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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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DIRNAME(1P) POSIX Programmer's Manual DIRNAME(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.
dirname — return the directory portion of a pathname
dirname string
The string operand shall be treated as a pathname, as defined in
the Base Definitions volume of POSIX.1‐2017, Section 3.271,
Pathname. The string string shall be converted to the name of the
directory containing the filename corresponding to the last
pathname component in string, performing actions equivalent to the
following steps in order:
1. If string is //, skip steps 2 to 5.
2. If string consists entirely of <slash> characters, string
shall be set to a single <slash> character. In this case, skip
steps 3 to 8.
3. If there are any trailing <slash> characters in string, they
shall be removed.
4. If there are no <slash> characters remaining in string, string
shall be set to a single <period> character. In this case,
skip steps 5 to 8.
5. If there are any trailing non-<slash> characters in string,
they shall be removed.
6. If the remaining string is //, it is implementation-defined
whether steps 7 and 8 are skipped or processed.
7. If there are any trailing <slash> characters in string, they
shall be removed.
8. If the remaining string is empty, string shall be set to a
single <slash> character.
The resulting string shall be written to standard output.
None.
The following operand shall be supported:
string A string.
Not used.
None.
The following environment variables shall affect the execution of
dirname:
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.
The dirname utility shall write a line to the standard output in
the following format:
"%s\n", <resulting string>
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
The definition of pathname specifies implementation-defined
behavior for pathnames starting with two <slash> characters.
Therefore, applications shall not arbitrarily add <slash>
characters to the beginning of a pathname unless they can ensure
that there are more or less than two or are prepared to deal with
the implementation-defined consequences.
The EXAMPLES section of the basename() function (see the System
Interfaces volume of POSIX.1‐2017, basename(3p)) includes a table
showing examples of the results of processing several sample
pathnames by the basename() and dirname() functions and by the
basename and dirname utilities.
See also the examples for the basename utility.
The behaviors of basename and dirname in this volume of
POSIX.1‐2017 have been coordinated so that when string is a valid
pathname:
$(basename -- "string")
would be a valid filename for the file in the directory:
$(dirname -- "string")
This would not work for the versions of these utilities in early
proposals due to the way processing of trailing <slash> characters
was specified. Consideration was given to leaving processing
unspecified if there were trailing <slash> characters, but this
cannot be done; the Base Definitions volume of POSIX.1‐2017,
Section 3.271, Pathname allows trailing <slash> characters. The
basename and dirname utilities have to specify consistent handling
for all valid pathnames.
None.
Section 2.5, Parameters and Variables, basename(1p)
The Base Definitions volume of POSIX.1‐2017, Section 3.271,
Pathname, Chapter 8, Environment Variables
The System Interfaces volume of POSIX.1‐2017, basename(3p),
dirname(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 DIRNAME(1P)
Pages that refer to this page: basename(1p), dirname(3p)
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HTML rendering created 2025-09-06 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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