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

DIRNAME(1P)               POSIX Programmer's Manual              DIRNAME(1P)

PROLOG         top

       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.

NAME         top

       dirname — return the directory portion of a pathname

SYNOPSIS         top

       dirname string

DESCRIPTION         top

       The string operand shall be treated as a pathname, as defined in the
       Base Definitions volume of POSIX.1‐2008, Section 3.267, 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.

OPTIONS         top

       None.

OPERANDS         top

       The following operand shall be supported:

       string    A string.

STDIN         top

       Not used.

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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.1‐2008, 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.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       The dirname utility shall write a line to the standard output in the
       following format:

           "%s\n", <resulting string>

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       None.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful completion.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

       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.

EXAMPLES         top

                         ┌─────────────────┬─────────────┐
                         │    Command      Results   │
                         ├─────────────────┼─────────────┤
                         │dirname /        │ /           │
                         │dirname //       │ / or //     │
                         │dirname /a/b/    │ /a          │
                         │dirname //a//b// │ //a         │
                         │dirname          │ Unspecified │
                         │dirname a        │ . ($? = 0)  │
                         │dirname ""       │ . ($? = 0)  │
                         │dirname /a       │ /           │
                         │dirname /a/b     │ /a          │
                         │dirname a/ba           │
                         └─────────────────┴─────────────┘
       See also the examples for the basename utility.

RATIONALE         top

       The dirname utility originated in System III. It has evolved through
       the System V releases to a version that matches the requirements
       specified in this description in System V Release 3. 4.3 BSD and
       earlier versions did not include dirname.

       The behaviors of basename and dirname in this volume of POSIX.1‐2008
       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.1‐2008, Section
       3.267, Pathname allows trailing <slash> characters. The basename and
       dirname utilities have to specify consistent handling for all valid
       pathnames.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Section 2.5, Parameters and Variables, basename(1p)

       The Base Definitions volume of POSIX.1‐2008, Section 3.267, Pathname,
       Chapter 8, Environment Variables

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/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                 2013                         DIRNAME(1P)

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