unlink(2)unlink(2)NAMEunlink - Remove a directory entry
SYNOPSIS
#include <unistd.h>
int unlink(
const char *path );
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
unlink(): XSH4.0, XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the directory entry to be removed.
DESCRIPTION
When the directory entry is a hard link, the unlink() function removes
it and decrements the link count of the file referenced by the link.
When the directory entry is a symbolic link, the unlink() function
removes the symbolic link and does not affect any file or directory
named by the contents of the symbolic link.
When all links to a file are removed and no process has the file open
or mapped, all resources associated with the file are reclaimed, and
the file is no longer accessible. If one or more processes have the
file open or mapped when the last link is removed, the link is removed
before the unlink() function returns, but the removal of the file con‐
tents is postponed until all open or map references to the file are
removed.
A hard link to a directory cannot be unlinked.
A process must have write access to the parent directory of the file to
be unlinked with respect to all access policies.
Upon successful completion, the unlink() function marks for update the
st_ctime and st_mtime fields of the directory which contained the link.
If the file's link count is not 0 (zero), the st_ctime field of the
file is also marked for update.
System V Compatibility
[Tru64 UNIX] Any attempt to unlink non-empty directories in the System
V habitat will cause the unlink() call to fail and set errno to
[ENOTEMPTY], even if the process has superuser privileges. This error
behavior is provided in the System V habitat to comply with the SVID-2
specification.
RETURN VALUES
Upon successful completion, a value of 0 (zero) is returned. If the
unlink() function fails, a value of -1 is returned, the named file is
not changed, and errno is set to indicate the error.
ERRORS
If the unlink() function fails, the named file is not unlinked and
errno may be set to one of the following values: One of the following
conditions was encountered: Search permission is denied for a component
of the path prefix, or write permission is denied on the directory con‐
taining the link to be removed. The S_ISVTX option is set on the
directory containing the file referred to by the path argument and the
caller is not the file owner, nor is the caller the directory owner,
nor does the caller have appropriate privileges. One of the following
conditions was encountered: The entry to be unlinked is the mount point
for a mounted file system. The file named by path is a named STREAM.
[Tru64 UNIX] The path parameter is an invalid address. Too many sym‐
bolic links were encountered in translating path. The length of the
path parameter exceeds PATH_MAX or a pathname component is longer than
NAME_MAX; or, pathname resolution of a symbolic link produced an
intermediate result whose length exceeds PATH_MAX. The named file does
not exist or the path parameter points to an empty string. A component
of the path prefix is not a directory. One of the following conditions
was encountered: The named file is a directory. The S_ISVTX option is
set on the directory containing the file referred to by the path argu‐
ment and the caller is not the file owner, nor is the caller the direc‐
tory owner, nor does the caller have appropriate privileges. The entry
to be unlinked is part of a read-only file system. The entry to be
unlinked is the last directory entry to a pure procedure (shared text)
file that is being executed.
[Tru64 UNIX] For NFS file access, if the link() function fails, errno
may also be set to one of the following values: Indicates either that
the request was for a write access to a file but the specified filename
was actually a directory, or that the function was trying to rename a
directory as a file. Indicates either that the system file table is
full, or that there are too many files currently open in the system.
Indicates a stale NFS file handle. A client cannot delete a link
because the server has unmounted or unexported the remote directory; or
the directory that contains an file was either unmounted or unexported
by the server.
SEE ALSO
Commands: link(1), rm(1), unlink(1)
Functions: close(2), link(2), open(2), rmdir(2)
Standards: standards(5)unlink(2)
