commands !, shell, read, and
write, and the open and visual mode command !; see the
description of command search and execution in Section
2.9.1.1, Command Search and Execution.
SHELL Determine the preferred command line interpreter for
use as the default value of the shell edit option.
TERM Determine the name of the terminal type. If this
variable is unset or null, an unspecified default
terminal type shall be used.
The following term is used in this and following sections to
specify command and asynchronous event actions:
complete write
A complete write is a write of the entire contents of
the edit buffer to a file of a type other than a
terminal device, or the saving of the edit buffer
caused by the user executing the ex preserve command.
Writing the contents of the edit buffer to a temporary
file that will be removed when the editor exits shall
not be considered a complete write.
The following actions shall be taken upon receipt of signals:
SIGINT If the standard input is not a terminal device, ex
shall not write the file or return to command or text
input mode, and shall exit with a non-zero exit status.
Otherwise, if executing an open or visual text input
mode command, ex in receipt of SIGINT shall behave
identically to its receipt of the <ESC> character.
Otherwise:
1. If executing an ex text input mode command, all
input lines that have been completely entered shall
be resolved into the edit buffer, and any partially
entered line shall be discarded.
2. If there is a currently executing command, it shall
be aborted and a message displayed. Unless
otherwise specified by the ex or vi command
descriptions, it is unspecified whether any lines
modified by the executing command appear modified,
or as they were before being modified by the
executing command, in the buffer.
If the currently executing command was a motion
command, its associated command shall be discarded.
3. If in open or visual command mode, the terminal
shall be alerted.
4. The editor shall then return to command mode.
SIGCONT The screen shall be refreshed if in open or visual
mode.
SIGHUP If the edit buffer has been modified since the last
complete write, ex shall attempt to save the edit
buffer so that it can be recovered later using the -r
option or the ex recover command. The editor shall not
write the file or return to command or text input mode,
and shall terminate with a non-zero exit status.
SIGTERM Refer to SIGHUP.
The action taken for all other signals is unspecified.
The standard output shall be used only for writing prompts to the
user, for informational messages, and for writing lines from the
file.
The standard error shall be used only for diagnostic messages.
The output from ex shall be text files.
Only the ex mode of the editor is described in this section. See
vi(1p) for additional editing capabilities available in ex.
When an error occurs, ex shall write a message. If the terminal
supports a standout mode (such as inverse video), the message
shall be written in standout mode. If the terminal does not
support a standout mode, and the edit option errorbells is set,
an alert action shall precede the error message.
By default, ex shall start in command mode, which shall be
indicated by a : prompt; see the prompt command. Text input mode
can be entered by the append, insert, or change commands; it can
be exited (and command mode re-entered) by typing a <period>
('.') alone at the beginning of a line.
Initialization in ex and vi
The following symbols are used in this and following sections to
specify locations in the edit buffer:
alternate and current pathnames
Two pathnames, named current and alternate, are maintained
by the editor. Any ex commands that take filenames as
arguments shall set them as follows:
1. If a file argument is specified to the ex edit, ex, or
recover commands, or if an ex tag command replaces the
contents of the edit buffer.
a. If the command replaces the contents of the edit
buffer, the current pathname shall be set to the
file argument or the file indicated by the tag, and
the alternate pathname shall be set to the previous
value of the current pathname.
b. Otherwise, the alternate pathname shall be set to
the file argument.
2. If a file argument is specified to the ex next command:
a. If the command replaces the contents of the edit
buffer, the current pathname shall be set to the
first file argument, and the alternate pathname
shall be set to the previous value of the current
pathname.
3. If a file argument is specified to the ex file command,
the current pathname shall be set to the file argument,
and the alternate pathname shall be set to the previous
value of the current pathname.
4. If a file argument is specified to the ex read and
write commands (that is, when reading or writing a
file, and not to the program named by the shell edit
option), or a file argument is specified to the ex xit
command:
a. If the current pathname has no value, the current
pathname shall be set to the file argument.
b. Otherwise, the alternate pathname shall be set to
the file argument.
If the alternate pathname is set to the previous value of
the current pathname when the current pathname had no
previous value, then the alternate pathname shall have no
value as a result.
current line
The line of the edit buffer referenced by the cursor. Each
command description specifies the current line after the
command has been executed, as the current line value. When
the edit buffer contains no lines, the current line shall
be zero; see Addressing in ex.
current column
The current display line column occupied by the cursor.
(The columns shall be numbered beginning at 1.) Each
command description specifies the current column after the
command has been executed, as the current column value.
This column is an ideal column that is remembered over the
lifetime of the editor. The actual display line column upon
which the cursor rests may be different from the current
column; see the cursor positioning discussion in Command
Descriptions in vi.
set to non-<blank>
A description for a current column value, meaning that the
current column shall be set to the last display line column
on which is displayed any part of the first non-<blank> of
the line. If the line has no non-<blank> non-<newline>
characters, the current column shall be set to the last
display line column on which is displayed any part of the
last non-<newline> character in the line. If the line is
empty, the current column shall be set to column position
1.
The length of lines in the edit buffer may be limited to
{LINE_MAX} bytes. In open and visual mode, the length of lines in
the edit buffer may be limited to the number of characters that
will fit in the display. If either limit is exceeded during
editing, an error message shall be written. If either limit is
exceeded by a line read in from a file, an error message shall be
written and the edit session may be terminated.
If the editor stops running due to any reason other than a user
command, and the edit buffer has been modified since the last
complete write, it shall be equivalent to a SIGHUP asynchronous
event. If the system crashes, it shall be equivalent to a SIGHUP
asynchronous event.
During initialization (before the first file is copied into the
edit buffer or any user commands from the terminal are processed)
the following shall occur:
1. If the environment variable EXINIT is set, the editor shall
execute the ex commands contained in that variable.
2. If the EXINIT variable is not set, and all of the following
are true:
a. The HOME environment variable is not null and not empty.
b. The file .exrc in the directory referred to by the HOME
environment variable:
i. Exists
ii. Is owned by the same user ID as the real user ID of
the process or the process has appropriate
privileges
iii. Is not writable by anyone other than the owner
the editor shall execute the ex commands contained in that
file.
3. If and only if all of the following are true:
a. The current directory is not referred to by the HOME
environment variable.
b. A command in the EXINIT environment variable or a command
in the .exrc file in the directory referred to by the
HOME environment variable sets the editor option exrc.
c. The .exrc file in the current directory:
i. Exists
ii. Is owned by the same user ID as the real user ID of
the process, or by one of a set of implementation-
defined user IDs
iii. Is not writable by anyone other than the owner
the editor shall attempt to execute the ex commands contained
in that file.
Lines in any .exrc file that are blank lines shall be ignored. If
any .exrc file exists, but is not read for ownership or
permission reasons, it shall be an error.
After the EXINIT variable and any .exrc files are processed, the
first file specified by the user shall be edited, as follows:
1. If the user specified the -t option, the effect shall be as
if the ex tag command was entered with the specified
argument, with the exception that if tag processing does not
result in a file to edit, the effect shall be as described in
step 3. below.
2. Otherwise, if the user specified any command line file
arguments, the effect shall be as if the ex edit command was
entered with the first of those arguments as its file
argument.
3. Otherwise, the effect shall be as if the ex edit command was
entered with a nonexistent filename as its file argument. It
is unspecified whether this action shall set the current
pathname. In an implementation where this action does not set
the current pathname, any editor command using the current
pathname shall fail until an editor command sets the current
pathname.
If the -r option was specified, the first time a file in the
initial argument list or a file specified by the -t option is
edited, if recovery information has previously been saved about
it, that information shall be recovered and the editor shall
behave as if the contents of the edit buffer have already been
modified. If there are multiple instances of the file to be
recovered, the one most recently saved shall be recovered, and an
informational message that there are previous versions of the
file that can be recovered shall be written. If no recovery
information about a file is available, an informational message
to this effect shall be written, and the edit shall proceed as
usual.
If the -c option was specified, the first time a file that
already exists (including a file that might not exist but for
which recovery information is available, when the -r option is
specified) replaces or initializes the contents of the edit
buffer, the current line shall be set to the last line of the
edit buffer, the current column shall be set to non-<blank>, and
the ex commands specified with the -c option shall be executed.
In this case, the current line and current column shall not be
set as described for the command associated with the replacement
or initialization of the edit buffer contents. However, if the -t
option or a tag command is associated with this action, the -c
option commands shall be executed and then the movement to the
tag shall be performed.
The current argument list shall initially be set to the filenames
specified by the user on the command line. If no filenames are
specified by the user, the current argument list shall be empty.
If the -t option was specified, it is unspecified whether any
filename resulting from tag processing shall be prepended to the
current argument list. In the case where the filename is added as
a prefix to the current argument list, the current argument list
reference shall be set to that filename. In the case where the
filename is not added as a prefix to the current argument list,
the current argument list reference shall logically be located
before the first of the filenames specified on the command line
(for example, a subsequent ex next command shall edit the first
filename from the command line). If the -t option was not
specified, the current argument list reference shall be to the
first of the filenames on the command line.
Addressing in ex
Addressing in ex relates to the current line and the current
column; the address of a line is its 1-based line number, the
address of a column is its 1-based count from the beginning of
the line. Generally, the current line is the last line affected
by a command. The current line number is the address of the
current line. In each command description, the effect of the
command on the current line number and the current column is
described.
Addresses are constructed as follows:
1. The character '.' (period) shall address the current line.
2. The character '$' shall address the last line of the edit
buffer.
3. The positive decimal number n shall address the nth line of
the edit buffer.
4. The address "'x" refers to the line marked with the mark name
character 'x', which shall be a lowercase letter from the
portable character set, the backquote character, or the
single-quote character. It shall be an error if the line that
was marked is not currently present in the edit buffer or the
mark has not been set. Lines can be marked with the ex mark
or k commands, or the vi m command.
5. A regular expression enclosed by <slash> characters ('/')
shall address the first line found by searching forwards from
the line following the current line toward the end of the
edit buffer and stopping at the first line for which the line
excluding the terminating <newline> matches the regular
expression. As stated in Regular Expressions in ex, an
address consisting of a null regular expression delimited by
<slash> characters ("//") shall address the next line for
which the line excluding the terminating <newline> matches
the last regular expression encountered. In addition, the
second <slash> can be omitted at the end of a command line.
If the wrapscan edit option is set, the search shall wrap
around to the beginning of the edit buffer and continue up to
and including the current line, so that the entire edit
buffer is searched. Within the regular expression, the
sequence "\/" shall represent a literal <slash> instead of
the regular expression delimiter.
6. A regular expression enclosed in <question-mark> characters
('?') shall address the first line found by searching
backwards from the line preceding the current line toward the
beginning of the edit buffer and stopping at the first line
for which the line excluding the terminating <newline>
matches the regular expression. An address consisting of a
null regular expression delimited by <question-mark>
characters ("??") shall address the previous line for which
the line excluding the terminating <newline> matches the last
regular expression encountered. In addition, the second
<question-mark> can be omitted at the end of a command line.
If the wrapscan edit option is set, the search shall wrap
around from the beginning of the edit buffer to the end of
the edit buffer and continue up to and including the current
line, so that the entire edit buffer is searched. Within the
regular expression, the sequence "\?" shall represent a
literal <question-mark> instead of the RE delimiter.
7. A <plus-sign> ('+') or a <hyphen-minus> ('-') followed by a
decimal number shall address the current line plus or minus
the number. A '+' or '-' not followed by a decimal number
shall address the current line plus or minus 1.
Addresses can be followed by zero or more address offsets,
optionally <blank>-separated. Address offsets are constructed as
follows:
1. A '+' or '-' immediately followed by a decimal number shall
add (subtract) the indicated number of lines to (from) the
address. A '+' or '-' not followed by a decimal number shall
add (subtract) 1 to (from) the address.
2. A decimal number shall add the indicated number of lines to
the address.
It shall not be an error for an intermediate address value to be
less than zero or greater than the last line in the edit buffer.
It shall be an error for the final address value to be less than
zero or greater than the last line in the edit buffer.
Commands take zero, one, or two addresses; see the descriptions
of 1addr and 2addr in Command Descriptions in ex. If more than
the required number of addresses are provided to a command that
requires zero addresses, it shall be an error. Otherwise, if more
than the required number of addresses are provided to a command,
the addresses specified first shall be evaluated and then
discarded until the maximum number of valid addresses remain.
Addresses shall be separated from each other by a <comma> (',')
or a <semicolon> (';'). If no address is specified before or
after a <comma> or <semicolon> separator, it shall be as if the
address of the current line was specified before or after the
separator. In the case of a <semicolon> separator, the current
line ('.') shall be set to the first address, and only then will
the next address be calculated. This feature can be used to
determine the starting line for forwards and backwards searches
(see rules 5. and 6.).
A <percent-sign> ('%') shall be equivalent to entering the two
addresses "1,$".
Any delimiting <blank> characters between addresses, address
separators, or address offsets shall be discarded.
Command Line Parsing in ex
The following symbol is used in this and following sections to
describe parsing behavior:
escape If a character is referred to as
``<backslash>-escaped'' or ``<control>‐V-escaped'', it
shall mean that the character acquired or lost a
special meaning by virtue of being preceded,
respectively, by a <backslash> or <control>‐V
character. Unless otherwise specified, the escaping
character shall be discarded at that time and shall not
be further considered for any purpose.
Command-line parsing shall be done in the following steps. For
each step, characters already evaluated shall be ignored; that
is, the phrase ``leading character'' refers to the next character
that has not yet been evaluated.
1. Leading <colon> characters shall be skipped.
2. Leading <blank> characters shall be skipped.
3. If the leading character is a double-quote character, the
characters up to and including the next
non-<backslash>-escaped <newline> shall be discarded, and any
subsequent characters shall be parsed as a separate command.
4. Leading characters that can be interpreted as addresses shall
be evaluated; see Addressing in ex.
5. Leading <blank> characters shall be skipped.
6. If the next character is a <vertical-line> character or a
<newline>:
a. If the next character is a <newline>:
i. If ex is in open or visual mode, the current line
shall be set to the last address specified, if any.
ii. Otherwise, if the last command was terminated by a
<vertical-line> character, no action shall be taken;
for example, the command "||<newline>" shall execute
two implied commands, not three.
iii. Otherwise, step 6.b. shall apply.
b. Otherwise, the implied command shall be the print
command. The last #, p, and l flags specified to any ex
command shall be remembered and shall apply to this
implied command. Executing the ex number, print, or list
command shall set the remembered flags to #, nothing, and
l, respectively, plus any other flags specified for that
execution of the number, print, or list command.
If ex is not currently performing a global or v command,
and no address or count is specified, the current line
shall be incremented by 1 before the command is executed.
If incrementing the current line would result in an
address past the last line in the edit buffer, the
command shall fail, and the increment shall not happen.
c. The <newline> or <vertical-line> character shall be
discarded and any subsequent characters shall be parsed
as a separate command.
7. The command name shall be comprised of the next character (if
the character is not alphabetic), or the next character and
any subsequent alphabetic characters (if the character is
alphabetic), with the following exceptions:
a. Commands that consist of any prefix of the characters in
the command name delete, followed immediately by any of
the characters 'l', 'p', '+', '-', or '#' shall be
interpreted as a delete command, followed by a <blank>,
followed by the characters that were not part of the
prefix of the delete command. The maximum number of
characters shall be matched to the command name delete;
for example, "del" shall not be treated as "de" followed
by the flag l.
b. Commands that consist of the character 'k', followed by a
character that can be used as the name of a mark, shall
be equivalent to the mark command followed by a <blank>,
followed by the character that followed the 'k'.
c. Commands that consist of the character 's', followed by
characters that could be interpreted as valid options to
the s command, shall be the equivalent of the s command,
without any pattern or replacement values, followed by a
<blank>, followed by the characters after the 's'.
8. The command name shall be matched against the possible
command names, and a command name that contains a prefix
matching the characters specified by the user shall be the
executed command. In the case of commands where the
characters specified by the user could be ambiguous, the
executed command shall be as follows:
┌────┬────────┬┬───┬───────┬┬───┬───────┐
│ a │ append ││n │ next ││t │ t │
│ c │ change ││p │ print ││u │ undo │
│ ch │ change ││pr │ print ││un │ undo │
│ e │ edit ││r │ read ││v │ v │
│ m │ move ││re │ read ││w │ write │
│ ma │ mark ││s │ s ││ │ │
└────┴────────┴┴───┴───────┴┴───┴───────┘
Implementation extensions with names causing similar
ambiguities shall not be checked for a match until all
possible matches for commands specified by POSIX.1‐2008 have
been checked.
9. If the command is a ! command, or if the command is a read
command followed by zero or more <blank> characters and a !,
or if the command is a write command followed by one or more
<blank> characters and a !, the rest of the command shall
include all characters up to a non-<backslash>-escaped
<newline>. The <newline> shall be discarded and any
subsequent characters shall be parsed as a separate ex
command.
10. Otherwise, if the command is an edit, ex, or next command, or
a visual command while in open or visual mode, the next part
of the command shall be parsed as follows:
a. Any '!' character immediately following the command
shall be skipped and be part of the command.
b. Any leading <blank> characters shall be skipped and be
part of the command.
c. If the next character is a '+', characters up to the
first non-<backslash>-escaped <newline> or
non-<backslash>-escaped <blank> shall be skipped and be
part of the command.
d. The rest of the command shall be determined by the steps
specified in paragraph 12.
11. Otherwise, if the command is a global, open, s, or v command,
the next part of the command shall be parsed as follows:
a. Any leading <blank> characters shall be skipped and be
part of the command.
b. If the next character is not an alphanumeric, double-
quote, <newline>, <backslash>, or <vertical-line>
character:
i. The next character shall be used as a command
delimiter.
ii. If the command is a global, open, or v command,
characters up to the first non-<backslash>-escaped
<newline>, or first non-<backslash>-escaped
delimiter character, shall be skipped and be part of
the command.
iii. If the command is an s command, characters up to the
first non-<backslash>-escaped <newline>, or second
non-<backslash>-escaped delimiter character, shall
be skipped and be part of the command.
c. If the command is a global or v command, characters up to
the first non-<backslash>-escaped <newline> shall be
skipped and be part of the command.
d. Otherwise, the rest of the command shall be determined by
the steps specified in paragraph 12.
