.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "DIRNAME" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" dirname 
.SH NAME
dirname \- report the parent directory name of a file pathname
.SH SYNOPSIS
.LP
\fB#include <libgen.h>
.br
.sp
char *dirname(char *\fP\fIpath\fP\fB); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
The \fIdirname\fP() function shall take a pointer to a character string
that contains a pathname, and return a pointer to a
string that is a pathname of the parent directory of that file. Trailing
\fB'/'\fP characters in the path are not counted as
part of the path.
.LP
If \fIpath\fP does not contain a \fB'/'\fP , then \fIdirname\fP()
shall return a pointer to the string \fB"."\fP . If
\fIpath\fP is a null pointer or points to an empty string, \fIdirname\fP()
shall return a pointer to the string \fB"."\fP
\&.
.LP
The \fIdirname\fP() function need not be reentrant. A function that
is not required to be reentrant is not required to be
thread-safe.
.SH RETURN VALUE
.LP
The \fIdirname\fP() function shall return a pointer to a string that
is the parent directory of \fIpath\fP. If \fIpath\fP is
a null pointer or points to an empty string, a pointer to a string
\fB"."\fP is returned.
.LP
The \fIdirname\fP() function may modify the string pointed to by \fIpath\fP,
and may return a pointer to static storage that
may then be overwritten by subsequent calls to \fIdirname\fP().
.SH ERRORS
.LP
No errors are defined.
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
The following code fragment reads a pathname, changes the current
working directory to the parent directory, and opens the
file.
.sp
.RS
.nf

\fBchar path[PATH_MAX], *pathcopy;
int fd;
fgets(path, PATH_MAX, stdin);
pathcopy = strdup(path);
chdir(dirname(pathcopy));
fd = open(basename(path), O_RDONLY);
\fP
.fi
.RE
.SS Sample Input and Output Strings for dirname()
.LP
In the following table, the input string is the value pointed to by
\fIpath\fP, and the output string is the return value of
the \fIdirname\fP() function.
.TS C
center; l l.
\fBInput String\fP	\fBOutput String\fP
"/usr/lib"	"/usr"
"/usr/"	"/"
"usr"	"."
"/"	"/"
"."	"."
".."	"."
.TE
.SS Changing the Current Directory to the Parent Directory
.LP
The following program fragment reads a pathname, changes the current
working directory to the parent directory, and opens the
file.
.sp
.RS
.nf

\fB#include <unistd.h>
#include <limits.h>
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <libgen.h>
\&...
char path[PATH_MAX], *pathcopy;
int fd;
\&...
fgets(path, PATH_MAX, stdin);
pathcopy = strdup(path);
chdir(dirname(pathcopy));
fd = open(basename(path), O_RDONLY);
\fP
.fi
.RE
.SH APPLICATION USAGE
.LP
The \fIdirname\fP() and \fIbasename\fP() functions together yield
a complete
pathname. The expression \fIdirname\fP(\fIpath\fP) obtains the pathname
of the directory where \fIbasename\fP(\fIpath\fP) is
found.
.LP
Since the meaning of the leading \fB"//"\fP is implementation-defined,
\fIdirname\fP(" \fB//foo\fP) may return either
\fB"//"\fP or \fB'/'\fP (but nothing else).
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIbasename\fP() , the Base Definitions volume of IEEE\ Std\ 1003.1-2001,
\fI<libgen.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .