unlink.2 (2010 09)

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unlink(2) unlink(2)

NAME

unlink - remove directory entry; delete ﬁle

SYNOPSIS

#include <unistd.h>

int unlink(const char *path);

DESCRIPTION

The unlink() system call 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

unlink() returns the following values:

0 Successful completion.

-1 Failure. errno is set to indicate the error.

ERRORS

unlink() fails, errno is set to one of the following values:

[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.

[EACCES] The process does not have read/write access permission to the parent direc-

tory.

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

[EFAULT] path points outside the process’s allocated address space. The reliable

detection of this error is implementation dependent.

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

[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.

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

path does not exist).

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

[EPERM] The directory containing the ﬁle to be removed has the sticky bit set and

neither the containing directory nor the ﬁle to be removed are owned by the

effective user ID.

[EPERM] The named ﬁle is a directory and the effective user ID is not a user with

appropriate privileges. Some ﬁle systems return this error whenever the

named ﬁle is a directory, regardless of the user ID.

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

[ETXTBSY] The entry to be unlinked is the last link to a pure procedure (shared text)

ﬁle that is being executed.

WARNINGS

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.

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.

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (2 pages)

PAGE 1
unlink(2) unlink(2) NAME unlink - remove directory entry; delete file SYNOPSIS #include int unlink(const char *path); DESCRIPTION The unlink() system call 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.
PAGE 2
unlink(2) unlink(2) 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), remove(3C), privileges(5). STANDARDS CONFORMANCE unlink(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.