12. Otherwise:
a. If the command was a map, unmap, abbreviate, or
unabbreviate command, characters up to the first
non-<control>‐V-escaped <newline>, <vertical-line>, or
double-quote character shall be skipped and be part of
the command.
b. Otherwise, characters up to the first
non-<backslash>-escaped <newline>, <vertical-line>, or
double-quote character shall be skipped and be part of
the command.
c. If the command was an append, change, or insert command,
and the step 12.b. ended at a <vertical-line> character,
any subsequent characters, up to the next
non-<backslash>-escaped <newline> shall be used as input
text to the command.
d. If the command was ended by a double-quote character, all
subsequent characters, up to the next
non-<backslash>-escaped <newline>, shall be discarded.
e. The terminating <newline> or <vertical-line> character
shall be discarded and any subsequent characters shall be
parsed as a separate ex command.
Command arguments shall be parsed as described by the Synopsis
and Description of each individual ex command. This parsing shall
not be <blank>-sensitive, except for the ! argument, which must
follow the command name without intervening <blank> characters,
and where it would otherwise be ambiguous. For example, count and
flag arguments need not be <blank>-separated because "d22p" is
not ambiguous, but file arguments to the ex next command must be
separated by one or more <blank> characters. Any <blank> in
command arguments for the abbreviate, unabbreviate, map, and
unmap commands can be <control>‐V-escaped, in which case the
<blank> shall not be used as an argument delimiter. Any <blank>
in the command argument for any other command can be
<backslash>-escaped, in which case that <blank> shall not be used
as an argument delimiter.
Within command arguments for the abbreviate, unabbreviate, map,
and unmap commands, any character can be <control>‐V-escaped.
All such escaped characters shall be treated literally and shall
have no special meaning. Within command arguments for all other
ex commands that are not regular expressions or replacement
strings, any character that would otherwise have a special
meaning can be <backslash>-escaped. Escaped characters shall be
treated literally, without special meaning as shell expansion
characters or '!', '%', and '#' expansion characters. See Regular
Expressions in ex and Replacement Strings in ex for descriptions
of command arguments that are regular expressions or replacement
strings.
Non-<backslash>-escaped '%' characters appearing in file
arguments to any ex command shall be replaced by the current
pathname; unescaped '#' characters shall be replaced by the
alternate pathname. It shall be an error if '%' or '#' characters
appear unescaped in an argument and their corresponding values
are not set.
Non-<backslash>-escaped '!' characters in the arguments to
either the ex ! command or the open and visual mode ! command,
or in the arguments to the ex read command, where the first
non-<blank> after the command name is a '!' character, or in the
arguments to the ex write command where the command name is
followed by one or more <blank> characters and the first
non-<blank> after the command name is a '!' character, shall be
replaced with the arguments to the last of those three commands
as they appeared after all unescaped '%', '#', and '!'
characters were replaced. It shall be an error if '!' characters
appear unescaped in one of these commands and there has been no
previous execution of one of these commands.
If an error occurs during the parsing or execution of an ex
command:
* An informational message to this effect shall be written.
Execution of the ex command shall stop, and the cursor (for
example, the current line and column) shall not be further
modified.
* If the ex command resulted from a map expansion, all
characters from that map expansion shall be discarded, except
as otherwise specified by the map command.
* Otherwise, if the ex command resulted from the processing of
an EXINIT environment variable, a .exrc file, a :source
command, a -c option, or a +command specified to an ex edit,
ex, next, or visual command, no further commands from the
source of the commands shall be executed.
* Otherwise, if the ex command resulted from the execution of a
buffer or a global or v command, no further commands caused
by the execution of the buffer or the global or v command
shall be executed.
* Otherwise, if the ex command was not terminated by a
<newline>, all characters up to and including the next
non-<backslash>-escaped <newline> shall be discarded.
Input Editing in ex
The following symbol is used in this and the following sections
to specify command actions:
word In the POSIX locale, a word consists of a maximal
sequence of letters, digits, and underscores, delimited
at both ends by characters other than letters, digits,
or underscores, or by the beginning or end of a line or
the edit buffer.
When accepting input characters from the user, in either ex
command mode or ex text input mode, ex shall enable canonical
mode input processing, as defined in the System Interfaces volume
of POSIX.1‐2017.
If in ex text input mode:
1. If the number edit option is set, ex shall prompt for input
using the line number that would be assigned to the line if
it is entered, in the format specified for the ex number
command.
2. If the autoindent edit option is set, ex shall prompt for
input using autoindent characters, as described by the
autoindent edit option. autoindent characters shall follow
the line number, if any.
If in ex command mode:
1. If the prompt edit option is set, input shall be prompted for
using a single ':' character; otherwise, there shall be no
prompt.
The input characters in the following sections shall have the
following effects on the input line.
Scroll
Synopsis:
eof
See the description of the stty eof character in stty(1p).
If in ex command mode:
If the eof character is the first character entered on the
line, the line shall be evaluated as if it contained two
characters: a <control>‐D and a <newline>.
Otherwise, the eof character shall have no special
meaning.
If in ex text input mode:
If the cursor follows an autoindent character, the
autoindent characters in the line shall be modified so
that a part of the next text input character will be
displayed on the first column in the line after the
previous shiftwidth edit option column boundary, and the
user shall be prompted again for input for the same line.
Otherwise, if the cursor follows a '0', which follows an
autoindent character, and the '0' was the previous text
input character, the '0' and all autoindent characters in
the line shall be discarded, and the user shall be
prompted again for input for the same line.
Otherwise, if the cursor follows a '^', which follows an
autoindent character, and the '^' was the previous text
input character, the '^' and all autoindent characters in
the line shall be discarded, and the user shall be
prompted again for input for the same line. In addition,
the autoindent level for the next input line shall be
derived from the same line from which the autoindent level
for the current input line was derived.
Otherwise, if there are no autoindent or text input
characters in the line, the eof character shall be
discarded.
Otherwise, the eof character shall have no special
meaning.
<newline>
Synopsis:
<newline>
<control>-J
If in ex command mode:
Cause the command line to be parsed; <control>‐J shall be
mapped to the <newline> for this purpose.
If in ex text input mode:
Terminate the current line. If there are no characters
other than autoindent characters on the line, all
characters on the line shall be discarded.
Prompt for text input on a new line after the current
line. If the autoindent edit option is set, an appropriate
number of autoindent characters shall be added as a prefix
to the line as described by the ex autoindent edit option.
<backslash>
Synopsis:
<backslash>
Allow the entry of a subsequent <newline> or <control>‐J as a
literal character, removing any special meaning that it may have
to the editor during text input mode. The <backslash> character
shall be retained and evaluated when the command line is parsed,
or retained and included when the input text becomes part of the
edit buffer.
<control>‐V
Synopsis:
<control>-V
Allow the entry of any subsequent character as a literal
character, removing any special meaning that it may have to the
editor during text input mode. The <control>‐V character shall be
discarded before the command line is parsed or the input text
becomes part of the edit buffer.
If the ``literal next'' functionality is performed by the
underlying system, it is implementation-defined whether a
character other than <control>‐V performs this function.
<control>‐W
Synopsis:
<control>-W
Discard the <control>‐W, and the word previous to it in the input
line, including any <blank> characters following the word and
preceding the <control>‐W. If the ``word erase'' functionality
is performed by the underlying system, it is implementation-
defined whether a character other than <control>‐W performs this
function.
Command Descriptions in ex
The following symbols are used in this section to represent
command modifiers. Some of these modifiers can be omitted, in
which case the specified defaults shall be used.
1addr A single line address, given in any of the forms
described in Addressing in ex; the default shall be the
current line ('.'), unless otherwise specified.
If the line address is zero, it shall be an error,
unless otherwise specified in the following command
descriptions.
If the edit buffer is empty, and the address is
specified with a command other than =, append, insert,
open, put, read, or visual, or the address is not zero,
it shall be an error.
2addr Two addresses specifying an inclusive range of lines.
If no addresses are specified, the default for 2addr
shall be the current line only (".,."), unless
otherwise specified in the following command
descriptions. If one address is specified, 2addr shall
specify that line only, unless otherwise specified in
the following command descriptions.
It shall be an error if the first address is greater
than the second address.
If the edit buffer is empty, and the two addresses are
specified with a command other than the !, write, wq,
or xit commands, or either address is not zero, it
shall be an error.
count A positive decimal number. If count is specified, it
shall be equivalent to specifying an additional address
to the command, unless otherwise specified by the
following command descriptions. The additional address
shall be equal to the last address specified to the
command (either explicitly or by default) plus count-1.
If this would result in an address greater than the
last line of the edit buffer, it shall be corrected to
equal the last line of the edit buffer.
flags One or more of the characters '+', '-', '#', 'p', or
'l' (ell). The flag characters can be
<blank>-separated, and in any order or combination. The
characters '#', 'p', and 'l' shall cause lines to be
written in the format specified by the print command
with the specified flags.
The lines to be written are as follows:
1. All edit buffer lines written during the execution
of the ex &, ~, list, number, open, print, s,
visual, and z commands shall be written as
specified by flags.
2. After the completion of an ex command with a flag
as an argument, the current line shall be written
as specified by flags, unless the current line was
the last line written by the command.
The characters '+' and '-' cause the value of the
current line after the execution of the ex command to
be adjusted by the offset address as described in
Addressing in ex. This adjustment shall occur before
the current line is written as described in 2. above.
The default for flags shall be none.
buffer One of a number of named areas for holding text. The
named buffers are specified by the alphanumeric
characters of the POSIX locale. There shall also be one
``unnamed'' buffer. When no buffer is specified for
editor commands that use a buffer, the unnamed buffer
shall be used. Commands that store text into buffers
shall store the text as it was before the command took
effect, and shall store text occurring earlier in the
file before text occurring later in the file,
regardless of how the text region was specified.
Commands that store text into buffers shall store the
text into the unnamed buffer as well as any specified
buffer.
In ex commands, buffer names are specified as the name
by itself. In open or visual mode commands the name is
preceded by a double-quote ('"') character.
If the specified buffer name is an uppercase character,
and the buffer contents are to be modified, the buffer
shall be appended to rather than being overwritten. If
the buffer is not being modified, specifying the buffer
name in lowercase and uppercase shall have identical
results.
There shall also be buffers named by the numbers 1
through 9. In open and visual mode, if a region of text
including characters from more than a single line is
being modified by the vi c or d commands, the motion
character associated with the c or d commands specifies
that the buffer text shall be in line mode, or the
commands %, `, /, ?, (, ), N, n, {, or } are used to
define a region of text for the c or d commands, the
contents of buffers 1 through 8 shall be moved into the
buffer named by the next numerically greater value, the
contents of buffer 9 shall be discarded, and the region
of text shall be copied into buffer 1. This shall be in
addition to copying the text into a user-specified
buffer or unnamed buffer, or both. Numeric buffers can
be specified as a source buffer for open and visual
mode commands; however, specifying a numeric buffer as
the write target of an open or visual mode command
shall have unspecified results.
The text of each buffer shall have the characteristic
of being in either line or character mode. Appending
text to a non-empty buffer shall set the mode to match
the characteristic of the text being appended.
Appending text to a buffer shall cause the creation of
at least one additional line in the buffer. All text
stored into buffers by ex commands shall be in line
mode. The ex commands that use buffers as the source of
text specify individually how buffers of different
modes are handled. Each open or visual mode command
that uses buffers for any purpose specifies
individually the mode of the text stored into the
buffer and how buffers of different modes are handled.
file Command text used to derive a pathname. The default
shall be the current pathname, as defined previously,
in which case, if no current pathname has yet been
established it shall be an error, except where
specifically noted in the individual command
descriptions that follow. If the command text contains
any of the characters '~', '{', '[', '*', '?', '$',
'"', backquote, single-quote, and <backslash>, it shall
be subjected to the process of ``shell expansions'', as
described below; if more than a single pathname results
and the command expects only one, it shall be an error.
The process of shell expansions in the editor shall be
done as follows. The ex utility shall pass two
arguments to the program named by the shell edit
option; the first shall be -c, and the second shall be
the string "echo" and the command text as a single
argument. The standard output and standard error of
that command shall replace the command text.
! A character that can be appended to the command name to
modify its operation, as detailed in the individual
command descriptions. With the exception of the ex
read, write, and ! commands, the '!' character shall
only act as a modifier if there are no <blank>
characters between it and the command name.
remembered search direction
The vi commands N and n begin searching in a forwards
or backwards direction in the edit buffer based on a
remembered search direction, which is initially unset,
and is set by the ex global, v, s, and tag commands,
and the vi / and ? commands.
Abbreviate
Synopsis:
ab[breviate][lhs rhs]
If lhs and rhs are not specified, write the current list of
abbreviations and do nothing more.
Implementations may restrict the set of characters accepted in
lhs or rhs, except that printable characters and <blank>
characters shall not be restricted. Additional restrictions shall
be implementation-defined.
In both lhs and rhs, any character may be escaped with a
<control>‐V, in which case the character shall not be used to
delimit lhs from rhs, and the escaping <control>‐V shall be
discarded.
In open and visual text input mode, if a non-word or <ESC>
character that is not escaped by a <control>‐V character is
entered after a word character, a check shall be made for a set
of characters matching lhs, in the text input entered during this
command. If it is found, the effect shall be as if rhs was
entered instead of lhs.
The set of characters that are checked is defined as follows:
1. If there are no characters inserted before the word and non-
word or <ESC> characters that triggered the check, the set of
characters shall consist of the word character.
2. If the character inserted before the word and non-word or
<ESC> characters that triggered the check is a word
character, the set of characters shall consist of the
characters inserted immediately before the triggering
characters that are word characters, plus the triggering word
character.
3. If the character inserted before the word and non-word or
<ESC> characters that triggered the check is not a word
character, the set of characters shall consist of the
characters that were inserted before the triggering
characters that are neither <blank> characters nor word
characters, plus the triggering word character.
It is unspecified whether the lhs argument entered for the ex
abbreviate and unabbreviate commands is replaced in this fashion.
Regardless of whether or not the replacement occurs, the effect
of the command shall be as if the replacement had not occurred.
Current line: Unchanged.
Current column: Unchanged.
Append
Synopsis:
[1addr] a[ppend][!]
Enter ex text input mode; the input text shall be placed after
the specified line. If line zero is specified, the text shall be
placed at the beginning of the edit buffer.
This command shall be affected by the number and autoindent edit
options; following the command name with '!' shall cause the
autoindent edit option setting to be toggled for the duration of
this command only.
Current line: Set to the last input line; if no lines were input,
set to the specified line, or to the first line of the edit
buffer if a line of zero was specified, or zero if the edit
buffer is empty.
Current column: Set to non-<blank>.
Arguments
Synopsis:
ar[gs]
Write the current argument list, with the current argument-list
entry, if any, between '[' and ']' characters.
Current line: Unchanged.
Current column: Unchanged.
Change
Synopsis:
[2addr] c[hange][!][count]
Enter ex text input mode; the input text shall replace the
specified lines. The specified lines shall be copied into the
unnamed buffer, which shall become a line mode buffer.
This command shall be affected by the number and autoindent edit
options; following the command name with '!' shall cause the
autoindent edit option setting to be toggled for the duration of
this command only.
Current line: Set to the last input line; if no lines were input,
set to the line before the first address, or to the first line of
the edit buffer if there are no lines preceding the first
address, or to zero if the edit buffer is empty.
Current column: Set to non-<blank>.
Change Directory
Synopsis:
chd[ir][!][directory]
cd[!][directory]
Change the current working directory to directory.
If no directory argument is specified, and the HOME environment
variable is set to a non-null and non-empty value, directory
shall default to the value named in the HOME environment
variable. If the HOME environment variable is empty or is
undefined, the default value of directory is implementation-
defined.
If no '!' is appended to the command name, and the edit buffer
has been modified since the last complete write, and the current
pathname does not begin with a '/', it shall be an error.
Current line: Unchanged.
Current column: Unchanged.
Copy
Synopsis:
[2addr] co[py] 1addr [flags]
[2addr] t 1addr [flags]
Copy the specified lines after the specified destination line;
line zero specifies that the lines shall be placed at the
beginning of the edit buffer.
Current line: Set to the last line copied.
Current column: Set to non-<blank>.
Delete
Synopsis:
[2addr] d[elete][buffer][count][flags]
Delete the specified lines into a buffer (defaulting to the
unnamed buffer), which shall become a line-mode buffer.
Flags can immediately follow the command name; see Command Line
Parsing in ex.
Current line: Set to the line following the deleted lines, or to
the last line in the edit buffer if that line is past the end of
the edit buffer, or to zero if the edit buffer is empty.
Current column: Set to non-<blank>.
Edit
Synopsis:
e[dit][!][+command][file]
ex[!][+command][file]
If no '!' is appended to the command name, and the edit buffer
has been modified since the last complete write, it shall be an
error.
If file is specified, replace the current contents of the edit
buffer with the current contents of file, and set the current
pathname to file. If file is not specified, replace the current
contents of the edit buffer with the current contents of the file
named by the current pathname. If for any reason the current
contents of the file cannot be accessed, the edit buffer shall be
empty.
The +command option shall be <blank>-delimited; <blank>
characters within the +command can be escaped by preceding them
with a <backslash> character. The +command shall be interpreted
as an ex command immediately after the contents of the edit
buffer have been replaced and the current line and column have
been set.
If the edit buffer is empty:
Current line: Set to 0.
Current column: Set to 1.
Otherwise, if executed while in ex command mode or if the
+command argument is specified:
Current line: Set to the last line of the edit buffer.
Current column: Set to non-<blank>.
Otherwise, if file is omitted or results in the current pathname:
Current line: Set to the first line of the edit buffer.
Current column: Set to non-<blank>.
Otherwise, if file is the same as the last file edited, the line
and column shall be set as follows; if the file was previously
edited, the line and column may be set as follows:
Current line: Set to the last value held when that file was last
edited. If this value is not a valid line in the new edit buffer,
set to the first line of the edit buffer.
Current column: If the current line was set to the last value
held when the file was last edited, set to the last value held
when the file was last edited. Otherwise, or if the last value
is not a valid column in the new edit buffer, set to non-<blank>.
Otherwise:
Current line: Set to the first line of the edit buffer.
Current column: Set to non-<blank>.
File
Synopsis:
f[ile][file]
If a file argument is specified, the alternate pathname shall be
set to the current pathname, and the current pathname shall be
set to file.
Write an informational message. If the file has a current
pathname, it shall be included in this message; otherwise, the
message shall indicate that there is no current pathname. If the
edit buffer contains lines, the current line number and the
number of lines in the edit buffer shall be included in this
message; otherwise, the message shall indicate that the edit
buffer is empty. If the edit buffer has been modified since the
last complete write, this fact shall be included in this message.
If the readonly edit option is set, this fact shall be included
in this message. The message may contain other unspecified
information.
Current line: Unchanged.
Current column: Unchanged.
Global
Synopsis:
[2addr] g[lobal] /pattern/ [commands]
[2addr] v /pattern/ [commands]
The optional '!' character after the global command shall be the
same as executing the v command.
