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
   modify 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

       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);

SEE ALSO

   basename(1), dirname(1)

COLOPHON

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