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, 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

       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  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

       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, applications 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 prepared 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 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 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 proposals 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(P)