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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 |
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CHOWN(1P) POSIX Programmer's Manual CHOWN(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.
chown — change the file ownership
chown [-h] owner[:group] file...
chown -R [-H|-L|-P] owner[:group] file...
The chown utility shall set the user ID of the file named by each
file operand to the user ID specified by the owner operand.
For each file operand, or, if the -R option is used, each file
encountered while walking the directory trees specified by the
file operands, the chown utility shall perform actions equivalent
to the chown() function defined in the System Interfaces volume
of POSIX.1‐2017, called with the following arguments:
1. The file operand shall be used as the path argument.
2. The user ID indicated by the owner portion of the first
operand shall be used as the owner argument.
3. If the group portion of the first operand is given, the group
ID indicated by it shall be used as the group argument;
otherwise, the group ownership shall not be changed.
Unless chown is invoked by a process with appropriate privileges,
the set-user-ID and set-group-ID bits of a regular file shall be
cleared upon successful completion; the set-user-ID and set-
group-ID bits of other file types may be cleared.
The chown utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported by the implementation:
-h For each file operand that names a file of type
symbolic link, chown shall attempt to set the user ID
of the symbolic link. If a group ID was specified, for
each file operand that names a file of type symbolic
link, chown shall attempt to set the group ID of the
symbolic link.
-H If the -R option is specified and a symbolic link
referencing a file of type directory is specified on
the command line, chown shall change the user ID (and
group ID, if specified) of the directory referenced by
the symbolic link and all files in the file hierarchy
below it.
-L If the -R option is specified and a symbolic link
referencing a file of type directory is specified on
the command line or encountered during the traversal of
a file hierarchy, chown shall change the user ID (and
group ID, if specified) of the directory referenced by
the symbolic link and all files in the file hierarchy
below it.
-P If the -R option is specified and a symbolic link is
specified on the command line or encountered during the
traversal of a file hierarchy, chown shall change the
owner ID (and group ID, if specified) of the symbolic
link. The chown utility shall not follow the symbolic
link to any other part of the file hierarchy.
-R Recursively change file user and group IDs. For each
file operand that names a directory, chown shall change
the user ID (and group ID, if specified) of the
directory and all files in the file hierarchy below it.
Unless a -H, -L, or -P option is specified, it is
unspecified which of these options will be used as the
default.
Specifying more than one of the mutually-exclusive options -H,
-L, and -P shall not be considered an error. The last option
specified shall determine the behavior of the utility.
The following operands shall be supported:
owner[:group]
A user ID and optional group ID to be assigned to file.
The owner portion of this operand shall be a user name
from the user database or a numeric user ID. Either
specifies a user ID which shall be given to each file
named by one of the file operands. If a numeric owner
operand exists in the user database as a user name, the
user ID number associated with that user name shall be
used as the user ID. Similarly, if the group portion of
this operand is present, it shall be a group name from
the group database or a numeric group ID. Either
specifies a group ID which shall be given to each file.
If a numeric group operand exists in the group database
as a group name, the group ID number associated with
that group name shall be used as the group ID.
file A pathname of a file whose user ID is to be modified.
Not used.
None.
The following environment variables shall affect the execution of
chown:
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_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).
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
Not used.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 The utility executed successfully and all requested changes
were made.
>0 An error occurred.
Default.
The following sections are informative.
Only the owner of a file or the user with appropriate privileges
may change the owner or group of a file.
Some implementations restrict the use of chown to a user with
appropriate privileges.
None.
The System V and BSD versions use different exit status codes.
Some implementations used the exit status as a count of the
number of errors that occurred; this practice is unworkable since
it can overflow the range of valid exit status values. These are
masked by specifying only 0 and >0 as exit values.
The functionality of chown is described substantially through
references to functions in the System Interfaces volume of
POSIX.1‐2017. In this way, there is no duplication of effort
required for describing the interactions of permissions, multiple
groups, and so on.
The 4.3 BSD method of specifying both owner and group was
included in this volume of POSIX.1‐2017 because:
* There are cases where the desired end condition could not be
achieved using the chgrp and chown (that only changed the
user ID) utilities. (If the current owner is not a member of
the desired group and the desired owner is not a member of
the current group, the chown() function could fail unless
both owner and group are changed at the same time.)
* Even if they could be changed independently, in cases where
both are being changed, there is a 100% performance penalty
caused by being forced to invoke both utilities.
The BSD syntax user[.group] was changed to user[:group] in this
volume of POSIX.1‐2017 because the <period> is a valid character
in login names (as specified by the Base Definitions volume of
POSIX.1‐2017, login names consist of characters in the portable
filename character set). The <colon> character was chosen as the
replacement for the <period> character because it would never be
allowed as a character in a user name or group name on historical
implementations.
The -R option is considered by some observers as an undesirable
departure from the historical UNIX system tools approach; since a
tool, find, already exists to recurse over directories, there
seemed to be no good reason to require other tools to have to
duplicate that functionality. However, the -R option was deemed
an important user convenience, is far more efficient than forking
a separate process for each element of the directory hierarchy,
and is in widespread historical use.
None.
chgrp(1p), chmod(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, chown(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 CHOWN(1P)
Pages that refer to this page: chgrp(1p)
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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. |
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