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. The dirname() function
       shall not perform pathname resolution; the result shall not be affected
       by whether or not path exists or by its file type. Trailing ''//''
       characters in the path that are not also leading ''//'' characters shall
       not be 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 may modify the string pointed to by path, and
       may return a pointer to static storage that may then be overwritten by
       a subsequent call to dirname().

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

RETURN VALUE
       The dirname() function shall return a pointer to a string as described
       above.

       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().  The returned pointer might also be invalidated if the
       calling thread is terminated.

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 = 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);

       The EXAMPLES section of the basename() function (see 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.

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.1-2017, <libgen.h>

       The Shell and Utilities 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 .



IEEE/The Open Group                  2017                           DIRNAME(3)
