Originální popis anglicky:
dirname - report the parent directory name of a file pathname
Návod, kniha: POSIX Programmer's Manual
#include <libgen.h>
char *dirname(char *
path);
The
dirname() 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
'/' characters in the path
are not counted as part of the path.
If
path does not contain a
'/' , then
dirname() shall
return a pointer to the string
"." . If
path is a null
pointer or points to an empty string,
dirname() shall return a pointer
to the string
"." .
The
dirname() function need not be reentrant. A function that is not
required to be reentrant is not required to be thread-safe.
The
dirname() function shall return a pointer to a string that is the
parent directory of
path. If
path is a null pointer or points to
an empty string, a pointer to a string
"." is returned.
The
dirname() function may modify the string pointed to by
path,
and may return a pointer to static storage that may then be overwritten by
subsequent calls to
dirname().
No errors are defined.
The following sections are informative.
The following code fragment reads a pathname, changes the current working
directory to the parent directory, and opens the file.
char path[PATH_MAX], *pathcopy;
int fd;
fgets(path, PATH_MAX, stdin);
pathcopy = strdup(path);
chdir(dirname(pathcopy));
fd = open(basename(path), O_RDONLY);
In the following table, the input string is the value pointed to by
path,
and the output string is the return value of the
dirname() function.
| Input String |
Output String |
| "/usr/lib" |
"/usr" |
| "/usr/" |
"/" |
| "usr" |
"." |
| "/" |
"/" |
| "." |
"." |
| ".." |
"." |
The following program fragment reads a pathname, changes the current working
directory to the parent directory, and opens the file.
#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);
The
dirname() and
basename() functions together yield a complete
pathname. The expression
dirname(
path) obtains the pathname of
the directory where
basename(
path) is found.
Since the meaning of the leading
"//" is
implementation-defined,
dirname("
//foo) may return either
"//" or
'/' (but nothing else).
None.
None.
basename() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<libgen.h>
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
.