If pattern is empty (for example, "//") or not specified, the
last regular expression used in the editor command shall be used
as the pattern. The pattern can be delimited by <slash>
characters (shown in the Synopsis), as well as any non-
alphanumeric or non-<blank> other than <backslash>, <vertical-
line>, <newline>, or double-quote.
If no lines are specified, the lines shall default to the entire
file.
The global and v commands are logically two-pass operations.
First, mark the lines within the specified lines for which the
line excluding the terminating <newline> matches (global) or does
not match (v or global!) the specified pattern. Second, execute
the ex commands given by commands, with the current line ('.')
set to each marked line. If an error occurs during this process,
or the contents of the edit buffer are replaced (for example, by
the ex :edit command) an error message shall be written and no
more commands resulting from the execution of this command shall
be processed.
Multiple ex commands can be specified by entering multiple
commands on a single line using a <vertical-line> to delimit
them, or one per line, by escaping each <newline> with a
<backslash>.
If no commands are specified:
1. If in ex command mode, it shall be as if the print command
were specified.
2. Otherwise, no command shall be executed.
For the append, change, and insert commands, the input text shall
be included as part of the command, and the terminating <period>
can be omitted if the command ends the list of commands. The open
and visual commands can be specified as one of the commands, in
which case each marked line shall cause the editor to enter open
or visual mode. If open or visual mode is exited using the vi Q
command, the current line shall be set to the next marked line,
and open or visual mode reentered, until the list of marked lines
is exhausted.
The global, v, and undo commands cannot be used in commands.
Marked lines may be deleted by commands executed for lines
occurring earlier in the file than the marked lines. In this
case, no commands shall be executed for the deleted lines.
If the remembered search direction is not set, the global and v
commands shall set it to forward.
The autoprint and autoindent edit options shall be inhibited for
the duration of the g or v command.
Current line: If no commands executed, set to the last marked
line. Otherwise, as specified for the executed ex commands.
Current column: If no commands are executed, set to non-<blank>;
otherwise, as specified for the individual ex commands.
Insert
Synopsis:
[1addr] i[nsert][!]
Enter ex text input mode; the input text shall be placed before
the specified line. If the line is zero or 1, the text shall be
placed at the beginning of the edit buffer.
This command shall be affected by the number and autoindent edit
options; following the command name with '!' shall cause the
autoindent edit option setting to be toggled for the duration of
this command only.
Current line: Set to the last input line; if no lines were input,
set to the line before the specified line, or to the first line
of the edit buffer if there are no lines preceding the specified
line, or zero if the edit buffer is empty.
Current column: Set to non-<blank>.
Join
Synopsis:
[2addr] j[oin][!][count][flags]
If count is specified:
If no address was specified, the join command shall behave
as if 2addr were the current line and the current line
plus count (.,. + count).
If one address was specified, the join command shall
behave as if 2addr were the specified address and the
specified address plus count (addr,addr + count).
If two addresses were specified, the join command shall
behave as if an additional address, equal to the last
address plus count -1 (addr1,addr2,addr2 + count -1), was
specified.
If this would result in a second address greater than the
last line of the edit buffer, it shall be corrected to be
equal to the last line of the edit buffer.
If no count is specified:
If no address was specified, the join command shall behave
as if 2addr were the current line and the next line (.,.
+1).
If one address was specified, the join command shall
behave as if 2addr were the specified address and the next
line (addr,addr +1).
Join the text from the specified lines together into a single
line, which shall replace the specified lines.
If a '!' character is appended to the command name, the join
shall be without modification of any line, independent of the
current locale.
Otherwise, in the POSIX locale, set the current line to the first
of the specified lines, and then, for each subsequent line,
proceed as follows:
1. Discard leading <space> characters from the line to be
joined.
2. If the line to be joined is now empty, delete it, and skip
steps 3 through 5.
3. If the current line ends in a <blank>, or the first character
of the line to be joined is a ')' character, join the lines
without further modification.
4. If the last character of the current line is a '.', join the
lines with two <space> characters between them.
5. Otherwise, join the lines with a single <space> between them.
Current line: Set to the first line specified.
Current column: Set to non-<blank>.
List
Synopsis:
[2addr] l[ist][count][flags]
This command shall be equivalent to the ex command:
[2addr] p[rint][count] l[flags]
See Print.
Map
Synopsis:
map[!][lhs rhs]
If lhs and rhs are not specified:
1. If '!' is specified, write the current list of text input
mode maps.
2. Otherwise, write the current list of command mode maps.
3. Do nothing more.
Implementations may restrict the set of characters accepted in
lhs or rhs, except that printable characters and <blank>
characters shall not be restricted. Additional restrictions shall
be implementation-defined. In both lhs and rhs, any character can
be escaped with a <control>‐V, in which case the character shall
not be used to delimit lhs from rhs, and the escaping <control>‐V
shall be discarded.
If the character '!' is appended to the map command name, the
mapping shall be effective during open or visual text input mode
rather than open or visual command mode. This allows lhs to have
two different map definitions at the same time: one for command
mode and one for text input mode.
For command mode mappings:
When the lhs is entered as any part of a vi command in
open or visual mode (but not as part of the arguments to
the command), the action shall be as if the corresponding
rhs had been entered.
If any character in the command, other than the first, is
escaped using a <control>‐V character, that character
shall not be part of a match to an lhs.
It is unspecified whether implementations shall support
map commands where the lhs is more than a single character
in length, where the first character of the lhs is
printable.
If lhs contains more than one character and the first
character is '#', followed by a sequence of digits
corresponding to a numbered function key, then when this
function key is typed it shall be mapped to rhs.
Characters other than digits following a '#' character
also represent the function key named by the characters in
the lhs following the '#' and may be mapped to rhs. It is
unspecified how function keys are named or what function
keys are supported.
For text input mode mappings:
When the lhs is entered as any part of text entered in
open or visual text input modes, the action shall be as if
the corresponding rhs had been entered.
If any character in the input text is escaped using a
<control>‐V character, that character shall not be part of
a match to an lhs.
It is unspecified whether the lhs text entered for
subsequent map or unmap commands is replaced with the rhs
text for the purposes of the screen display; regardless of
whether or not the display appears as if the corresponding
rhs text was entered, the effect of the command shall be
as if the lhs text was entered.
If only part of the lhs is entered, it is unspecified how long
the editor will wait for additional, possibly matching characters
before treating the already entered characters as not matching
the lhs.
The rhs characters shall themselves be subject to remapping,
unless otherwise specified by the remap edit option, except that
if the characters in lhs occur as prefix characters in rhs, those
characters shall not be remapped.
On block-mode terminals, the mapping need not occur immediately
(for example, it may occur after the terminal transmits a group
of characters to the system), but it shall achieve the same
results as if it occurred immediately.
Current line: Unchanged.
Current column: Unchanged.
Mark
Synopsis:
[1addr] ma[rk] character
[1addr] k character
Implementations shall support character values of a single
lowercase letter of the POSIX locale and the backquote and
single-quote characters; support of other characters is
implementation-defined.
If executing the vi m command, set the specified mark to the
current line and 1-based numbered character referenced by the
current column, if any; otherwise, column position 1.
Otherwise, set the specified mark to the specified line and
1-based numbered first non-<blank> non-<newline> in the line, if
any; otherwise, the last non-<newline> in the line, if any;
otherwise, column position 1.
The mark shall remain associated with the line until the mark is
reset or the line is deleted. If a deleted line is restored by a
subsequent undo command, any marks previously associated with the
line, which have not been reset, shall be restored as well. Any
use of a mark not associated with a current line in the edit
buffer shall be an error.
The marks ` and ' shall be set as described previously,
immediately before the following events occur in the editor:
1. The use of '$' as an ex address
2. The use of a positive decimal number as an ex address
3. The use of a search command as an ex address
4. The use of a mark reference as an ex address
5. The use of the following open and visual mode commands:
<control>‐], %, (, ), [, ], {, }
6. The use of the following open and visual mode commands: ', G,
H, L, M, z if the current line will change as a result of the
command
7. The use of the open and visual mode commands: /, ?, N, `, n
if the current line or column will change as a result of the
command
8. The use of the ex mode commands: z, undo, global, v
For rules 1., 2., 3., and 4., the ` and ' marks shall not be set
if the ex command is parsed as specified by rule 6.a. in Command
Line Parsing in ex.
For rules 5., 6., and 7., the ` and ' marks shall not be set if
the commands are used as motion commands in open and visual mode.
For rules 1., 2., 3., 4., 5., 6., 7., and 8., the ` and ' marks
shall not be set if the command fails.
The ` and ' marks shall be set as described previously, each time
the contents of the edit buffer are replaced (including the
editing of the initial buffer), if in open or visual mode, or if
in ex mode and the edit buffer is not empty, before any commands
or movements (including commands or movements specified by the -c
or -t options or the +command argument) are executed on the edit
buffer. If in open or visual mode, the marks shall be set as if
executing the vi m command; otherwise, as if executing the ex
mark command.
When changing from ex mode to open or visual mode, if the ` and '
marks are not already set, the ` and ' marks shall be set as
described previously.
Current line: Unchanged.
Current column: Unchanged.
Move
Synopsis:
[2addr] m[ove] 1addr [flags]
Move the specified lines after the specified destination line. A
destination of line zero specifies that the lines shall be placed
at the beginning of the edit buffer. It shall be an error if the
destination line is within the range of lines to be moved.
Current line: Set to the last of the moved lines.
Current column: Set to non-<blank>.
Next
Synopsis:
n[ext][!][+command][file ...]
If no '!' is appended to the command name, and the edit buffer
has been modified since the last complete write, it shall be an
error, unless the file is successfully written as specified by
the autowrite option.
If one or more files is specified:
1. Set the argument list to the specified filenames.
2. Set the current argument list reference to be the first entry
in the argument list.
3. Set the current pathname to the first filename specified.
Otherwise:
1. It shall be an error if there are no more filenames in the
argument list after the filename currently referenced.
2. Set the current pathname and the current argument list
reference to the filename after the filename currently
referenced in the argument list.
Replace the contents of the edit buffer with the contents of the
file named by the current pathname. If for any reason the
contents of the file cannot be accessed, the edit buffer shall be
empty.
This command shall be affected by the autowrite and writeany edit
options.
The +command option shall be <blank>-delimited; <blank>
characters can be escaped by preceding them with a <backslash>
character. The +command shall be interpreted as an ex command
immediately after the contents of the edit buffer have been
replaced and the current line and column have been set.
Current line: Set as described for the edit command.
Current column: Set as described for the edit command.
Number
Synopsis:
[2addr] nu[mber][count][flags]
[2addr] #[count][flags]
These commands shall be equivalent to the ex command:
[2addr] p[rint][count] #[flags]
See Print.
Open
Synopsis:
[1addr] o[pen] /pattern/ [flags]
This command need not be supported on block-mode terminals or
terminals with insufficient capabilities. If standard input,
standard output, or standard error are not terminal devices, the
results are unspecified.
Enter open mode.
The trailing delimiter can be omitted from pattern at the end of
the command line. If pattern is empty (for example, "//") or not
specified, the last regular expression used in the editor shall
be used as the pattern. The pattern can be delimited by <slash>
characters (shown in the Synopsis), as well as any alphanumeric,
or non-<blank> other than <backslash>, <vertical-line>,
<newline>, or double-quote.
Current line: Set to the specified line.
Current column: Set to non-<blank>.
Preserve
Synopsis:
pre[serve]
Save the edit buffer in a form that can later be recovered by
using the -r option or by using the ex recover command. After the
file has been preserved, a mail message shall be sent to the
user. This message shall be readable by invoking the mailx
utility. The message shall contain the name of the file, the time
of preservation, and an ex command that could be used to recover
the file. Additional information may be included in the mail
message.
Current line: Unchanged.
Current column: Unchanged.
Print
Synopsis:
[2addr] p[rint][count][flags]
Write the addressed lines. The behavior is unspecified if the
number of columns on the display is less than the number of
columns required to write any single character in the lines being
written.
Non-printable characters, except for the <tab>, shall be written
as implementation-defined multi-character sequences.
If the # flag is specified or the number edit option is set, each
line shall be preceded by its line number in the following
format:
"%6d ", <line number>
If the l flag is specified or the list edit option is set:
1. The characters listed in the Base Definitions volume of
POSIX.1‐2017, Table 5-1, Escape Sequences and Associated
Actions shall be written as the corresponding escape
sequence.
2. Non-printable characters not in the Base Definitions volume
of POSIX.1‐2017, Table 5-1, Escape Sequences and Associated
Actions shall be written as one three-digit octal number
(with a preceding <backslash>) for each byte in the character
(most significant byte first).
3. The end of each line shall be marked with a '$', and literal
'$' characters within the line shall be written with a
preceding <backslash>.
Long lines shall be folded; the length at which folding occurs is
unspecified, but should be appropriate for the output terminal,
considering the number of columns of the terminal.
If a line is folded, and the l flag is not specified and the list
edit option is not set, it is unspecified whether a multi-column
character at the folding position is separated; it shall not be
discarded.
Current line: Set to the last written line.
Current column: Unchanged if the current line is unchanged;
otherwise, set to non-<blank>.
Put
Synopsis:
[1addr] pu[t][buffer]
Append text from the specified buffer (by default, the unnamed
buffer) to the specified line; line zero specifies that the text
shall be placed at the beginning of the edit buffer. Each portion
of a line in the buffer shall become a new line in the edit
buffer, regardless of the mode of the buffer.
Current line: Set to the last line entered into the edit buffer.
Current column: Set to non-<blank>.
Quit
Synopsis:
q[uit][!]
If no '!' is appended to the command name:
1. If the edit buffer has been modified since the last complete
write, it shall be an error.
2. If there are filenames in the argument list after the
filename currently referenced, and the last command was not a
quit, wq, xit, or ZZ (see Exit) command, it shall be an
error.
Otherwise, terminate the editing session.
Read
Synopsis:
[1addr] r[ead][!][file]
If '!' is not the first non-<blank> to follow the command name,
a copy of the specified file shall be appended into the edit
buffer after the specified line; line zero specifies that the
copy shall be placed at the beginning of the edit buffer. The
number of lines and bytes read shall be written. If no file is
named, the current pathname shall be the default. If there is no
current pathname, then file shall become the current pathname. If
there is no current pathname or file operand, it shall be an
error. Specifying a file that is not of type regular shall have
unspecified results.
Otherwise, if file is preceded by '!', the rest of the line after
the '!' shall have '%', '#', and '!' characters expanded as
described in Command Line Parsing in ex.
The ex utility shall then pass two arguments to the program named
by the shell edit option; the first shall be -c and the second
shall be the expanded arguments to the read command as a single
argument. The standard input of the program shall be set to the
standard input of the ex program when it was invoked. The
standard error and standard output of the program shall be
appended into the edit buffer after the specified line.
Each line in the copied file or program output (as delimited by
<newline> characters or the end of the file or output if it is
not immediately preceded by a <newline>), shall be a separate
line in the edit buffer. Any occurrences of <carriage-return> and
<newline> pairs in the output shall be treated as single
<newline> characters.
The special meaning of the '!' following the read command can be
overridden by escaping it with a <backslash> character.
Current line: If no lines are added to the edit buffer,
unchanged. Otherwise, if in open or visual mode, set to the first
line entered into the edit buffer. Otherwise, set to the last
line entered into the edit buffer.
Current column: Set to non-<blank>.
Recover
Synopsis:
rec[over][!] file
If no '!' is appended to the command name, and the edit buffer
has been modified since the last complete write, it shall be an
error.
If no file operand is specified, then the current pathname shall
be used. If there is no current pathname or file operand, it
shall be an error.
If no recovery information has previously been saved about file,
the recover command shall behave identically to the edit command,
and an informational message to this effect shall be written.
Otherwise, set the current pathname to file, and replace the
current contents of the edit buffer with the recovered contents
of file. If there are multiple instances of the file to be
recovered, the one most recently saved shall be recovered, and an
informational message that there are previous versions of the
file that can be recovered shall be written. The editor shall
behave as if the contents of the edit buffer have already been
modified.
Current file: Set as described for the edit command.
Current column: Set as described for the edit command.
Rewind
Synopsis:
rew[ind][!]
If no '!' is appended to the command name, and the edit buffer
has been modified since the last complete write, it shall be an
error, unless the file is successfully written as specified by
the autowrite option.
If the argument list is empty, it shall be an error.
The current argument list reference and the current pathname
shall be set to the first filename in the argument list.
Replace the contents of the edit buffer with the contents of the
file named by the current pathname. If for any reason the
contents of the file cannot be accessed, the edit buffer shall be
empty.
This command shall be affected by the autowrite and writeany edit
options.
Current line: Set as described for the edit command.
Current column: Set as described for the edit command.
Set
Synopsis:
se[t][option[=[value]] ...][nooption ...][option? ...][all]
When no arguments are specified, write the value of the term edit
option and those options whose values have been changed from the
default settings; when the argument all is specified, write all
of the option values.
Giving an option name followed by the character '?' shall cause
the current value of that option to be written. The '?' can be
separated from the option name by zero or more <blank>
characters. The '?' shall be necessary only for Boolean valued
options. Boolean options can be given values by the form set
option to turn them on or set nooption to turn them off; string
and numeric options can be assigned by the form set option=value.
Any <blank> characters in strings can be included as is by
preceding each <blank> with an escaping <backslash>. More than
one option can be set or listed by a single set command by
specifying multiple arguments, each separated from the next by
one or more <blank> characters.
See Edit Options in ex for details about specific options.
Current line: Unchanged.
Current column: Unchanged.
Shell
Synopsis:
sh[ell]
Invoke the program named in the shell edit option with the single
argument -i (interactive mode). Editing shall be resumed when the
program exits.
Current line: Unchanged.
Current column: Unchanged.
Source
Synopsis:
so[urce] file
Read and execute ex commands from file. Lines in the file that
are blank lines shall be ignored.
Current line: As specified for the individual ex commands.
Current column: As specified for the individual ex commands.
Substitute
Synopsis:
[2addr] s[ubstitute][/pattern/repl/[options][count][flags]]
[2addr] &[options][count][flags]]
[2addr] ~[options][count][flags]]
Replace the first instance of the pattern pattern by the string
repl on each specified line. (See Regular Expressions in ex and
Replacement Strings in ex.) Any non-alphabetic, non-<blank>
delimiter other than <backslash>, '|', <newline>, or double-quote
can be used instead of '/'. <backslash> characters can be used
to escape delimiters, <backslash> characters, and other special
characters.
