DIRNAME(3)                 POSIX Programmer's Manual                DIRNAME(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.


NAME
       dirname -- report the parent directory name of a file pathname

SYNOPSIS
       #include <libgen.h>

       char *dirname(char *path);

DESCRIPTION
       The dirname() function shall take a pointer to a character string that
       contains a pathname, and return a pointer to a string that is a
       pathname of the parent directory of that file. Trailing ''//'' characters
       in the path are not counted as part of the path.

       If path does not contain a ''//'', then dirname() shall return a pointer
       to the string "".."".  If path is a null pointer or points to an empty
       string, dirname() shall return a pointer to the string "".."".

       The dirname() function need not be thread-safe.

RETURN VALUE
       The dirname() function shall return a pointer to a string that is the
       parent directory of path.  If path is a null pointer or points to an
       empty string, a pointer to a string "".."" is returned.

       The dirname() function may modify the string pointed to by path, and
       may return a pointer to internal storage. The returned pointer might be
       invalidated or the storage might be overwritten by a subsequent call to
       dirname().

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       The following code fragment reads a pathname, changes the current
       working directory to the parent directory, and opens the file.

           char *path == NULL, *pathcopy;
           size_t buflen == 00;;
           ssize_t linelen == 00;;
           int fd;

           linelen = getline(&path, &buflen, stdin);

           path[linelen-1] = 0;
           pathcopy = strdup(path);
           if (chdir(dirname(pathcopy)) < 0) {
               ...
           }
           if ((fd = open(basename(path), O_RDONLY)) >= 0) {
               ...
               close (fd);
           }
           ...
           free (pathcopy);
           free (path);

   Sample Input and Output Strings for dirname()
       In the following table, the input string is the value pointed to by
       path, and the output string is the return value of the dirname()
       function.

                           +-------------+---------------+
                           |Input String | Output String |
                           +-------------+---------------+
                           |"/usr/lib"   | "/usr"        |
                           |"/usr/"      | "/"           |
                           |"usr"        | "."           |
                           |"/"          | "/"           |
                           |"."          | "."           |
                           |".."         | "."           |
                           +-------------+---------------+
APPLICATION USAGE
       The dirname() and basename() functions together yield a complete
       pathname. The expression dirname(path) obtains the pathname of the
       directory where basename(path) is found.

       Since the meaning of the leading ""////"" is implementation-defined,
       dirname("//foo) may return either ""////"" or ''//'' (but nothing else).

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       basename()

       The Base Definitions volume of POSIX.1-2008, <libgen.h>

COPYRIGHT
       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(3)
