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

PROLOG
       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
       dirname - return the directory portion of a pathname
SYNOPSIS
       dirname string
DESCRIPTION
       The string operand shall be treated as a pathname, as  defined  in  the
       Base  Definitions  volume of IEEE Std 1003.1-2001, Section 3.266, Path-
       name. 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
       None.
OPERANDS
       The following operand shall be supported:
       string A string.

STDIN
       Not used.
INPUT FILES
       None.
ENVIRONMENT VARIABLES
       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
              IEEE Std 1003.1-2001,  Section  8.2,  Internationalization Vari-
              ables 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
       Default.
STDOUT
       The dirname utility shall write a line to the standard  output  in  the
       following format:

              "%s\n", <resulting string>
STDERR
       The standard error shall be used only for diagnostic messages.
OUTPUT FILES
       None.
EXTENDED DESCRIPTION
       None.
EXIT STATUS
       The following exit values shall be returned:
        0     Successful completion.
       >0     An error occurred.

CONSEQUENCES OF ERRORS
       Default.
       The following sections are informative.
APPLICATION USAGE
       The  definition  of  pathname specifies implementation-defined behavior
       for pathnames starting with two slash characters.  Therefore,  applica-
       tions  shall not arbitrarily add slashes to the beginning of a pathname
       unless they can ensure that there are more or less than two or are pre-
       pared to deal with the implementation-defined consequences.
EXAMPLES
                           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/b        a
RATIONALE
       The  dirname  utility  originated in System III. It has evolved through
       the System V releases to a version that matches the requirements speci-
       fied  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
       IEEE Std 1003.1-2001  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  pro-
       posals  due  to  the  way processing of trailing slashes was specified.
       Consideration was given to leaving processing unspecified if there were
       trailing  slashes, but this cannot be done; the Base Definitions volume
       of  IEEE Std 1003.1-2001,  Section  3.266,  Pathname  allows   trailing
       slashes.  The basename and dirname utilities have to specify consistent
       handling for all valid pathnames.
FUTURE DIRECTIONS
       None.
SEE ALSO
       basename(), Parameters and Variables
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 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 .

IEEE/The Open Group                  2003                          DIRNAME(1P)