dirname(3p) — Linux manual page

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

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 — 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(3p)) 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(3p)

       The Base Definitions volume of POSIX.1‐2017, libgen.h(0p)

       The Shell and Utilities volume of POSIX.1‐2017, basename(1p),
       dirname(1p)

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(3P)

Pages that refer to this page: libgen.h(0p), basename(1p), dirname(1p), basename(3p)

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