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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 .