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.TH DIRNAME 3  2000-12-14 "GNU" "Linux Programmer's Manual"
.SH NAME
dirname, basename \- Parse pathname components
.SH SYNOPSIS
.nf
.B #include <libgen.h>
.sp
.BI "char *dirname(char *" path );
.nl
.BI "char *basename(char *" path );
.fi
.SH DESCRIPTION
Warning: there are two different functions
.B basename
- see below.
.LP
The functions
.B dirname
and
.B basename
break a null-terminated pathname string into directory 
and filename components.  
In the usual case, 
.B dirname
returns the string up to, but not including, the final '/', and
.B basename
returns the component following the final '/'.
Trailing '/' characters are not counted as part of the pathname.
.PP
If 
.I path
does not contain a slash,
.B dirname
returns the string "." while
.B basename
returns a copy of
.IR path .
If 
.I path
is the string "/", then both
.B dirname
and 
.B basename
return the string "/".
If 
.I path
is a NULL pointer or points to an empty string, then both
.B dirname
and
.B basename
return the string ".".
.PP
Concatenating the string returned by
.BR dirname ,
a "/", and the string returned by 
.B basename
yields a complete pathname.
.PP
Both 
.B dirname
and
.B basename
may modify the contents of 
.IR path , 
so copies should be passed to these functions.
Furthermore, 
.B dirname
and
.B basename
may return pointers to statically allocated memory
which may be overwritten by subsequent calls.
.PP
The following list of examples (taken from SUSv2)
shows the strings returned by 
.B dirname
and
.B basename
for different paths:
.sp
.nf
.B 
path  		dirname		basename
"/usr/lib"	"/usr"		"lib"
"/usr/"		"/"  		"usr"
"usr"		"."  		"usr"
"/"  		"/"  		"/"
"."  		"."  		"."
".."  		"."  		".."
.fi
.SH EXAMPLE
.RS
.nf
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);
.fi
.RE
.SH "RETURN VALUE"
Both 
.B dirname
and
.B basename
return pointers to null-terminated strings.
.SH NOTES
There are two different versions of
.B basename
- the POSIX version described above, and the GNU version one gets
after
.br
.nf
.B "  #define _GNU_SOURCE"
.br
.B "  #include <string.h>"
.fi
The GNU version never modifies its argument, and returns the
empty string when
.I path
has a trailing slash, and in particular also when it is "/".
There is no GNU version of
.BR dirname .
.LP
With glibc, one gets the POSIX version of
.B basename
when <libgen.h> is included, and the GNU version otherwise.
.SH 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
.B dirname
did not correctly handle pathnames with trailing '/' characters,
and generated a segfault if given a NULL argument.
.SH "CONFORMING TO"
POSIX 1003.1-2001
.SH "SEE ALSO"
.BR basename (1),
.BR dirname (1)