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BASENAME(3) Linux Programmer's Manual BASENAME(3)

NAME

     basename, dirname - parse pathname components

SYNOPSIS

     #include <libgen.h>

     char *dirname(char *path);

     char *basename(char *path);

DESCRIPTION

     Warning: there are two different functions basename() - see below.

     The functions dirname() and basename() break a null-terminated pathname
     string into directory and filename  components.   In  the  usual  case,
     dirname()  returns  the string up to, but not including, the final '/',
     and basename() returns the component following the final '/'.  Trailing
     '/' characters are not counted as part of the pathname.

     If  path  does  not  contain  a slash, dirname() returns the string "."
     while basename() returns a copy of path.  If path is  the  string  "/",
     then both dirname() and basename() return the string "/".  If path is a
     null pointer or points to an empty  string,  then  both  dirname()  and
     basename() return the string ".".

     Concatenating  the  string returned by dirname(), a "/", and the string
     returned by basename() yields a complete pathname.

     Both dirname() and basename() may modify the contents of  path,  so  it
     may be desirable to pass a copy when calling one of these functions.

     These  functions  may  return  pointers  to statically allocated memory
     which may be overwritten by subsequent calls.  Alternatively, they  may
     return  a  pointer to some part of path, so that the string referred to
     by path should not be modified or freed until the pointer  returned  by
     the function is no longer required.

     The  following  list  of  examples (taken from SUSv2) shows the strings
     returned by dirname() and basename() for different paths:

            path       dirname   basename
            /usr/lib   /usr      lib
            /usr/      /         usr
            usr        .         usr
            /          /         /
            .          .         .
            ..         .         ..

RETURN VALUE

     Both  dirname()  and  basename()  return  pointers  to  null-terminated
     strings.  (Do not pass these pointers to free(3).)

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     +----------------------+---------------+---------+
     |Interface             | Attribute     | Value   |
     +----------------------+---------------+---------+
     |basename(), dirname() | Thread safety | MT-Safe |
     +----------------------+---------------+---------+

CONFORMING TO

     POSIX.1-2001, POSIX.1-2008.

NOTES

     There  are  two  different  versions  of basename() - the POSIX version
     described above, and the GNU version, which one gets after

             #define _GNU_SOURCE         /* See feature_test_macros(7)  */
         #include <string.h>

     The  GNU  version  never  modifies  its argument, and returns the empty
     string when path has a trailing slash, and in particular also  when  it
     is "/".  There is no GNU version of dirname().

     With glibc, one gets the POSIX version of basename() when <libgen.h> is
     included, and the GNU version otherwise.

BUGS

     In the glibc implementation, the POSIX versions of these functions mod-
     ify  the  path  argument, and segfault when called with a static string
     such as "/usr/".

     Before glibc 2.2.1, the glibc version of dirname()  did  not  correctly
     handle pathnames with trailing '/' characters, and generated a segfault
     if given a NULL argument.

EXAMPLE

     The following code snippet  demonstrates  the  use  of  basename()  and
     dirname():
         char *dirc, *basec, *bname, *dname; char *path = "/etc/passwd";

         dirc  =  strdup(path); basec = strdup(path); dname = dirname(dirc);
         bname = basename(basec); printf("dirname=%s, basename=%s\n", dname,
         bname);