PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

       dirname — report the parent directory name of a file pathname

SYNOPSIS         top

       #include <libgen.h>

       char *dirname(char *path);

DESCRIPTION         top

       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         top

       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         top

       No errors are defined.

       The following sections are informative.

EXAMPLES         top

       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 = 0;
           ssize_t linelen = 0;
           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         top

       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         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       basename(3p)

       The Base Definitions volume of POSIX.1‐2008, libgen.h(0p)

COPYRIGHT         top

       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(3P)