NAME

unlink − remove directory entry; delete file

SYNOPSIS

#include <unistd.h>

int unlink(const char *path);

DESCRIPTION

unlink() removes the directory entry named by the path name pointed to by path.

When all links to a file have been removed and no process has the file open, the space occupied by the file is freed and the file ceases to exist.  If one or more processes have the file open when the last link is removed, only the directory entry is removed immediately so that processes that do not already have the file open cannot access the file.  After all processes close their references to the file, if there are no more links to the file, the space occupied by the file is then freed and the file ceases to exist. 

RETURN VALUE

Upon successful completion, a value of 0 is returned.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

ERRORS

The named file is unlinked unless one or more of the following are true:

[EACCES] Search permission is denied for a component of the path prefix. 

[EACCES] Write permission is denied on the directory containing the link to be removed. 

[ENOTDIR] A component of the path prefix is not a directory. 

[ENOENT] The named file does not exist (for example, path is null or a component of path does not exist). 

[EPERM] The named file is a directory and the effective user ID of the process is not a user with appropriate privileges. 

[EBUSY] The entry to be unlinked is the mount point for a mounted file system. 

[ETXTBSY] The entry to be unlinked is the last link to a pure procedure (shared text) file that is being executed. 

[EROFS] The directory entry to be unlinked is part of a read-only file system. 

[EFAULT] path points outside the process’s allocated address space.  The reliable detection of this error is implementation dependent. 

[ENAMETOOLONG]
The length of the specified path name exceeds PATH_MAX bytes, or the length of a component of the path name exceeds NAME_MAX bytes while _POSIX_NO_TRUNC is in effect. 

[ELOOP] Too many symbolic links were encountered in translating the path name. 

WARNINGS

If unlink() is used on a directory that is not empty (contains files other than .  and ..), the directory is unlinked, the files become orphans, and the directory link count is left with an inaccurate value unless they are linked by some other directory. 

If unlink() is used on a directory that is empty (contains only the files .  and ..), the directory is unlinked, but the parent directory’s link count is left with an inaccurate value. 

In either of the above cases, the file system should be checked using fsck (see fsck(1M)). To avoid these types of problems, use rmdir() instead (see rmdir(2)).

SEE ALSO

rm(1), close(2), link(2), open(2), rmdir(2), privilege(5). 

STANDARDS CONFORMANCE

unlink(): AES, SVID2, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992