The trailing delimiter can be omitted from pattern or from repl
at the end of the command line. If both pattern and repl are not
specified or are empty (for example, "//"), the last s command
shall be repeated. If only pattern is not specified or is empty,
the last regular expression used in the editor shall be used as
the pattern. If only repl is not specified or is empty, the
pattern shall be replaced by nothing. If the entire replacement
pattern is '%', the last replacement pattern to an s command
shall be used.
Entering a <carriage-return> in repl (which requires an escaping
<backslash> in ex mode and an escaping <control>‐V in open or vi
mode) shall split the line at that point, creating a new line in
the edit buffer. The <carriage-return> shall be discarded.
If options includes the letter 'g' (global), all non-overlapping
instances of the pattern in the line shall be replaced.
If options includes the letter 'c' (confirm), then before each
substitution the line shall be written; the written line shall
reflect all previous substitutions. On the following line,
<space> characters shall be written beneath the characters from
the line that are before the pattern to be replaced, and '^'
characters written beneath the characters included in the pattern
to be replaced. The ex utility shall then wait for a response
from the user. An affirmative response shall cause the
substitution to be done, while any other input shall not make the
substitution. An affirmative response shall consist of a line
with the affirmative response (as defined by the current locale)
at the beginning of the line. This line shall be subject to
editing in the same way as the ex command line.
If interrupted (see the ASYNCHRONOUS EVENTS section), any
modifications confirmed by the user shall be preserved in the
edit buffer after the interrupt.
If the remembered search direction is not set, the s command
shall set it to forward.
In the second Synopsis, the & command shall repeat the previous
substitution, as if the & command were replaced by:
s/pattern/repl/
where pattern and repl are as specified in the previous s, &, or
~ command.
In the third Synopsis, the ~ command shall repeat the previous
substitution, as if the '~' were replaced by:
s/pattern/repl/
where pattern shall be the last regular expression specified to
the editor, and repl shall be from the previous substitution
(including & and ~) command.
These commands shall be affected by the LC_MESSAGES environment
variable.
Current line: Set to the last line in which a substitution
occurred, or, unchanged if no substitution occurred.
Current column: Set to non-<blank>.
Suspend
Synopsis:
su[spend][!]
st[op][!]
Allow control to return to the invoking process; ex shall suspend
itself as if it had received the SIGTSTP signal. The suspension
shall occur only if job control is enabled in the invoking shell
(see the description of set -m).
These commands shall be affected by the autowrite and writeany
edit options.
The current susp character (see stty(1p)) shall be equivalent to
the suspend command.
Tag
Synopsis:
ta[g][!] tagstring
The results are unspecified if the format of a tags file is not
as specified by the ctags utility (see ctags(1p)) description.
The tag command shall search for tagstring in the tag files
referred to by the tag edit option, in the order they are
specified, until a reference to tagstring is found. Files shall
be searched from beginning to end. If no reference is found, it
shall be an error and an error message to this effect shall be
written. If the reference is not found, or if an error occurs
while processing a file referred to in the tag edit option, it
shall be an error, and an error message shall be written at the
first occurrence of such an error.
Otherwise, if the tags file contained a pattern, the pattern
shall be treated as a regular expression used in the editor; for
example, for the purposes of the s command.
If the tagstring is in a file with a different name than the
current pathname, set the current pathname to the name of that
file, and replace the contents of the edit buffer with the
contents of that file. In this case, if no '!' is appended to
the command name, and the edit buffer has been modified since the
last complete write, it shall be an error, unless the file is
successfully written as specified by the autowrite option.
This command shall be affected by the autowrite, tag, taglength,
and writeany edit options.
Current line: If the tags file contained a line number, set to
that line number. If the line number is larger than the last line
in the edit buffer, an error message shall be written and the
current line shall be set as specified for the edit command.
If the tags file contained a pattern, set to the first occurrence
of the pattern in the file. If no matching pattern is found, an
error message shall be written and the current line shall be set
as specified for the edit command.
Current column: If the tags file contained a line-number
reference and that line-number was not larger than the last line
in the edit buffer, or if the tags file contained a pattern and
that pattern was found, set to non-<blank>. Otherwise, set as
specified for the edit command.
Unabbreviate
Synopsis:
una[bbrev] lhs
If lhs is not an entry in the current list of abbreviations (see
Abbreviate), it shall be an error. Otherwise, delete lhs from the
list of abbreviations.
Current line: Unchanged.
Current column: Unchanged.
Undo
Synopsis:
u[ndo]
Reverse the changes made by the last command that modified the
contents of the edit buffer, including undo. For this purpose,
the global, v, open, and visual commands, and commands resulting
from buffer executions and mapped character expansions, are
considered single commands.
If no action that can be undone preceded the undo command, it
shall be an error.
If the undo command restores lines that were marked, the mark
shall also be restored unless it was reset subsequent to the
deletion of the lines.
Current line:
1. If lines are added or changed in the file, set to the first
line added or changed.
2. Set to the line before the first line deleted, if it exists.
3. Set to 1 if the edit buffer is not empty.
4. Set to zero.
Current column: Set to non-<blank>.
Unmap
Synopsis:
unm[ap][!] lhs
If '!' is appended to the command name, and if lhs is not an
entry in the list of text input mode map definitions, it shall be
an error. Otherwise, delete lhs from the list of text input mode
map definitions.
If no '!' is appended to the command name, and if lhs is not an
entry in the list of command mode map definitions, it shall be an
error. Otherwise, delete lhs from the list of command mode map
definitions.
Current line: Unchanged.
Current column: Unchanged.
Version
Synopsis:
ve[rsion]
Write a message containing version information for the editor.
The format of the message is unspecified.
Current line: Unchanged.
Current column: Unchanged.
Visual
Synopsis:
[1addr] vi[sual][type][count][flags]
If ex is currently in open or visual mode, the Synopsis and
behavior of the visual command shall be the same as the edit
command, as specified by Edit.
Otherwise, this command need not be supported on block-mode
terminals or terminals with insufficient capabilities. If
standard input, standard output, or standard error are not
terminal devices, the results are unspecified.
If count is specified, the value of the window edit option shall
be set to count (as described in window). If the '^' type
character was also specified, the window edit option shall be set
before being used by the type character.
Enter visual mode. If type is not specified, it shall be as if a
type of '+' was specified. The type shall cause the following
effects:
+ Place the beginning of the specified line at the top of the
display.
- Place the end of the specified line at the bottom of the
display.
. Place the beginning of the specified line in the middle of
the display.
^ If the specified line is less than or equal to the value of
the window edit option, set the line to 1; otherwise,
decrement the line by the value of the window edit option
minus 1. Place the beginning of this line as close to the
bottom of the displayed lines as possible, while still
displaying the value of the window edit option number of
lines.
Current line: Set to the specified line.
Current column: Set to non-<blank>.
Write
Synopsis:
[2addr] w[rite][!][>>][file]
[2addr] w[rite][!][file]
[2addr] wq[!][>>][file]
If no lines are specified, the lines shall default to the entire
file.
The command wq shall be equivalent to a write command followed by
a quit command; wq! shall be equivalent to write! followed by
quit. In both cases, if the write command fails, the quit shall
not be attempted.
If the command name is not followed by one or more <blank>
characters, or file is not preceded by a '!' character, the
write shall be to a file.
1. If the >> argument is specified, and the file already exists,
the lines shall be appended to the file instead of replacing
its contents. If the >> argument is specified, and the file
does not already exist, it is unspecified whether the write
shall proceed as if the >> argument had not been specified or
if the write shall fail.
2. If the readonly edit option is set (see readonly), the write
shall fail.
3. If file is specified, and is not the current pathname, and
the file exists, the write shall fail.
4. If file is not specified, the current pathname shall be used.
If there is no current pathname, the write command shall
fail.
5. If the current pathname is used, and the current pathname has
been changed by the file or read commands, and the file
exists, the write shall fail. If the write is successful,
subsequent writes shall not fail for this reason (unless the
current pathname is changed again).
6. If the whole edit buffer is not being written, and the file
to be written exists, the write shall fail.
For rules 1., 2., 3., and 5., the write can be forced by
appending the character '!' to the command name.
For rules 2., 3., and 5., the write can be forced by setting the
writeany edit option.
Additional, implementation-defined tests may cause the write to
fail.
If the edit buffer is empty, a file without any contents shall be
written.
An informational message shall be written noting the number of
lines and bytes written.
Otherwise, if the command is followed by one or more <blank>
characters, and the file is preceded by '!', the rest of the line
after the '!' shall have '%', '#', and '!' characters expanded
as described in Command Line Parsing in ex.
The ex utility shall then pass two arguments to the program named
by the shell edit option; the first shall be -c and the second
shall be the expanded arguments to the write command as a single
argument. The specified lines shall be written to the standard
input of the command. The standard error and standard output of
the program, if any, shall be written as described for the print
command. If the last character in that output is not a <newline>,
a <newline> shall be written at the end of the output.
The special meaning of the '!' following the write command can
be overridden by escaping it with a <backslash> character.
Current line: Unchanged.
Current column: Unchanged.
Write and Exit
Synopsis:
[2addr] x[it][!][file]
If the edit buffer has not been modified since the last complete
write, xit shall be equivalent to the quit command, or if a '!'
is appended to the command name, to quit!.
Otherwise, xit shall be equivalent to the wq command, or if a '!'
is appended to the command name, to wq!.
Current line: Unchanged.
Current column: Unchanged.
Yank
Synopsis:
[2addr] ya[nk][buffer][count]
Copy the specified lines to the specified buffer (by default, the
unnamed buffer), which shall become a line-mode buffer.
Current line: Unchanged.
Current column: Unchanged.
Adjust Window
Synopsis:
[1addr] z[!][type ...][count][flags]
If no line is specified, the current line shall be the default;
if type is omitted as well, the current line value shall first be
incremented by 1. If incrementing the current line would cause it
to be greater than the last line in the edit buffer, it shall be
an error.
If there are <blank> characters between the type argument and the
preceding z command name or optional '!' character, it shall be
an error.
If count is specified, the value of the window edit option shall
be set to count (as described in window). If count is omitted,
it shall default to 2 times the value of the scroll edit option,
or if ! was specified, the number of lines in the display minus
1.
If type is omitted, then count lines starting with the specified
line shall be written. Otherwise, count lines starting with the
line specified by the type argument shall be written.
The type argument shall change the lines to be written. The
possible values of type are as follows:
- The specified line shall be decremented by the following
value:
(((number of '-' characters) x count) -1)
If the calculation would result in a number less than 1, it
shall be an error. Write lines from the edit buffer,
starting at the new value of line, until count lines or the
last line in the edit buffer has been written.
+ The specified line shall be incremented by the following
value:
(((number of '+' characters) -1) x count) +1
If the calculation would result in a number greater than
the last line in the edit buffer, it shall be an error.
Write lines from the edit buffer, starting at the new value
of line, until count lines or the last line in the edit
buffer has been written.
=,. If more than a single '.' or '=' is specified, it shall be
an error. The following steps shall be taken:
1. If count is zero, nothing shall be written.
2. Write as many of the N lines before the current line in
the edit buffer as exist. If count or '!' was
specified, N shall be:
(count -1) /2
Otherwise, N shall be:
(count -3) /2
If N is a number less than 3, no lines shall be
written.
3. If '=' was specified as the type character, write a
line consisting of the smaller of the number of columns
in the display divided by two, or 40 '-' characters.
4. Write the current line.
5. Repeat step 3.
6. Write as many of the N lines after the current line in
the edit buffer as exist. N shall be defined as in
step 2. If N is a number less than 3, no lines shall be
written. If count is less than 3, no lines shall be
written.
^ The specified line shall be decremented by the following
value:
(((number of '^' characters) +1) x count) -1
If the calculation would result in a number less than 1, it
shall be an error. Write lines from the edit buffer,
starting at the new value of line, until count lines or the
last line in the edit buffer has been written.
Current line: Set to the last line written, unless the type is =,
in which case, set to the specified line.
Current column: Set to non-<blank>.
Escape
Synopsis:
! command
[addr]! command
The contents of the line after the '!' shall have '%', '#', and
'!' characters expanded as described in Command Line Parsing in
ex. If the expansion causes the text of the line to change, it
shall be redisplayed, preceded by a single '!' character.
The ex utility shall execute the program named by the shell edit
option. It shall pass two arguments to the program; the first
shall be -c, and the second shall be the expanded arguments to
the ! command as a single argument.
If no lines are specified, the standard input, standard output,
and standard error of the program shall be set to the standard
input, standard output, and standard error of the ex program when
it was invoked. In addition, a warning message shall be written
if the edit buffer has been modified since the last complete
write, and the warn edit option is set.
If lines are specified, they shall be passed to the program as
standard input, and the standard output and standard error of the
program shall replace those lines in the edit buffer. Each line
in the program output (as delimited by <newline> characters or
the end of the output if it is not immediately preceded by a
<newline>), shall be a separate line in the edit buffer. Any
occurrences of <carriage-return> and <newline> pairs in the
output shall be treated as single <newline> characters. The
specified lines shall be copied into the unnamed buffer before
they are replaced, and the unnamed buffer shall become a line-
mode buffer.
If in ex mode, a single '!' character shall be written when the
program completes.
This command shall be affected by the shell and warn edit
options. If no lines are specified, this command shall be
affected by the autowrite and writeany edit options. If lines are
specified, this command shall be affected by the autoprint edit
option.
Current line:
1. If no lines are specified, unchanged.
2. Otherwise, set to the last line read in, if any lines are
read in.
3. Otherwise, set to the line before the first line of the lines
specified, if that line exists.
4. Otherwise, set to the first line of the edit buffer if the
edit buffer is not empty.
5. Otherwise, set to zero.
Current column: If no lines are specified, unchanged. Otherwise,
set to non-<blank>.
Shift Left
Synopsis:
[2addr] <[< ...][count][flags]
Shift the specified lines to the start of the line; the number of
column positions to be shifted shall be the number of command
characters times the value of the shiftwidth edit option. Only
leading <blank> characters shall be deleted or changed into other
<blank> characters in shifting; other characters shall not be
affected.
Lines to be shifted shall be copied into the unnamed buffer,
which shall become a line-mode buffer.
This command shall be affected by the autoprint edit option.
Current line: Set to the last line in the lines specified.
Current column: Set to non-<blank>.
Shift Right
Synopsis:
[2addr] >[> ...][count][flags]
Shift the specified lines away from the start of the line; the
number of column positions to be shifted shall be the number of
command characters times the value of the shiftwidth edit option.
The shift shall be accomplished by adding <blank> characters as a
prefix to the line or changing leading <blank> characters into
other <blank> characters. Empty lines shall not be changed.
Lines to be shifted shall be copied into the unnamed buffer,
which shall become a line-mode buffer.
This command shall be affected by the autoprint edit option.
Current line: Set to the last line in the lines specified.
Current column: Set to non-<blank>.
<control>‐D
Synopsis:
<control>-D
Write the next n lines, where n is the minimum of the values of
the scroll edit option and the number of lines after the current
line in the edit buffer. If the current line is the last line of
the edit buffer it shall be an error.
Current line: Set to the last line written.
Current column: Set to non-<blank>.
Write Line Number
Synopsis:
[1addr] = [flags]
If line is not specified, it shall default to the last line in
the edit buffer. Write the line number of the specified line.
Current line: Unchanged.
Current column: Unchanged.
Execute
Synopsis:
[2addr] @ buffer
[2addr] * buffer
If no buffer is specified or is specified as '@' or '*', the last
buffer executed shall be used. If no previous buffer has been
executed, it shall be an error.
For each line specified by the addresses, set the current line
('.') to the specified line, and execute the contents of the
named buffer (as they were at the time the @ command was
executed) as ex commands. For each line of a line-mode buffer,
and all but the last line of a character-mode buffer, the ex
command parser shall behave as if the line was terminated by a
<newline>.
If an error occurs during this process, or a line specified by
the addresses does not exist when the current line would be set
to it, or more than a single line was specified by the addresses,
and the contents of the edit buffer are replaced (for example, by
the ex :edit command) an error message shall be written, and no
more commands resulting from the execution of this command shall
be processed.
Current line: As specified for the individual ex commands.
Current column: As specified for the individual ex commands.
Regular Expressions in ex
The ex utility shall support regular expressions that are a
superset of the basic regular expressions described in the Base
Definitions volume of POSIX.1‐2017, Section 9.3, Basic Regular
Expressions. A null regular expression ("//") shall be
equivalent to the last regular expression encountered.
Regular expressions can be used in addresses to specify lines
and, in some commands (for example, the substitute command), to
specify portions of a line to be substituted.
The following constructs can be used to enhance the basic regular
expressions:
\< Match the beginning of a word. (See the definition of word
at the beginning of Command Descriptions in ex.)
\> Match the end of a word.
~ Match the replacement part of the last substitute command.
The <tilde> ('~') character can be escaped in a regular
expression to become a normal character with no special
meaning. The <backslash> shall be discarded.
When the editor option magic is not set, the only characters with
special meanings shall be '^' at the beginning of a pattern, '$'
at the end of a pattern, and <backslash>. The characters '.',
'*', '[', and '~' shall be treated as ordinary characters unless
preceded by a <backslash>; when preceded by a <backslash> they
shall regain their special meaning, or in the case of
<backslash>, be handled as a single <backslash>. <backslash>
characters used to escape other characters shall be discarded.
Replacement Strings in ex
The character '&' ('\&' if the editor option magic is not set) in
the replacement string shall stand for the text matched by the
pattern to be replaced. The character '~' ('\~' if magic is not
set) shall be replaced by the replacement part of the previous
substitute command. The sequence '\n', where n is an integer,
shall be replaced by the text matched by the corresponding back-
reference expression. If the corresponding back-reference
expression does not match, then the characters '\n' shall be
replaced by the empty string.
The strings '\l', '\u', '\L', and '\U' can be used to modify the
case of elements in the replacement string (using the '\&' or
"\"digit) notation. The string '\l' ('\u') shall cause the
character that follows to be converted to lowercase (uppercase).
The string '\L' ('\U') shall cause all characters subsequent to
it to be converted to lowercase (uppercase) as they are inserted
by the substitution until the string '\e' or '\E', or the end of
the replacement string, is encountered.
Otherwise, any character following a <backslash> shall be treated
as that literal character, and the escaping <backslash> shall be
discarded.
An example of case conversion with the s command is as follows:
:p
The cat sat on the mat.
:s/\<.at\>/\u&/gp
The Cat Sat on the Mat.
:s/S\(.*\)M/S\U\1\eM/p
The Cat SAT ON THE Mat.
Edit Options in ex
The ex utility has a number of options that modify its behavior.
These options have default settings, which can be changed using
the set command.
