DIRNAME(3) Linux Programmer's Manual DIRNAME(3)NAME
dirname, basename - 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
copies should be passed to these functions. Furthermore, dirname() and
basename() may return pointers to statically allocated memory which may
be overwritten by subsequent calls.
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"
"/" "/" "/"
"." "." "."
".." "." ".."
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);
RETURN VALUE
Both dirname() and basename() return pointers to null-terminated
strings.
NOTES
There are two different versions of basename() - the POSIX version
described above, and the GNU version, which one gets after
#define _GNU_SOURCE
#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 of the POSIX versions of these functions
they modify their argument, and segfault when called with a static
string like "/usr/". Before glibc 2.2.1, the glibc version of
dirname() did not correctly handle pathnames with trailing '/' characā
ters, and generated a segfault if given a NULL argument.
CONFORMING TO
POSIX.1-2001
SEE ALSObasename(1), dirname(1)GNU 2000-12-14 DIRNAME(3)