Provided by: manpages-posix_2017a-2_all bug

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 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.

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   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.

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
       <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

       The EXAMPLES section of the basename() function  (see  the  System  Interfaces  volume  of
       POSIX.1‐2017,  basename())  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.

RATIONALE

       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.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.5, Parameters and Variables, basename

       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(), dirname()

COPYRIGHT

       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 .