Options are Boolean unless otherwise specified.
autoindent, ai
[Default unset]
If autoindent is set, each line in input mode shall be indented
(using first as many <tab> characters as possible, as determined
by the editor option tabstop, and then using <space> characters)
to align with another line, as follows:
1. If in open or visual mode and the text input is part of a
line-oriented command (see the EXTENDED DESCRIPTION in
vi(1p)), align to the first column.
2. Otherwise, if in open or visual mode, indentation for each
line shall be set as follows:
a. If a line was previously inserted as part of this
command, it shall be set to the indentation of the last
inserted line by default, or as otherwise specified for
the <control>‐D character in Input Mode Commands in vi.
b. Otherwise, it shall be set to the indentation of the
previous current line, if any; otherwise, to the first
column.
3. For the ex a, i, and c commands, indentation for each line
shall be set as follows:
a. If a line was previously inserted as part of this
command, it shall be set to the indentation of the last
inserted line by default, or as otherwise specified for
the eof character in Scroll.
b. Otherwise, if the command is the ex a command, it shall
be set to the line appended after, if any; otherwise to
the first column.
c. Otherwise, if the command is the ex i command, it shall
be set to the line inserted before, if any; otherwise to
the first column.
d. Otherwise, if the command is the ex c command, it shall
be set to the indentation of the line replaced.
autoprint, ap
[Default set]
If autoprint is set, the current line shall be written after each
ex command that modifies the contents of the current edit buffer,
and after each tag command for which the tag search pattern was
found or tag line number was valid, unless:
1. The command was executed while in open or visual mode.
2. The command was executed as part of a global or v command or
@ buffer execution.
3. The command was the form of the read command that reads a
file into the edit buffer.
4. The command was the append, change, or insert command.
5. The command was not terminated by a <newline>.
6. The current line shall be written by a flag specified to the
command; for example, delete # shall write the current line
as specified for the flag modifier to the delete command, and
not as specified by the autoprint edit option.
autowrite, aw
[Default unset]
If autowrite is set, and the edit buffer has been modified since
it was last completely written to any file, the contents of the
edit buffer shall be written as if the ex write command had been
specified without arguments, before each command affected by the
autowrite edit option is executed. Appending the character '!'
to the command name of any of the ex commands except '!' shall
prevent the write. If the write fails, it shall be an error and
the command shall not be executed.
beautify, bf
[Default unset]
If beautify is set, all non-printable characters, other than
<tab>, <newline>, and <form-feed> characters, shall be discarded
from text read in from files.
directory, dir
[Default implementation-defined]
The value of this option specifies the directory in which the
editor buffer is to be placed. If this directory is not writable
by the user, the editor shall quit.
edcompatible, ed
[Default unset]
Causes the presence of g and c suffixes on substitute commands to
be remembered, and toggled by repeating the suffixes.
errorbells, eb
[Default unset]
If the editor is in ex mode, and the terminal does not support a
standout mode (such as inverse video), and errorbells is set,
error messages shall be preceded by alerting the terminal.
exrc
[Default unset]
If exrc is set, ex shall access any .exrc file in the current
directory, as described in Initialization in ex and vi. If exrc
is not set, ex shall ignore any .exrc file in the current
directory during initialization, unless the current directory is
that named by the HOME environment variable.
ignorecase, ic
[Default unset]
If ignorecase is set, characters that have uppercase and
lowercase representations shall have those representations
considered as equivalent for purposes of regular expression
comparison.
The ignorecase edit option shall affect all remembered regular
expressions; for example, unsetting the ignorecase edit option
shall cause a subsequent vi n command to search for the last
basic regular expression in a case-sensitive fashion.
list
[Default unset]
If list is set, edit buffer lines written while in ex command
mode shall be written as specified for the print command with the
l flag specified. In open or visual mode, each edit buffer line
shall be displayed as specified for the ex print command with the
l flag specified. In open or visual text input mode, when the
cursor does not rest on any character in the line, it shall rest
on the '$' marking the end of the line.
magic
[Default set]
If magic is set, modify the interpretation of characters in
regular expressions and substitution replacement strings (see
Regular Expressions in ex and Replacement Strings in ex).
mesg
[Default set]
If mesg is set, the permission for others to use the write or
talk commands to write to the terminal shall be turned on while
in open or visual mode. The shell-level command mesg n shall take
precedence over any setting of the ex mesg option; that is, if
mesg y was issued before the editor started (or in a shell
escape), such as:
:!mesg y
the mesg option in ex shall suppress incoming messages, but the
mesg option shall not enable incoming messages if mesg n was
issued.
number, nu
[Default unset]
If number is set, edit buffer lines written while in ex command
mode shall be written with line numbers, in the format specified
by the print command with the # flag specified. In ex text input
mode, each line shall be preceded by the line number it will have
in the file.
In open or visual mode, each edit buffer line shall be displayed
with a preceding line number, in the format specified by the ex
print command with the # flag specified. This line number shall
not be considered part of the line for the purposes of evaluating
the current column; that is, column position 1 shall be the first
column position after the format specified by the print command.
paragraphs, para
[Default in the POSIX locale IPLPPPQPP LIpplpipbp]
The paragraphs edit option shall define additional paragraph
boundaries for the open and visual mode commands. The paragraphs
edit option can be set to a character string consisting of zero
or more character pairs. It shall be an error to set it to an odd
number of characters.
prompt
[Default set]
If prompt is set, ex command mode input shall be prompted for
with a <colon> (':'); when unset, no prompt shall be written.
readonly
[Default see text]
If the readonly edit option is set, read-only mode shall be
enabled (see Write). The readonly edit option shall be
initialized to set if either of the following conditions are
true:
* The command-line option -R was specified.
* Performing actions equivalent to the access() function called
with the following arguments indicates that the file lacks
write permission:
1. The current pathname is used as the path argument.
2. The constant W_OK is used as the amode argument.
The readonly edit option may be initialized to set for other,
implementation-defined reasons. The readonly edit option shall
not be initialized to unset based on any special privileges of
the user or process. The readonly edit option shall be
reinitialized each time that the contents of the edit buffer are
replaced (for example, by an edit or next command) unless the
user has explicitly set it, in which case it shall remain set
until the user explicitly unsets it. Once unset, it shall again
be reinitialized each time that the contents of the edit buffer
are replaced.
redraw
[Default unset]
The editor simulates an intelligent terminal on a dumb terminal.
(Since this is likely to require a large amount of output to the
terminal, it is useful only at high transmission speeds.)
remap
[Default set]
If remap is set, map translation shall allow for maps defined in
terms of other maps; translation shall continue until a final
product is obtained. If unset, only a one-step translation shall
be done.
report
[Default 5]
The value of this report edit option specifies what number of
lines being added, copied, deleted, or modified in the edit
buffer will cause an informational message to be written to the
user. The following conditions shall cause an informational
message. The message shall contain the number of lines added,
copied, deleted, or modified, but is otherwise unspecified.
* An ex or vi editor command, other than open, undo, or visual,
that modifies at least the value of the report edit option
number of lines, and which is not part of an ex global or v
command, or ex or vi buffer execution, shall cause an
informational message to be written.
* An ex yank or vi y or Y command, that copies at least the
value of the report edit option plus 1 number of lines, and
which is not part of an ex global or v command, or ex or vi
buffer execution, shall cause an informational message to be
written.
* An ex global, v, open, undo, or visual command or ex or vi
buffer execution, that adds or deletes a total of at least
the value of the report edit option number of lines, and
which is not part of an ex global or v command, or ex or vi
buffer execution, shall cause an informational message to be
written. (For example, if 3 lines were added and 8 lines
deleted during an ex visual command, 5 would be the number
compared against the report edit option after the command
completed.)
scroll, scr
[Default (number of lines in the display -1)/2]
The value of the scroll edit option shall determine the number of
lines scrolled by the ex <control>‐D and z commands. For the vi
<control>‐D and <control>‐U commands, it shall be the initial
number of lines to scroll when no previous <control>‐D or
<control>‐U command has been executed.
sections
[Default in the POSIX locale NHSHH HUnhsh]
The sections edit option shall define additional section
boundaries for the open and visual mode commands. The sections
edit option can be set to a character string consisting of zero
or more character pairs; it shall be an error to set it to an odd
number of characters.
shell, sh
[Default from the environment variable SHELL]
The value of this option shall be a string. The default shall be
taken from the SHELL environment variable. If the SHELL
environment variable is null or empty, the sh (see sh(1p))
utility shall be the default.
shiftwidth, sw
[Default 8]
The value of this option shall give the width in columns of an
indentation level used during autoindentation and by the shift
commands (< and >).
showmatch, sm
[Default unset]
The functionality described for the showmatch edit option need
not be supported on block-mode terminals or terminals with
insufficient capabilities.
If showmatch is set, in open or visual mode, when a ')' or '}' is
typed, if the matching '(' or '{' is currently visible on the
display, the matching '(' or '{' shall be flagged moving the
cursor to its location for an unspecified amount of time.
showmode
[Default unset]
If showmode is set, in open or visual mode, the current mode that
the editor is in shall be displayed on the last line of the
display. Command mode and text input mode shall be
differentiated; other unspecified modes and implementation-
defined information may be displayed.
slowopen
[Default unset]
If slowopen is set during open and visual text input modes, the
editor shall not update portions of the display other than those
display line columns that display the characters entered by the
user (see Input Mode Commands in vi).
tabstop, ts
[Default 8]
The value of this edit option shall specify the column boundary
used by a <tab> in the display (see autoprint, ap and Input Mode
Commands in vi).
taglength, tl
[Default zero]
The value of this edit option shall specify the maximum number of
characters that are considered significant in the user-specified
tag name and in the tag name from the tags file. If the value is
zero, all characters in both tag names shall be significant.
tags
[Default see text]
The value of this edit option shall be a string of
<blank>-delimited pathnames of files used by the tag command. The
default value is unspecified.
term
[Default from the environment variable TERM]
The value of this edit option shall be a string. The default
shall be taken from the TERM variable in the environment. If the
TERM environment variable is empty or null, the default is
unspecified. The editor shall use the value of this edit option
to determine the type of the display device.
The results are unspecified if the user changes the value of the
term edit option after editor initialization.
terse
[Default unset]
If terse is set, error messages may be less verbose. However,
except for this caveat, error messages are unspecified.
Furthermore, not all error messages need change for different
settings of this option.
warn
[Default set]
If warn is set, and the contents of the edit buffer have been
modified since they were last completely written, the editor
shall write a warning message before certain ! commands (see
Escape).
window
[Default see text]
A value used in open and visual mode, by the <control>‐B and
<control>‐F commands, and, in visual mode, to specify the number
of lines displayed when the screen is repainted.
If the -w command-line option is not specified, the default value
shall be set to the value of the LINES environment variable. If
the LINES environment variable is empty or null, the default
shall be the number of lines in the display minus 1.
Setting the window edit option to zero or to a value greater than
the number of lines in the display minus 1 (either explicitly or
based on the -w option or the LINES environment variable) shall
cause the window edit option to be set to the number of lines in
the display minus 1.
The baud rate of the terminal line may change the default in an
implementation-defined manner.
wrapmargin, wm
[Default 0]
If the value of this edit option is zero, it shall have no
effect.
If not in the POSIX locale, the effect of this edit option is
implementation-defined.
Otherwise, it shall specify a number of columns from the ending
margin of the terminal.
During open and visual text input modes, for each character for
which any part of the character is displayed in a column that is
less than wrapmargin columns from the ending margin of the
display line, the editor shall behave as follows:
1. If the character triggering this event is a <blank>, it, and
all immediately preceding <blank> characters on the current
line entered during the execution of the current text input
command, shall be discarded, and the editor shall behave as
if the user had entered a single <newline> instead. In
addition, if the next user-entered character is a <space>, it
shall be discarded as well.
2. Otherwise, if there are one or more <blank> characters on the
current line immediately preceding the last group of inserted
non-<blank> characters which was entered during the execution
of the current text input command, the <blank> characters
shall be replaced as if the user had entered a single
<newline> instead.
If the autoindent edit option is set, and the events described in
1. or 2. are performed, any <blank> characters at or after the
cursor in the current line shall be discarded.
The ending margin shall be determined by the system or overridden
by the user, as described for COLUMNS in the ENVIRONMENT
VARIABLES section and the Base Definitions volume of
POSIX.1‐2017, Chapter 8, Environment Variables.
wrapscan, ws
[Default set]
If wrapscan is set, searches (the ex / or ? addresses, or open
and visual mode /, ?, N, and n commands) shall wrap around the
beginning or end of the edit buffer; when unset, searches shall
stop at the beginning or end of the edit buffer.
writeany, wa
[Default unset]
If writeany is set, some of the checks performed when executing
the ex write commands shall be inhibited, as described in editor
option autowrite.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
When any error is encountered and the standard input is not a
terminal device file, ex shall not write the file or return to
command or text input mode, and shall terminate with a non-zero
exit status.
Otherwise, when an unrecoverable error is encountered, it shall
be equivalent to a SIGHUP asynchronous event.
Otherwise, when an error is encountered, the editor shall behave
as specified in Command Line Parsing in ex.
The following sections are informative.
If a SIGSEGV signal is received while ex is saving a file, the
file might not be successfully saved.
The next command can accept more than one file, so usage such as:
next `ls [abc]*`
is valid; it would not be valid for the edit or read commands,
for example, because they expect only one file and unspecified
results occur.
None.
The ex/vi specification is based on the historical practice found
in the 4 BSD and System V implementations of ex and vi.
A restricted editor (both the historical red utility and
modifications to ex) were considered and rejected for inclusion.
Neither option provided the level of security that users might
expect.
It is recognized that ex visual mode and related features would
be difficult, if not impossible, to implement satisfactorily on a
block-mode terminal, or a terminal without any form of cursor
addressing; thus, it is not a mandatory requirement that such
features should work on all terminals. It is the intention,
however, that an ex implementation should provide the full set of
capabilities on all terminals capable of supporting them.
Options
The -c replacement for +command was inspired by the -e option of
sed. Historically, all such commands (see edit and next as well)
were executed from the last line of the edit buffer. This meant,
for example, that "+/pattern" would fail unless the wrapscan
option was set. POSIX.1‐2008 requires conformance to historical
practice. The +command option is no longer specified by
POSIX.1‐2008 but may be present in some implementations.
Historically, some implementations restricted the ex commands
that could be listed as part of the command line arguments. For
consistency, POSIX.1‐2008 does not permit these restrictions.
In historical implementations of the editor, the -R option (and
the readonly edit option) only prevented overwriting of files;
appending to files was still permitted, mapping loosely into the
csh noclobber variable. Some implementations, however, have not
followed this semantic, and readonly does not permit appending
either. POSIX.1‐2008 follows the latter practice, believing that
it is a more obvious and intuitive meaning of readonly.
The -s option suppresses all interactive user feedback and is
useful for editing scripts in batch jobs. The list of specific
effects is historical practice. The terminal type ``incapable of
supporting open and visual modes'' has historically been named
``dumb''.
The -t option was required because the ctags utility appears in
POSIX.1‐2008 and the option is available in all historical
implementations of ex.
Historically, the ex and vi utilities accepted a -x option, which
did encryption based on the algorithm found in the historical
crypt utility. The -x option for encryption, and the associated
crypt utility, were omitted because the algorithm used was not
specifiable and the export control laws of some nations make it
difficult to export cryptographic technology. In addition, it did
not historically provide the level of security that users might
expect.
Standard Input
An end-of-file condition is not equivalent to an end-of-file
character. A common end-of-file character, <control>‐D, is
historically an ex command.
There was no maximum line length in historical implementations of
ex. Specifically, as it was parsed in chunks, the addresses had
a different maximum length than the filenames. Further, the
maximum line buffer size was declared as BUFSIZ, which was
different lengths on different systems. This version selected the
value of {LINE_MAX} to impose a reasonable restriction on
portable usage of ex and to aid test suite writers in their
development of realistic tests that exercise this limit.
Input Files
It was an explicit decision by the standard developers that a
<newline> be added to any file lacking one. It was believed that
this feature of ex and vi was relied on by users in order to make
text files lacking a trailing <newline> more portable. It is
recognized that this will require a user-specified option or
extension for implementations that permit ex and vi to edit files
of type other than text if such files are not otherwise
identified by the system. It was agreed that the ability to edit
files of arbitrary type can be useful, but it was not considered
necessary to mandate that an ex or vi implementation be required
to handle files other than text files.
The paragraph in the INPUT FILES section, ``By default, ...'', is
intended to close a long-standing security problem in ex and vi;
that of the ``modeline'' or ``modelines'' edit option. This
feature allows any line in the first or last five lines of the
file containing the strings "ex:" or "vi:" (and, apparently,
"ei:" or "vx:") to be a line containing editor commands, and ex
interprets all the text up to the next ':' or <newline> as a
command. Consider the consequences, for example, of an
unsuspecting user using ex or vi as the editor when replying to a
mail message in which a line such as:
ex:! rm -rf :
appeared in the signature lines. The standard developers believed
strongly that an editor should not by default interpret any lines
of a file. Vendors are strongly urged to delete this feature from
their implementations of ex and vi.
Asynchronous Events
The intention of the phrase ``complete write'' is that the entire
edit buffer be written to stable storage. The note regarding
temporary files is intended for implementations that use
temporary files to back edit buffers unnamed by the user.
Historically, SIGQUIT was ignored by ex, but was the equivalent
of the Q command in visual mode; that is, it exited visual mode
and entered ex mode. POSIX.1‐2008 permits, but does not require,
this behavior. Historically, SIGINT was often used by vi users to
terminate text input mode (<control>‐C is often easier to enter
than <ESC>). Some implementations of vi alerted the terminal on
this event, and some did not. POSIX.1‐2008 requires that SIGINT
behave identically to <ESC>, and that the terminal not be
alerted.
Historically, suspending the ex editor during text input mode was
similar to SIGINT, as completed lines were retained, but any
partial line discarded, and the editor returned to command mode.
POSIX.1‐2008 is silent on this issue; implementations are
encouraged to follow historical practice, where possible.
Historically, the vi editor did not treat SIGTSTP as an
asynchronous event, and it was therefore impossible to suspend
the editor in visual text input mode. There are two major
reasons for this. The first is that SIGTSTP is a broadcast signal
on UNIX systems, and the chain of events where the shell execs an
application that then execs vi usually caused confusion for the
terminal state if SIGTSTP was delivered to the process group in
the default manner. The second was that most implementations of
the UNIX curses package did not handle SIGTSTP safely, and the
receipt of SIGTSTP at the wrong time would cause them to crash.
POSIX.1‐2008 is silent on this issue; implementations are
encouraged to treat suspension as an asynchronous event if
possible.
