This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       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).

       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(3POSIX)

       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.

       No errors are defined.

       Thefollowingsectionsareinformative.

       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.

       None.

       dirname — report the parent directory name of a file pathname

       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.

       None.

       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.

basename()

       The Base Definitions volume of POSIX.1‐2017, <libgen.h>

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

       #include <libgen.h>

       char *dirname(char *path);