BASENAME
Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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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 aq/aq, and
basename()
returns the component following the final aq/aq.
Trailing aq/aq 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 aq/aq 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
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ATTRIBUTES
-
- CONFORMING TO
-
- NOTES
-
- BUGS
-
- EXAMPLE
-
- SEE ALSO
-
- COLOPHON
-
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