Historically, modifications to the edit buffer made before SIGINT
interrupted an operation were retained; that is, anywhere from
zero to all of the lines to be modified might have been modified
by the time the SIGINT arrived. These changes were not discarded
by the arrival of SIGINT. POSIX.1‐2008 permits this behavior,
noting that the undo command is required to be able to undo these
partially completed commands.
The action taken for signals other than SIGINT, SIGCONT, SIGHUP,
and SIGTERM is unspecified because some implementations attempt
to save the edit buffer in a useful state when other signals are
received.
Standard Error
For ex/vi, diagnostic messages are those messages reported as a
result of a failed attempt to invoke ex or vi, such as invalid
options or insufficient resources, or an abnormal termination
condition. Diagnostic messages should not be confused with the
error messages generated by inappropriate or illegal user
commands.
Initialization in ex and vi
If an ex command (other than cd, chdir, or source) has a filename
argument, one or both of the alternate and current pathnames will
be set. Informally, they are set as follows:
1. If the ex command is one that replaces the contents of the
edit buffer, and it succeeds, the current pathname will be
set to the filename argument (the first filename argument in
the case of the next command) and the alternate pathname will
be set to the previous current pathname, if there was one.
2. In the case of the file read/write forms of the read and
write commands, if there is no current pathname, the current
pathname will be set to the filename argument.
3. Otherwise, the alternate pathname will be set to the filename
argument.
For example, :edit foo and :recover foo, when successful, set the
current pathname, and, if there was a previous current pathname,
the alternate pathname. The commands :write, !command, and :edit
set neither the current or alternate pathnames. If the :edit foo
command were to fail for some reason, the alternate pathname
would be set. The read and write commands set the alternate
pathname to their file argument, unless the current pathname is
not set, in which case they set the current pathname to their
file arguments. The alternate pathname was not historically set
by the :source command. POSIX.1‐2008 requires conformance to
historical practice. Implementations adding commands that take
filenames as arguments are encouraged to set the alternate
pathname as described here.
Historically, ex and vi read the .exrc file in the $HOME
directory twice, if the editor was executed in the $HOME
directory. POSIX.1‐2008 prohibits this behavior.
Historically, the 4 BSD ex and vi read the $HOME and local .exrc
files if they were owned by the real ID of the user, or the
sourceany option was set, regardless of other considerations.
This was a security problem because it is possible to put normal
UNIX system commands inside a .exrc file. POSIX.1‐2008 does not
specify the sourceany option, and historical implementations are
encouraged to delete it.
The .exrc files must be owned by the real ID of the user, and not
writable by anyone other than the owner. The appropriate
privileges exception is intended to permit users to acquire
special privileges, but continue to use the .exrc files in their
home directories.
System V Release 3.2 and later vi implementations added the
option [no]exrc. The behavior is that local .exrc files are
read-only if the exrc option is set. The default for the exrc
option was off, so by default, local .exrc files were not read.
The problem this was intended to solve was that System V
permitted users to give away files, so there is no possible
ownership or writeability test to ensure that the file is safe.
This is still a security problem on systems where users can give
away files, but there is nothing additional that POSIX.1‐2008 can
do. The implementation-defined exception is intended to permit
groups to have local .exrc files that are shared by users, by
creating pseudo-users to own the shared files.
POSIX.1‐2008 does not mention system-wide ex and vi start-up
files. While they exist in several implementations of ex and vi,
they are not present in any implementations considered historical
practice by POSIX.1‐2008. Implementations that have such files
should use them only if they are owned by the real user ID or an
appropriate user (for example, root on UNIX systems) and if they
are not writable by any user other than their owner. System-wide
start-up files should be read before the EXINIT variable,
$HOME/.exrc, or local .exrc files are evaluated.
Historically, any ex command could be entered in the EXINIT
variable or the .exrc file, although ones requiring that the edit
buffer already contain lines of text generally caused historical
implementations of the editor to drop core. POSIX.1‐2008
requires that any ex command be permitted in the EXINIT variable
and .exrc files, for simplicity of specification and consistency,
although many of them will obviously fail under many
circumstances.
The initialization of the contents of the edit buffer uses the
phrase ``the effect shall be'' with regard to various ex
commands. The intent of this phrase is that edit buffer contents
loaded during the initialization phase not be lost; that is,
loading the edit buffer should fail if the .exrc file read in the
contents of a file and did not subsequently write the edit
buffer. An additional intent of this phrase is to specify that
the initial current line and column is set as specified for the
individual ex commands.
Historically, the -t option behaved as if the tag search were a
+command; that is, it was executed from the last line of the file
specified by the tag. This resulted in the search failing if the
pattern was a forward search pattern and the wrapscan edit option
was not set. POSIX.1‐2008 does not permit this behavior,
requiring that the search for the tag pattern be performed on the
entire file, and, if not found, that the current line be set to a
more reasonable location in the file.
Historically, the empty edit buffer presented for editing when a
file was not specified by the user was unnamed. This is permitted
by POSIX.1‐2008; however, implementations are encouraged to
provide users a temporary filename for this buffer because it
permits them the use of ex commands that use the current pathname
during temporary edit sessions.
Historically, the file specified using the -t option was not part
of the current argument list. This practice is permitted by
POSIX.1‐2008; however, implementations are encouraged to include
its name in the current argument list for consistency.
Historically, the -c command was generally not executed until a
file that already exists was edited. POSIX.1‐2008 requires
conformance to this historical practice. Commands that could
cause the -c command to be executed include the ex commands edit,
next, recover, rewind, and tag, and the vi commands <control>‐^
and <control>‐]. Historically, reading a file into an edit
buffer did not cause the -c command to be executed (even though
it might set the current pathname) with the exception that it did
cause the -c command to be executed if: the editor was in ex
mode, the edit buffer had no current pathname, the edit buffer
was empty, and no read commands had yet been attempted. For
consistency and simplicity of specification, POSIX.1‐2008 does
not permit this behavior.
Historically, the -r option was the same as a normal edit session
if there was no recovery information available for the file. This
allowed users to enter:
vi -r *.c
and recover whatever files were recoverable. In some
implementations, recovery was attempted only on the first file
named, and the file was not entered into the argument list; in
others, recovery was attempted for each file named. In addition,
some historical implementations ignored -r if -t was specified or
did not support command line file arguments with the -t option.
For consistency and simplicity of specification, POSIX.1‐2008
disallows these special cases, and requires that recovery be
attempted the first time each file is edited.
Historically, vi initialized the ` and ' marks, but ex did not.
This meant that if the first command in ex mode was visual or if
an ex command was executed first (for example, vi +10 file), vi
was entered without the marks being initialized. Because the
standard developers believed the marks to be generally useful,
and for consistency and simplicity of specification, POSIX.1‐2008
requires that they always be initialized if in open or visual
mode, or if in ex mode and the edit buffer is not empty. Not
initializing it in ex mode if the edit buffer is empty is
historical practice; however, it has always been possible to set
(and use) marks in empty edit buffers in open and visual mode
edit sessions.
Addressing
Historically, ex and vi accepted the additional addressing forms
'\/' and '\?'. They were equivalent to "//" and "??",
respectively. They are not required by POSIX.1‐2008, mostly
because nobody can remember whether they ever did anything
different historically.
Historically, ex and vi permitted an address of zero for several
commands, and permitted the % address in empty files for others.
For consistency, POSIX.1‐2008 requires support for the former in
the few commands where it makes sense, and disallows it
otherwise. In addition, because POSIX.1‐2008 requires that % be
logically equivalent to "1,$", it is also supported where it
makes sense and disallowed otherwise.
Historically, the % address could not be followed by further
addresses. For consistency and simplicity of specification,
POSIX.1‐2008 requires that additional addresses be supported.
All of the following are valid addresses:
+++ Three lines after the current line.
/re/- One line before the next occurrence of re.
-2 Two lines before the current line.
3 ---- 2 Line one (note intermediate negative address).
1 2 3 Line six.
Any number of addresses can be provided to commands taking
addresses; for example, "1,2,3,4,5p" prints lines 4 and 5,
because two is the greatest valid number of addresses accepted by
the print command. This, in combination with the <semicolon>
delimiter, permits users to create commands based on ordered
patterns in the file. For example, the command 3;/foo/;+2print
will display the first line after line 3 that contains the
pattern foo, plus the next two lines. Note that the address 3;
must be evaluated before being discarded because the search
origin for the /foo/ command depends on this.
Historically, values could be added to addresses by including
them after one or more <blank> characters; for example, 3 - 5p
wrote the seventh line of the file, and /foo/ 5 was the same as
/foo/+5. However, only absolute values could be added; for
example, 5 /foo/ was an error. POSIX.1‐2008 requires conformance
to historical practice. Address offsets are separately specified
from addresses because they could historically be provided to
visual mode search commands.
Historically, any missing addresses defaulted to the current
line. This was true for leading and trailing <comma>-delimited
addresses, and for trailing <semicolon>-delimited addresses. For
consistency, POSIX.1‐2008 requires it for leading <semicolon>
addresses as well.
Historically, ex and vi accepted the '^' character as both an
address and as a flag offset for commands. In both cases it was
identical to the '-' character. POSIX.1‐2008 does not require or
prohibit this behavior.
Historically, the enhancements to basic regular expressions could
be used in addressing; for example, '~', '\<', and '\>'.
POSIX.1‐2008 requires conformance to historical practice; that
is, that regular expression usage be consistent, and that regular
expression enhancements be supported wherever regular expressions
are used.
Command Line Parsing in ex
Historical ex command parsing was even more complex than that
described here. POSIX.1‐2008 requires the subset of the command
parsing that the standard developers believed was documented and
that users could reasonably be expected to use in a portable
fashion, and that was historically consistent between
implementations. (The discarded functionality is obscure, at
best.) Historical implementations will require changes in order
to comply with POSIX.1‐2008; however, users are not expected to
notice any of these changes. Most of the complexity in ex
parsing is to handle three special termination cases:
1. The !, global, v, and the filter versions of the read and
write commands are delimited by <newline> characters (they
can contain <vertical-line> characters that are usually shell
pipes).
2. The ex, edit, next, and visual in open and visual mode
commands all take ex commands, optionally containing
<vertical-line> characters, as their first arguments.
3. The s command takes a regular expression as its first
argument, and uses the delimiting characters to delimit the
command.
Historically, <vertical-line> characters in the +command argument
of the ex, edit, next, vi, and visual commands, and in the
pattern and replacement parts of the s command, did not delimit
the command, and in the filter cases for read and write, and the
!, global, and v commands, they did not delimit the command at
all. For example, the following commands are all valid:
:edit +25 | s/abc/ABC/ file.c
:s/ | /PIPE/
:read !spell % | columnate
:global/pattern/p | l
:s/a/b/ | s/c/d | set
Historically, empty or <blank> filled lines in .exrc files and
sourced files (as well as EXINIT variables and ex command
scripts) were treated as default commands; that is, print
commands. POSIX.1‐2008 specifically requires that they be ignored
when encountered in .exrc and sourced files to eliminate a common
source of new user error.
Historically, ex commands with multiple adjacent (or
<blank>-separated) vertical lines were handled oddly when
executed from ex mode. For example, the command ||| <carriage-
return>, when the cursor was on line 1, displayed lines 2, 3, and
5 of the file. In addition, the command | would only display the
line after the next line, instead of the next two lines. The
former worked more logically when executed from vi mode, and
displayed lines 2, 3, and 4. POSIX.1‐2008 requires the vi
behavior; that is, a single default command and line number
increment for each command separator, and trailing <newline>
characters after <vertical-line> separators are discarded.
Historically, ex permitted a single extra <colon> as a leading
command character; for example, :g/pattern/:p was a valid
command. POSIX.1‐2008 generalizes this to require that any number
of leading <colon> characters be stripped.
Historically, any prefix of the delete command could be followed
without intervening <blank> characters by a flag character
because in the command d p, p is interpreted as the buffer p.
POSIX.1‐2008 requires conformance to historical practice.
Historically, the k command could be followed by the mark name
without intervening <blank> characters. POSIX.1‐2008 requires
conformance to historical practice.
Historically, the s command could be immediately followed by flag
and option characters; for example, s/e/E/|s|sgc3p was a valid
command. However, flag characters could not stand alone; for
example, the commands sp and s l would fail, while the command
sgp and s gl would succeed. (Obviously, the '#' flag character
was used as a delimiter character if it followed the command.)
Another issue was that option characters had to precede flag
characters even when the command was fully specified; for
example, the command s/e/E/pg would fail, while the command
s/e/E/gp would succeed. POSIX.1‐2008 requires conformance to
historical practice.
Historically, the first command name that had a prefix matching
the input from the user was the executed command; for example,
ve, ver, and vers all executed the version command. Commands were
in a specific order, however, so that a matched append, not
abbreviate. POSIX.1‐2008 requires conformance to historical
practice. The restriction on command search order for
implementations with extensions is to avoid the addition of
commands such that the historical prefixes would fail to work
portably.
Historical implementations of ex and vi did not correctly handle
multiple ex commands, separated by <vertical-line> characters,
that entered or exited visual mode or the editor. Because
implementations of vi exist that do not exhibit this failure
mode, POSIX.1‐2008 does not permit it.
The requirement that alphabetic command names consist of all
following alphabetic characters up to the next non-alphabetic
character means that alphabetic command names must be separated
from their arguments by one or more non-alphabetic characters,
normally a <blank> or '!' character, except as specified for the
exceptions, the delete, k, and s commands.
Historically, the repeated execution of the ex default print
commands (<control>‐D, eof, <newline>, <carriage-return>) erased
any prompting character and displayed the next lines without
scrolling the terminal; that is, immediately below any previously
displayed lines. This provided a cleaner presentation of the
lines in the file for the user. POSIX.1‐2008 does not require
this behavior because it may be impossible in some situations;
however, implementations are strongly encouraged to provide this
semantic if possible.
Historically, it was possible to change files in the middle of a
command, and have the rest of the command executed in the new
file; for example:
:edit +25 file.c | s/abc/ABC/ | 1
was a valid command, and the substitution was attempted in the
newly edited file. POSIX.1‐2008 requires conformance to
historical practice. The following commands are examples that
exercise the ex parser:
echo 'foo | bar' > file1; echo 'foo/bar' > file2;
vi
:edit +1 | s/|/PIPE/ | w file1 | e file2 | 1 | s/\//SLASH/ | wq
Historically, there was no protection in editor implementations
to avoid ex global, v, @, or * commands changing edit buffers
during execution of their associated commands. Because this would
almost invariably result in catastrophic failure of the editor,
and implementations exist that do exhibit these problems,
POSIX.1‐2008 requires that changing the edit buffer during a
global or v command, or during a @ or * command for which there
will be more than a single execution, be an error.
Implementations supporting multiple edit buffers simultaneously
are strongly encouraged to apply the same semantics to switching
between buffers as well.
The ex command quoting required by POSIX.1‐2008 is a superset of
the quoting in historical implementations of the editor. For
example, it was not historically possible to escape a <blank> in
a filename; for example, :edit foo\\\ bar would report that too
many filenames had been entered for the edit command, and there
was no method of escaping a <blank> in the first argument of an
edit, ex, next, or visual command at all. POSIX.1‐2008 extends
historical practice, requiring that quoting behavior be made
consistent across all ex commands, except for the map, unmap,
abbreviate, and unabbreviate commands, which historically used
<control>‐V instead of <backslash> characters for quoting. For
those four commands, POSIX.1‐2008 requires conformance to
historical practice.
Backslash quoting in ex is non-intuitive. <backslash>-escapes
are ignored unless they escape a special character; for example,
when performing file argument expansion, the string "\\%" is
equivalent to '\%', not "\<current pathname>". This can be
confusing for users because <backslash> is usually one of the
characters that causes shell expansion to be performed, and
therefore shell quoting rules must be taken into consideration.
Generally, quoting characters are only considered if they escape
a special character, and a quoting character must be provided for
each layer of parsing for which the character is special. As
another example, only a single <backslash> is necessary for the
'\l' sequence in substitute replacement patterns, because the
character 'l' is not special to any parsing layer above it.
<control>‐V quoting in ex is slightly different from backslash
quoting. In the four commands where <control>‐V quoting applies
(abbreviate, unabbreviate, map, and unmap), any character may be
escaped by a <control>‐V whether it would have a special meaning
or not. POSIX.1‐2008 requires conformance to historical practice.
Historical implementations of the editor did not require
delimiters within character classes to be escaped; for example,
the command :s/[/]// on the string "xxx/yyy" would delete the '/'
from the string. POSIX.1‐2008 disallows this historical practice
for consistency and because it places a large burden on
implementations by requiring that knowledge of regular
expressions be built into the editor parser.
Historically, quoting <newline> characters in ex commands was
handled inconsistently. In most cases, the <newline> character
always terminated the command, regardless of any preceding escape
character, because <backslash> characters did not escape
<newline> characters for most ex commands. However, some ex
commands (for example, s, map, and abbreviation) permitted
<newline> characters to be escaped (although in the case of map
and abbreviation, <control>‐V characters escaped them instead of
<backslash> characters). This was true in not only the command
line, but also .exrc and sourced files. For example, the command:
map = foo<control-V><newline>bar
would succeed, although it was sometimes difficult to get the
<control>‐V and the inserted <newline> passed to the ex parser.
For consistency and simplicity of specification, POSIX.1‐2008
requires that it be possible to escape <newline> characters in ex
commands at all times, using <backslash> characters for most ex
commands, and using <control>‐V characters for the map and
abbreviation commands. For example, the command
print<newline>list is required to be parsed as the single command
print<newline>list. While this differs from historical practice,
POSIX.1‐2008 developers believed it unlikely that any script or
user depended on the historical behavior.
Historically, an error in a command specified using the -c option
did not cause the rest of the -c commands to be discarded.
POSIX.1‐2008 disallows this for consistency with mapped keys, the
@, global, source, and v commands, the EXINIT environment
variable, and the .exrc files.
Input Editing in ex
One of the common uses of the historical ex editor is over slow
network connections. Editors that run in canonical mode can
require far less traffic to and from, and far less processing on,
the host machine, as well as more easily supporting block-mode
terminals. For these reasons, POSIX.1‐2008 requires that ex be
implemented using canonical mode input processing, as was done
historically.
POSIX.1‐2008 does not require the historical 4 BSD input editing
characters ``word erase'' or ``literal next''. For this reason,
it is unspecified how they are handled by ex, although they must
have the required effect. Implementations that resolve them after
the line has been ended using a <newline> or <control>‐M
character, and implementations that rely on the underlying system
terminal support for this processing, are both conforming.
