Removes a link from a file.
Syntax |
 |
#include <unistd.h>
int unlink (const char *pathname);
|
Parameters |
|
- pathname
A pointer to a string containing the pathname of a file to unlink (purge). The pathname must be terminated by a null character.
Return Values |
|
- 0
Success.
- -1
An error occurred. The file is not unlinked, and errno is set to indicate the error condition.
Description |
|
The unlink() function removes the link name specified by pathname. It removes the filename pointed to by pathname from the parent directory, then decrements the file link count. When the link count of the file becomes zero and no process has the file open, the file is purged from the system and is no longer accessible.
If one or more processes have the file open when the link count becomes zero, the file is not purged until all references to the file have been closed.
Upon successful completion, unlink() marks for update the st_ctime and st_mtime time fields of the parent directory.
Implementation Considerations |
|
Refer to the EFAULT, EIMPL, EPERM, and ESYSERR error descriptions below.
POSIX/iX does not support using unlink() on directories. Instead, use rmdir() to remove a directory.
POSIX/iX does not support multiple hard links to files or soft links to files or directories.
Every file has a link count of 1 when created. Files being unlinked cause the link count of the file to be decremented from 1 to 0.
Errors |
|
If an error occurs, errno is set to one of the following values:
| EACCES | CAUSE | The calling process either does not have search permission to a component of the pathname or does not have write permission to the parent directory. |
| | ACTION | Make sure that the calling process has search permission for all components of the pathname and write permission to the parent directory. |
| EFAULT | CAUSE | The system detected a NULL or bad address in attempting to use
the pathname parameter or the pathname was not terminated by a null character. |
| | ACTION | Make sure that the pointer is correctly initialized. |
| EIMPL | CAUSE | The pathname begins with two slash characters (//). |
| | ACTION | Do not begin pathnames with two slash characters (//). |
| ENAMETOOLONG | CAUSE | One of the following: The length of the pathname exceeds the {PATH_MAX} limit (defined in the file <limits.h>).
A component of the pathname is longer than {NAME_MAX} (defined in <limits.h>), and {_POSIX_NO_TRUNC} is in effect for that directory.
|
| | ACTION | Make sure that both the component's length and the full pathname
length do not exceed the {NAME_MAX} or {PATH_MAX} limits. |
| ENOENT | CAUSE | The specified file does not exist, or pathname points to an empty string. |
| | ACTION | Specify a valid pathname. |
| ENOTDIR | CAUSE | A component of the pathname is not a directory. |
| | ACTION | Specify a valid pathname. |
| EPERM | CAUSE | The specified file is a directory. |
| | ACTION | Do not attempt to unlink a directory. Use rmdir() instead. |
| ESYSERR | CAUSE | An operating system error has occurred that does not map directly to any of the above errors. |
| | | |
| | ACTION | Examine the MPE/iX error stack for the type of system error. |
See Also |
|
close(), open(), rmdir(), POSIX.1 (Section 5.5.1)
