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  reentrant.  A function that is not required to be
       reentrant is not required to 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 static storage that may then be overwritten by subsequent calls 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[PATH_MAX], *pathcopy;
              int fd;
              fgets(path, PATH_MAX, stdin);
              pathcopy = strdup(path);
              chdir(dirname(pathcopy));
              fd = open(basename(path), O_RDONLY);

   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"          "."
                                      "/"            "/"
                                      "."            "."
                                      ".."           "."

   Changing the Current Directory to the Parent Directory
       The  following program fragment reads a pathname, changes the current working directory to
       the parent directory, and opens the file.

              #include <unistd.h>
              #include <limits.h>
              #include <stdio.h>
              #include <fcntl.h>
              #include <string.h>
              #include <libgen.h>
              ...
              char path[PATH_MAX], *pathcopy;
              int fd;
              ...
              fgets(path, PATH_MAX, stdin);
              pathcopy = strdup(path);
              chdir(dirname(pathcopy));
              fd = open(basename(path), O_RDONLY);

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 IEEE Std 1003.1-2001, <libgen.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  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 .