Implementations are strongly urged to use the underlying system
functionality, if at all possible, for compatibility with other
system text input interfaces.
Historically, when the eof character was used to decrement the
autoindent level, the cursor moved to display the new end of the
autoindent characters, but did not move the cursor to a new line,
nor did it erase the <control>‐D character from the line.
POSIX.1‐2008 does not specify that the cursor remain on the same
line or that the rest of the line is erased; however,
implementations are strongly encouraged to provide the best
possible user interface; that is, the cursor should remain on the
same line, and any <control>‐D character on the line should be
erased.
POSIX.1‐2008 does not require the historical 4 BSD input editing
character ``reprint'', traditionally <control>‐R, which
redisplayed the current input from the user. For this reason, and
because the functionality cannot be implemented after the line
has been terminated by the user, POSIX.1‐2008 makes no
requirements about this functionality. Implementations are
strongly urged to make this historical functionality available,
if possible.
Historically, <control>‐Q did not perform a literal next function
in ex, as it did in vi. POSIX.1‐2008 requires conformance to
historical practice to avoid breaking historical ex scripts and
.exrc files.
eof
Whether the eof character immediately modifies the autoindent
characters in the prompt is left unspecified so that
implementations can conform in the presence of systems that do
not support this functionality. Implementations are encouraged to
modify the line and redisplay it immediately, if possible.
The specification of the handling of the eof character differs
from historical practice only in that eof characters are not
discarded if they follow normal characters in the text input.
Historically, they were always discarded.
Command Descriptions in ex
Historically, several commands (for example, global, v, visual,
s, write, wq, yank, !, <, >, &, and ~) were executable in empty
files (that is, the default address(es) were 0), or permitted
explicit addresses of 0 (for example, 0 was a valid address, or
0,0 was a valid range). Addresses of 0, or command execution in
an empty file, make sense only for commands that add new text to
the edit buffer or write commands (because users may wish to
write empty files). POSIX.1‐2008 requires this behavior for such
commands and disallows it otherwise, for consistency and
simplicity of specification.
A count to an ex command has been historically corrected to be no
greater than the last line in a file; for example, in a five-line
file, the command 1,6print would fail, but the command 1print300
would succeed. POSIX.1‐2008 requires conformance to historical
practice.
Historically, the use of flags in ex commands could be obscure.
General historical practice was as described by POSIX.1‐2008, but
there were some special cases. For instance, the list, number,
and print commands ignored trailing address offsets; for example,
3p +++# would display line 3, and 3 would be the current line
after the execution of the command. The open and visual commands
ignored both the trailing offsets and the trailing flags. Also,
flags specified to the open and visual commands interacted badly
with the list edit option, and setting and then unsetting it
during the open/visual session would cause vi to stop displaying
lines in the specified format. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit any of these
exceptions to the general rule.
POSIX.1‐2008 uses the word copy in several places when discussing
buffers. This is not intended to imply implementation.
Historically, ex users could not specify numeric buffers because
of the ambiguity this would cause; for example, in the command
3 delete 2, it is unclear whether 2 is a buffer name or a count.
POSIX.1‐2008 requires conformance to historical practice by
default, but does not preclude extensions.
Historically, the contents of the unnamed buffer were frequently
discarded after commands that did not explicitly affect it; for
example, when using the edit command to switch files. For
consistency and simplicity of specification, POSIX.1‐2008 does
not permit this behavior.
The ex utility did not historically have access to the numeric
buffers, and, furthermore, deleting lines in ex did not modify
their contents. For example, if, after doing a delete in vi, the
user switched to ex, did another delete, and then switched back
to vi, the contents of the numeric buffers would not have
changed. POSIX.1‐2008 requires conformance to historical
practice. Numeric buffers are described in the ex utility in
order to confine the description of buffers to a single location
in POSIX.1‐2008.
The metacharacters that trigger shell expansion in file arguments
match historical practice, as does the method for doing shell
expansion. Implementations wishing to provide users with the
flexibility to alter the set of metacharacters are encouraged to
provide a shellmeta string edit option.
Historically, ex commands executed from vi refreshed the screen
when it did not strictly need to do so; for example,
:!date > /dev/null does not require a screen refresh because the
output of the UNIX date command requires only a single line of
the screen. POSIX.1‐2008 requires that the screen be refreshed if
it has been overwritten, but makes no requirements as to how an
implementation should make that determination. Implementations
may prompt and refresh the screen regardless.
Abbreviate
Historical practice was that characters that were entered as part
of an abbreviation replacement were subject to map expansions,
the showmatch edit option, further abbreviation expansions, and
so on; that is, they were logically pushed onto the terminal
input queue, and were not a simple replacement. POSIX.1‐2008
requires conformance to historical practice. Historical practice
was that whenever a non-word character (that had not been escaped
by a <control>‐V) was entered after a word character, vi would
check for abbreviations. The check was based on the type of the
character entered before the word character of the word/non-word
pair that triggered the check. The word character of the
word/non-word pair that triggered the check and all characters
entered before the trigger pair that were of that type were
included in the check, with the exception of <blank> characters,
which always delimited the abbreviation.
This means that, for the abbreviation to work, the lhs must end
with a word character, there can be no transitions from word to
non-word characters (or vice versa) other than between the last
and next-to-last characters in the lhs, and there can be no
<blank> characters in the lhs. In addition, because of the
historical quoting rules, it was impossible to enter a literal
<control>‐V in the lhs. POSIX.1‐2008 requires conformance to
historical practice. Historical implementations did not inform
users when abbreviations that could never be used were entered;
implementations are strongly encouraged to do so.
For example, the following abbreviations will work:
:ab (p REPLACE
:ab p REPLACE
:ab ((p REPLACE
The following abbreviations will not work:
:ab ( REPLACE
:ab (pp REPLACE
Historical practice is that words on the vi colon command line
were subject to abbreviation expansion, including the arguments
to the abbrev (and more interestingly) the unabbrev command.
Because there are implementations that do not do abbreviation
expansion for the first argument to those commands, this is
permitted, but not required, by POSIX.1‐2008. However, the
following sequence:
:ab foo bar
:ab foo baz
resulted in the addition of an abbreviation of "baz" for the
string "bar" in historical ex/vi, and the sequence:
:ab foo1 bar
:ab foo2 bar
:unabbreviate foo2
deleted the abbreviation "foo1", not "foo2". These behaviors are
not permitted by POSIX.1‐2008 because they clearly violate the
expectations of the user.
It was historical practice that <control>‐V, not <backslash>,
characters be interpreted as escaping subsequent characters in
the abbreviate command. POSIX.1‐2008 requires conformance to
historical practice; however, it should be noted that an
abbreviation containing a <blank> will never work.
Append
Historically, any text following a <vertical-line> command
separator after an append, change, or insert command became part
of the insert text. For example, in the command:
:g/pattern/append|stuff1
a line containing the text "stuff1" would be appended to each
line matching pattern. It was also historically valid to enter:
:append|stuff1
stuff2
.
and the text on the ex command line would be appended along with
the text inserted after it. There was an historical bug,
however, that the user had to enter two terminating lines (the
'.' lines) to terminate text input mode in this case.
POSIX.1‐2008 requires conformance to historical practice, but
disallows the historical need for multiple terminating lines.
Change
See the RATIONALE for the append command. Historical practice for
cursor positioning after the change command when no text is
input, is as described in POSIX.1‐2008. However, one System V
implementation is known to have been modified such that the
cursor is positioned on the first address specified, and not on
the line before the first address. POSIX.1‐2008 disallows this
modification for consistency.
Historically, the change command did not support buffer
arguments, although some implementations allow the specification
of an optional buffer. This behavior is neither required nor
disallowed by POSIX.1‐2008.
Change Directory
A common extension in ex implementations is to use the elements
of a cdpath edit option as prefix directories for path arguments
to chdir that are relative pathnames and that do not have '.' or
".." as their first component. Elements in the cdpath edit option
are <colon>-separated. The initial value of the cdpath edit
option is the value of the shell CDPATH environment variable.
This feature was not included in POSIX.1‐2008 because it does not
exist in any of the implementations considered historical
practice.
Copy
Historical implementations of ex permitted copies to lines inside
of the specified range; for example, :2,5copy3 was a valid
command. POSIX.1‐2008 requires conformance to historical
practice.
Delete
POSIX.1‐2008 requires support for the historical parsing of a
delete command followed by flags, without any intervening <blank>
characters. For example:
1dp Deletes the first line and prints the line that was
second.
1delep As for 1dp.
1d Deletes the first line, saving it in buffer p.
1d p1l (Pee-one-ell.) Deletes the first line, saving it in
buffer p, and listing the line that was second.
Edit
Historically, any ex command could be entered as a +command
argument to the edit command, although some (for example, insert
and append) were known to confuse historical implementations. For
consistency and simplicity of specification, POSIX.1‐2008
requires that any command be supported as an argument to the edit
command.
Historically, the command argument was executed with the current
line set to the last line of the file, regardless of whether the
edit command was executed from visual mode or not. POSIX.1‐2008
requires conformance to historical practice.
Historically, the +command specified to the edit and next
commands was delimited by the first <blank>, and there was no way
to quote them. For consistency, POSIX.1‐2008 requires that the
usual ex backslash quoting be provided.
Historically, specifying the +command argument to the edit
command required a filename to be specified as well; for example,
:edit +100 would always fail. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this usage to fail
for that reason.
Historically, only the cursor position of the last file edited
was remembered by the editor. POSIX.1‐2008 requires that this be
supported; however, implementations are permitted to remember and
restore the cursor position for any file previously edited.
File
Historical versions of the ex editor file command displayed a
current line and number of lines in the edit buffer of 0 when the
file was empty, while the vi <control>‐G command displayed a
current line and number of lines in the edit buffer of 1 in the
same situation. POSIX.1‐2008 does not permit this discrepancy,
instead requiring that a message be displayed indicating that the
file is empty.
Global
The two-pass operation of the global and v commands is not
intended to imply implementation, only the required result of the
operation.
The current line and column are set as specified for the
individual ex commands. This requirement is cumulative; that is,
the current line and column must track across all the commands
executed by the global or v commands.
Insert
See the RATIONALE for the append command.
Historically, insert could not be used with an address of zero;
that is, not when the edit buffer was empty. POSIX.1‐2008
requires that this command behave consistently with the append
command.
Join
The action of the join command in relation to the special
characters is only defined for the POSIX locale because the
correct amount of white space after a period varies; in Japanese
none is required, in French only a single space, and so on.
List
The historical output of the list command was potentially
ambiguous. The standard developers believed correcting this to be
more important than adhering to historical practice, and
POSIX.1‐2008 requires unambiguous output.
Map
Historically, command mode maps only applied to command names;
for example, if the character 'x' was mapped to 'y', the command
fx searched for the 'x' character, not the 'y' character.
POSIX.1‐2008 requires this behavior. Historically, entering
<control>‐V as the first character of a vi command was an error.
Several implementations have extended the semantics of vi such
that <control>‐V means that the subsequent command character is
not mapped. This is permitted, but not required, by POSIX.1‐2008.
Regardless, using <control>‐V to escape the second or later
character in a sequence of characters that might match a map
command, or any character in text input mode, is historical
practice, and stops the entered keys from matching a map.
POSIX.1‐2008 requires conformance to historical practice.
Historical implementations permitted digits to be used as a map
command lhs, but then ignored the map. POSIX.1‐2008 requires that
the mapped digits not be ignored.
The historical implementation of the map command did not permit
map commands that were more than a single character in length if
the first character was printable. This behavior is permitted,
but not required, by POSIX.1‐2008.
Historically, mapped characters were remapped unless the remap
edit option was not set, or the prefix of the mapped characters
matched the mapping characters; for example, in the map:
:map ab abcd
the characters "ab" were used as is and were not remapped, but
the characters "cd" were mapped if appropriate. This can cause
infinite loops in the vi mapping mechanisms. POSIX.1‐2008
requires conformance to historical practice, and that such loops
be interruptible.
Text input maps had the same problems with expanding the lhs for
the ex map! and unmap! command as did the ex abbreviate and
unabbreviate commands. See the RATIONALE for the ex abbreviate
command. POSIX.1‐2008 requires similar modification of some
historical practice for the map and unmap commands, as described
for the abbreviate and unabbreviate commands.
Historically, maps that were subsets of other maps behaved
differently depending on the order in which they were defined.
For example:
:map! ab short
:map! abc long
would always translate the characters "ab" to "short", regardless
of how fast the characters "abc" were entered. If the entry order
was reversed:
:map! abc long
:map! ab short
the characters "ab" would cause the editor to pause, waiting for
the completing 'c' character, and the characters might never be
mapped to "short". For consistency and simplicity of
specification, POSIX.1‐2008 requires that the shortest match be
used at all times.
The length of time the editor spends waiting for the characters
to complete the lhs is unspecified because the timing
capabilities of systems are often inexact and variable, and it
may depend on other factors such as the speed of the connection.
The time should be long enough for the user to be able to
complete the sequence, but not long enough for the user to have
to wait. Some implementations of vi have added a keytime option,
which permits users to set the number of 0,1 seconds the editor
waits for the completing characters. Because mapped terminal
function and cursor keys tend to start with an <ESC> character,
and <ESC> is the key ending vi text input mode, maps starting
with <ESC> characters are generally exempted from this timeout
period, or, at least timed out differently.
Mark
Historically, users were able to set the ``previous context''
marks explicitly. In addition, the ex commands '' and '` and the
vi commands '', ``, `', and '` all referred to the same mark. In
addition, the previous context marks were not set if the command,
with which the address setting the mark was associated, failed.
POSIX.1‐2008 requires conformance to historical practice.
Historically, if marked lines were deleted, the mark was also
deleted, but would reappear if the change was undone.
POSIX.1‐2008 requires conformance to historical practice.
The description of the special events that set the ` and ' marks
matches historical practice. For example, historically the
command /a/,/b/ did not set the ` and ' marks, but the command
/a/,/b/delete did.
Next
Historically, any ex command could be entered as a +command
argument to the next command, although some (for example, insert
and append) were known to confuse historical implementations.
POSIX.1‐2008 requires that any command be permitted and that it
behave as specified. The next command can accept more than one
file, so usage such as:
next `ls [abc] `
is valid; it need not be valid for the edit or read commands, for
example, because they expect only one filename.
Historically, the next command behaved differently from the
:rewind command in that it ignored the force flag if the
autowrite flag was set. For consistency, POSIX.1‐2008 does not
permit this behavior.
Historically, the next command positioned the cursor as if the
file had never been edited before, regardless. POSIX.1‐2008 does
not permit this behavior, for consistency with the edit command.
Implementations wanting to provide a counterpart to the next
command that edited the previous file have used the command
prev[ious], which takes no file argument. POSIX.1‐2008 does not
require this command.
Open
Historically, the open command would fail if the open edit option
was not set. POSIX.1‐2008 does not mention the open edit option
and does not require this behavior. Some historical
implementations do not permit entering open mode from open or
visual mode, only from ex mode. For consistency, POSIX.1‐2008
does not permit this behavior.
Historically, entering open mode from the command line (that is,
vi +open) resulted in anomalous behaviors; for example, the ex
file and set commands, and the vi command <control>‐G did not
work. For consistency, POSIX.1‐2008 does not permit this
behavior.
Historically, the open command only permitted '/' characters to
be used as the search pattern delimiter. For consistency,
POSIX.1‐2008 requires that the search delimiters used by the s,
global, and v commands be accepted as well.
Preserve
The preserve command does not historically cause the file to be
considered unmodified for the purposes of future commands that
may exit the editor. POSIX.1‐2008 requires conformance to
historical practice.
Historical documentation stated that mail was not sent to the
user when preserve was executed; however, historical
implementations did send mail in this case. POSIX.1‐2008 requires
conformance to the historical implementations.
Print
The writing of NUL by the print command is not specified as a
special case because the standard developers did not want to
require ex to support NUL characters. Historically, characters
were displayed using the ARPA standard mappings, which are as
follows:
1. Printable characters are left alone.
2. Control characters less than \177 are represented as '^'
followed by the character offset from the '@' character in
the ASCII map; for example, \007 is represented as '^G'.
3. \177 is represented as '^' followed by '?'.
The display of characters having their eighth bit set was less
standard. Existing implementations use hex (0x00), octal (\000),
and a meta-bit display. (The latter displayed bytes that had
their eighth bit set as the two characters "M-" followed by the
seven-bit display as described above.) The latter probably has
the best claim to historical practice because it was used for the
-v option of 4 BSD and 4 BSD-derived versions of the cat utility
since 1980.
No specific display format is required by POSIX.1‐2008.
Explicit dependence on the ASCII character set has been avoided
where possible, hence the use of the phrase an ``implementation-
defined multi-character sequence'' for the display of non-
printable characters in preference to the historical usage of,
for instance, "^I" for the <tab>. Implementations are encouraged
to conform to historical practice in the absence of any strong
reason to diverge.
Historically, all ex commands beginning with the letter 'p' could
be entered using capitalized versions of the commands; for
example, P[rint], Pre[serve], and Pu[t] were all valid command
names. POSIX.1‐2008 permits, but does not require, this
historical practice because capital forms of the commands are
used by some implementations for other purposes.
Put
Historically, an ex put command, executed from open or visual
mode, was the same as the open or visual mode P command, if the
buffer was named and was cut in character mode, and the same as
the p command if the buffer was named and cut in line mode. If
the unnamed buffer was the source of the text, the entire line
from which the text was taken was usually put, and the buffer was
handled as if in line mode, but it was possible to get extremely
anomalous behavior. In addition, using the Q command to switch
into ex mode, and then doing a put often resulted in errors as
well, such as appending text that was unrelated to the (supposed)
contents of the buffer. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit these behaviors. All
ex put commands are required to operate in line mode, and the
contents of the buffers are not altered by changing the mode of
the editor.
Read
Historically, an ex read command executed from open or visual
mode, executed in an empty file, left an empty line as the first
line of the file. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
Historically, a read in open or visual mode from a program left
the cursor at the last line read in, not the first. For
consistency, POSIX.1‐2008 does not permit this behavior.
Historical implementations of ex were unable to undo read
commands that read from the output of a program. For consistency,
POSIX.1‐2008 does not permit this behavior.
Historically, the ex and vi message after a successful read or
write command specified ``characters'', not ``bytes''.
POSIX.1‐2008 requires that the number of bytes be displayed, not
the number of characters, because it may be difficult in multi-
byte implementations to determine the number of characters read.
Implementations are encouraged to clarify the message displayed
to the user.
Historically, reads were not permitted on files other than type
regular, except that FIFO files could be read (probably only
because they did not exist when ex and vi were originally
written). Because the historical ex evaluated read! and read !
equivalently, there can be no optional way to force the read.
