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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 dif-
       fer (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, Pathname. The string string shall be converted to the name of  the  direc-
       tory containing the filename corresponding to the last pathname component in string, performing actions equiva-
       lent 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  prece-
              dence 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  exam-
              ple, 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 writ-
              ten 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  trail-
       ing  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, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions 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 Stan-
       dard, 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)