POSIX.1‐2008 permits, but does not require, this behavior.
Recover
Some historical implementations of the editor permitted users to
recover the edit buffer contents from a previous edit session,
and then exit without saving those contents (or explicitly
discarding them). The intent of POSIX.1‐2008 in requiring that
the edit buffer be treated as already modified is to prevent this
user error.
Rewind
Historical implementations supported the rewind command when the
user was editing the first file in the list; that is, the file
that the rewind command would edit. POSIX.1‐2008 requires
conformance to historical practice.
Substitute
Historically, ex accepted an r option to the s command. The
effect of the r option was to use the last regular expression
used in any command as the pattern, the same as the ~ command.
The r option is not required by POSIX.1‐2008. Historically, the c
and g options were toggled; for example, the command :s/abc/def/
was the same as s/abc/def/ccccgggg. For simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
The tilde command is often used to replace the last search RE.
For example, in the sequence:
s/red/blue/
/green
~
the ~ command is equivalent to:
s/green/blue/
Historically, ex accepted all of the following forms:
s/abc/def/
s/abc/def
s/abc/
s/abc
POSIX.1‐2008 requires conformance to this historical practice.
The s command presumes that the '^' character only occupies a
single column in the display. Much of the ex and vi specification
presumes that the <space> only occupies a single column in the
display. There are no known character sets for which this is not
true.
Historically, the final column position for the substitute
commands was based on previous column movements; a search for a
pattern followed by a substitution would leave the column
position unchanged, while a 0 command followed by a substitution
would change the column position to the first non-<blank>. For
consistency and simplicity of specification, POSIX.1‐2008
requires that the final column position always be set to the
first non-<blank>.
Set
Historical implementations redisplayed all of the options for
each occurrence of the all keyword. POSIX.1‐2008 permits, but
does not require, this behavior.
Tag
No requirement is made as to where ex and vi shall look for the
file referenced by the tag entry. Historical practice has been to
look for the path found in the tags file, based on the current
directory. A useful extension found in some implementations is to
look based on the directory containing the tags file that held
the entry, as well. No requirement is made as to which reference
for the tag in the tags file is used. This is deliberate, in
order to permit extensions such as multiple entries in a tags
file for a tag.
Because users often specify many different tags files, some of
which need not be relevant or exist at any particular time,
POSIX.1‐2008 requires that error messages about problem tags
files be displayed only if the requested tag is not found, and
then, only once for each time that the tag edit option is
changed.
The requirement that the current edit buffer be unmodified is
only necessary if the file indicated by the tag entry is not the
same as the current file (as defined by the current pathname).
Historically, the file would be reloaded if the filename had
changed, as well as if the filename was different from the
current pathname. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior,
requiring that the name be the only factor in the decision.
Historically, vi only searched for tags in the current file from
the current cursor to the end of the file, and therefore, if the
wrapscan option was not set, tags occurring before the current
cursor were not found. POSIX.1‐2008 considers this a bug, and
implementations are required to search for the first occurrence
in the file, regardless.
Undo
The undo description deliberately uses the word ``modified''. The
undo command is not intended to undo commands that replace the
contents of the edit buffer, such as edit, next, tag, or recover.
Cursor positioning after the undo command was inconsistent in the
historical vi, sometimes attempting to restore the original
cursor position (global, undo, and v commands), and sometimes, in
the presence of maps, placing the cursor on the last line added
or changed instead of the first. POSIX.1‐2008 requires a
simplified behavior for consistency and simplicity of
specification.
Version
The version command cannot be exactly specified since there is no
widely-accepted definition of what the version information should
contain. Implementations are encouraged to do something
reasonably intelligent.
Write
Historically, the ex and vi message after a successful read or
write command specified ``characters'', not ``bytes''.
POSIX.1‐2008 requires that the number of bytes be displayed, not
the number of characters because it may be difficult in multi-
byte implementations to determine the number of characters
written. Implementations are encouraged to clarify the message
displayed to the user.
Implementation-defined tests are permitted so that
implementations can make additional checks; for example, for
locks or file modification times.
Historically, attempting to append to a nonexistent file caused
an error. It has been left unspecified in POSIX.1‐2008 to permit
implementations to let the write succeed, so that the append
semantics are similar to those of the historical csh.
Historical vi permitted empty edit buffers to be written.
However, since the way vi got around dealing with ``empty'' files
was to always have a line in the edit buffer, no matter what, it
wrote them as files of a single, empty line. POSIX.1‐2008 does
not permit this behavior.
Historically, ex restored standard output and standard error to
their values as of when ex was invoked, before writes to programs
were performed. This could disturb the terminal configuration as
well as be a security issue for some terminals. POSIX.1‐2008 does
not permit this, requiring that the program output be captured
and displayed as if by the ex print command.
Adjust Window
Historically, the line count was set to the value of the scroll
option if the type character was end-of-file. This feature was
broken on most historical implementations long ago, however, and
is not documented anywhere. For this reason, POSIX.1‐2008 is
resolutely silent.
Historically, the z command was <blank>-sensitive and z + and z -
did different things than z+ and z- because the type could not be
distinguished from a flag. (The commands z . and z = were
historically invalid.) POSIX.1‐2008 requires conformance to this
historical practice.
Historically, the z command was further <blank>-sensitive in that
the count could not be <blank>-delimited; for example, the
commands z= 5 and z- 5 were also invalid. Because the count is
not ambiguous with respect to either the type character or the
flags, this is not permitted by POSIX.1‐2008.
Escape
Historically, ex filter commands only read the standard output of
the commands, letting standard error appear on the terminal as
usual. The vi utility, however, read both standard output and
standard error. POSIX.1‐2008 requires the latter behavior for
both ex and vi, for consistency.
Shift Left and Shift Right
Historically, it was possible to add shift characters to increase
the effect of the command; for example, <<< outdented (or >>>
indented) the lines 3 levels of indentation instead of the
default 1. POSIX.1‐2008 requires conformance to historical
practice.
<control>‐D
Historically, the <control>‐D command erased the prompt,
providing the user with an unbroken presentation of lines from
the edit buffer. This is not required by POSIX.1‐2008;
implementations are encouraged to provide it if possible.
Historically, the <control>‐D command took, and then ignored, a
count. POSIX.1‐2008 does not permit this behavior.
Write Line Number
Historically, the ex = command, when executed in ex mode in an
empty edit buffer, reported 0, and from open or visual mode,
reported 1. For consistency and simplicity of specification,
POSIX.1‐2008 does not permit this behavior.
Execute
Historically, ex did not correctly handle the inclusion of text
input commands (that is, append, insert, and change) in executed
buffers. POSIX.1‐2008 does not permit this exclusion for
consistency.
Historically, the logical contents of the buffer being executed
did not change if the buffer itself were modified by the commands
being executed; that is, buffer execution did not support self-
modifying code. POSIX.1‐2008 requires conformance to historical
practice.
Historically, the @ command took a range of lines, and the @
buffer was executed once per line, with the current line ('.')
set to each specified line. POSIX.1‐2008 requires conformance to
historical practice.
Some historical implementations did not notice if errors occurred
during buffer execution. This, coupled with the ability to
specify a range of lines for the ex @ command, makes it trivial
to cause them to drop core. POSIX.1‐2008 requires that
implementations stop buffer execution if any error occurs, if the
specified line doesn't exist, or if the contents of the edit
buffer itself are replaced (for example, the buffer executes the
ex :edit command).
Regular Expressions in ex
Historical practice is that the characters in the replacement
part of the last s command—that is, those matched by entering a
'~' in the regular expression—were not further expanded by the
regular expression engine. So, if the characters contained the
string "a.," they would match 'a' followed by ".," and not 'a'
followed by any character. POSIX.1‐2008 requires conformance to
historical practice.
Edit Options in ex
The following paragraphs describe the historical behavior of some
edit options that were not, for whatever reason, included in
POSIX.1‐2008. Implementations are strongly encouraged to only
use these names if the functionality described here is fully
supported.
extended The extended edit option has been used in some
implementations of vi to provide extended regular
expressions instead of basic regular expressions This
option was omitted from POSIX.1‐2008 because it is not
widespread historical practice.
flash The flash edit option historically caused the screen to
flash instead of beeping on error. This option was
omitted from POSIX.1‐2008 because it is not found in
some historical implementations.
hardtabs The hardtabs edit option historically defined the
number of columns between hardware tab settings. This
option was omitted from POSIX.1‐2008 because it was
believed to no longer be generally useful.
modeline The modeline (sometimes named modelines) edit option
historically caused ex or vi to read the five first and
last lines of the file for editor commands. This
option is a security problem, and vendors are strongly
encouraged to delete it from historical
implementations.
open The open edit option historically disallowed the ex
open and visual commands. This edit option was omitted
because these commands are required by POSIX.1‐2008.
optimize The optimize edit option historically expedited text
throughput by setting the terminal to not do automatic
<carriage-return> characters when printing more than
one logical line of output. This option was omitted
from POSIX.1‐2008 because it was intended for terminals
without addressable cursors, which are rarely, if ever,
still used.
ruler The ruler edit option has been used in some
implementations of vi to present a current row/column
ruler for the user. This option was omitted from
POSIX.1‐2008 because it is not widespread historical
practice.
sourceany The sourceany edit option historically caused ex or vi
to source start-up files that were owned by users other
than the user running the editor. This option is a
security problem, and vendors are strongly encouraged
to remove it from their implementations.
timeout The timeout edit option historically enabled the (now
standard) feature of only waiting for a short period
before returning keys that could be part of a macro.
This feature was omitted from POSIX.1‐2008 because its
behavior is now standard, it is not widely useful, and
it was rarely documented.
verbose The verbose edit option has been used in some
implementations of vi to cause vi to output error
messages for common errors; for example, attempting to
move the cursor past the beginning or end of the line
instead of only alerting the screen. (The historical vi
only alerted the terminal and presented no message for
such errors. The historical editor option terse did not
select when to present error messages, it only made
existing error messages more or less verbose.) This
option was omitted from POSIX.1‐2008 because it is not
widespread historical practice; however, implementors
are encouraged to use it if they wish to provide error
messages for naive users.
wraplen The wraplen edit option has been used in some
implementations of vi to specify an automatic margin
measured from the left margin instead of from the right
margin. This is useful when multiple screen sizes are
being used to edit a single file. This option was
omitted from POSIX.1‐2008 because it is not widespread
historical practice; however, implementors are
encouraged to use it if they add this functionality.
autoindent, ai
Historically, the command 0a did not do any autoindentation,
regardless of the current indentation of line 1. POSIX.1‐2008
requires that any indentation present in line 1 be used.
autoprint, ap
Historically, the autoprint edit option was not completely
consistent or based solely on modifications to the edit buffer.
Exceptions were the read command (when reading from a file, but
not from a filter), the append, change, insert, global, and v
commands, all of which were not affected by autoprint, and the
tag command, which was affected by autoprint. POSIX.1‐2008
requires conformance to historical practice.
Historically, the autoprint option only applied to the last of
multiple commands entered using <vertical-line> delimiters; for
example, delete <newline> was affected by autoprint, but
delete|version <newline> was not. POSIX.1‐2008 requires
conformance to historical practice.
autowrite, aw
Appending the '!' character to the ex next command to avoid
performing an automatic write was not supported in historical
implementations. POSIX.1‐2008 requires that the behavior match
the other ex commands for consistency.
ignorecase, ic
Historical implementations of case-insensitive matching (the
ignorecase edit option) lead to counter-intuitive situations when
uppercase characters were used in range expressions.
Historically, the process was as follows:
1. Take a line of text from the edit buffer.
2. Convert uppercase to lowercase in text line.
3. Convert uppercase to lowercase in regular expressions, except
in character class specifications.
4. Match regular expressions against text.
This would mean that, with ignorecase in effect, the text:
The cat sat on the mat
would be matched by
/^the/
but not by:
/^[A-Z]he/
For consistency with other commands implementing regular
expressions, POSIX.1‐2008 does not permit this behavior.
paragraphs, para
The ISO POSIX‐2:1993 standard made the default paragraphs and
sections edit options implementation-defined, arguing they were
historically oriented to the UNIX system troff text formatter,
and a ``portable user'' could use the {, }, [[, ]], (, and )
commands in open or visual mode and have the cursor stop in
unexpected places. POSIX.1‐2008 specifies their values in the
POSIX locale because the unusual grouping (they only work when
grouped into two characters at a time) means that they cannot be
used for general-purpose movement, regardless.
readonly
Implementations are encouraged to provide the best possible
information to the user as to the read-only status of the file,
with the exception that they should not consider the current
special privileges of the process. This provides users with a
safety net because they must force the overwrite of read-only
files, even when running with additional privileges.
The readonly edit option specification largely conforms to
historical practice. The only difference is that historical
implementations did not notice that the user had set the readonly
edit option in cases where the file was already marked read-only
for some reason, and would therefore reinitialize the readonly
edit option the next time the contents of the edit buffer were
replaced. This behavior is disallowed by POSIX.1‐2008.
report
The requirement that lines copied to a buffer interact
differently than deleted lines is historical practice. For
example, if the report edit option is set to 3, deleting 3 lines
will cause a report to be written, but 4 lines must be copied
before a report is written.
The requirement that the ex global, v, open, undo, and visual
commands present reports based on the total number of lines added
or deleted during the command execution, and that commands
executed by the global and v commands not present reports, is
historical practice. POSIX.1‐2008 extends historical practice by
requiring that buffer execution be treated similarly. The reasons
for this are two-fold. Historically, only the report by the last
command executed from the buffer would be seen by the user, as
each new report would overwrite the last. In addition, the
standard developers believed that buffer execution had more in
common with global and v commands than it did with other ex
commands, and should behave similarly, for consistency and
simplicity of specification.
showmatch, sm
The length of time the cursor spends on the matching character is
unspecified because the timing capabilities of systems are often
inexact and variable. The time should be long enough for the user
to notice, but not long enough for the user to become annoyed.
Some implementations of vi have added a matchtime option that
permits users to set the number of 0,1 second intervals the
cursor pauses on the matching character.
showmode
The showmode option has been used in some historical
implementations of ex and vi to display the current editing mode
when in open or visual mode. The editing modes have generally
included ``command'' and ``input'', and sometimes other modes
such as ``replace'' and ``change''. The string was usually
displayed on the bottom line of the screen at the far right-hand
corner. In addition, a preceding '*' character often denoted
whether the contents of the edit buffer had been modified. The
latter display has sometimes been part of the showmode option,
and sometimes based on another option. This option was not
available in the 4 BSD historical implementation of vi, but was
viewed as generally useful, particularly to novice users, and is
required by POSIX.1‐2008.
The smd shorthand for the showmode option was not present in all
historical implementations of the editor. POSIX.1‐2008 requires
it, for consistency.
Not all historical implementations of the editor displayed a mode
string for command mode, differentiating command mode from text
input mode by the absence of a mode string. POSIX.1‐2008 permits
this behavior for consistency with historical practice, but
implementations are encouraged to provide a display string for
both modes.
slowopen
Historically, the slowopen option was automatically set if the
terminal baud rate was less than 1200 baud, or if the baud rate
was 1200 baud and the redraw option was not set. The slowopen
option had two effects. First, when inserting characters in the
middle of a line, characters after the cursor would not be pushed
ahead, but would appear to be overwritten. Second, when creating
a new line of text, lines after the current line would not be
scrolled down, but would appear to be overwritten. In both cases,
ending text input mode would cause the screen to be refreshed to
match the actual contents of the edit buffer. Finally, terminals
that were sufficiently intelligent caused the editor to ignore
the slowopen option. POSIX.1‐2008 permits most historical
behavior, extending historical practice to require slowopen
behaviors if the edit option is set by the user.
tags
The default path for tags files is left unspecified as
implementations may have their own tags implementations that do
not correspond to the historical ones. The default tags option
value should probably at least include the file ./tags.
term
Historical implementations of ex and vi ignored changes to the
term edit option after the initial terminal information was
loaded. This is permitted by POSIX.1‐2008; however,
implementations are encouraged to permit the user to modify their
terminal type at any time.
terse
Historically, the terse edit option optionally provided a
shorter, less descriptive error message, for some error messages.
This is permitted, but not required, by POSIX.1‐2008.
Historically, most common visual mode errors (for example, trying
to move the cursor past the end of a line) did not result in an
error message, but simply alerted the terminal. Implementations
wishing to provide messages for novice users are urged to do so
based on the edit option verbose, and not terse.
window
In historical implementations, the default for the window edit
option was based on the baud rate as follows:
1. If the baud rate was less than 1200, the edit option w300 set
the window value; for example, the line:
set w300=12
would set the window option to 12 if the baud rate was less
than 1200.
2. If the baud rate was equal to 1200, the edit option w1200 set
the window value.
3. If the baud rate was greater than 1200, the edit option w9600
set the window value.
The w300, w1200, and w9600 options do not appear in POSIX.1‐2008
because of their dependence on specific baud rates.
In historical implementations, the size of the window displayed
by various commands was related to, but not necessarily the same
as, the window edit option. For example, the size of the window
was set by the ex command visual 10, but it did not change the
value of the window edit option. However, changing the value of
the window edit option did change the number of lines that were
displayed when the screen was repainted. POSIX.1‐2008 does not
permit this behavior in the interests of consistency and
simplicity of specification, and requires that all commands that
change the number of lines that are displayed do it by setting
the value of the window edit option.
wrapmargin, wm
Historically, the wrapmargin option did not affect maps inserting
characters that also had associated counts; for example
:map K 5aABC DEF. Unfortunately, there are widely used maps that
depend on this behavior. For consistency and simplicity of
specification, POSIX.1‐2008 does not permit this behavior.
Historically, wrapmargin was calculated using the column display
width of all characters on the screen. For example, an
implementation using "^I" to represent <tab> characters when the
list edit option was set, where '^' and 'I' each took up a single
column on the screen, would calculate the wrapmargin based on a
value of 2 for each <tab>. The number edit option similarly
changed the effective length of the line as well. POSIX.1‐2008
requires conformance to historical practice.
Earlier versions of this standard allowed for implementations
with bytes other than eight bits, but this has been modified in
this version.
None.
Section 2.9.1.1, Command Search and Execution, ctags(1p), ed(1p),
sed(1p), sh(1p), stty(1p), vi(1p)
The Base Definitions volume of POSIX.1‐2017, Table 5-1, Escape
Sequences and Associated Actions, Chapter 8, Environment
Variables, Section 9.3, Basic Regular Expressions, Section 12.2,
Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, access(3p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 EX(1P)
Pages that refer to this page: ed(1p), more(1p), vi(1p)
|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|