System Calls unlink(2)
NAME
unlink, unlinkat - remove directory entry
SYNOPSIS
#include
int unlink(const char *path);
int unlinkat(int dirfd, const char *path, int flag);
DESCRIPTION
The unlink() function removes a link to a file. If path
names a symbolic link, unlink() removes the symbolic link
named by path and does not affect any file or directory
named by the contents of the symbolic link. Otherwise,
unlink() removes the link named by the pathname pointed to
by path and decrements the link count of the file referenced
by the link.
The unlinkat() function also removes a link to a file. See
fsattr(5). If the flag argument is 0, the behavior of unlin-
kat() is the same as unlink() except in the processing of
its path argument. If path is absolute, unlinkat() behaves
the same as unlink() and the dirfd argument is unused. If
path is relative and dirfd has the value ATFDCWD, defined
in , unlinkat() also behaves the same as unlink().
Otherwise, path is resolved relative to the directory refer-
enced by the dirfd argument.
If the flag argument is set to the value ATREMOVEDIR,
defined in , unlinkat() behaves the same as
rmdir(2) except in the processing of the path argument as
described above.
When the file's link count becomes 0 and no process has the
file open, the space occupied by the file will be freed and
the file is no longer accessible. If one or more processes
have the file open when the last link is removed, the link
is removed before unlink() or unlinkat() returns, but the
removal of the file contents is postponed until all refer-
ences to the file are closed.
If the path argument is a directory and the filesystem sup-
ports unlink() and unlinkat() on directories, the directory
is unlinked from its parent with no cleanup being performed.
In UFS, the disconnected directory will be found the next
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System Calls unlink(2)
time the filesystem is checked with fsck(1M). The unlink()
and unlinkat() functions will not fail simply because a
directory is not empty. The user with appropriate privileges
can orphan a non-empty directory without generating an error
message.
If the path argument is a directory and the filesystem does
not support unlink() and unlink() on directories (for exam-
ple, ZFS), the call will fail with errno set to EPERM.
Upon successful completion, unlink() and unlinkat() will
mark for update the stctime and stmtime fields of the
parent directory. If the file's link count is not 0, the
stctime field of the file will be marked for update.
RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is
returned, errno is set to indicate the error, and the file
is not unlinked.
ERORS
The unlink() and unlinkat() functions will fail if:
EACES Search permission is denied for a component
of the path prefix, or write permission is
denied on the directory containing the link
to be removed.
EACES The parent directory has the sticky bit set
and the file is not writable by the user,
the user does not own the parent directory,
the user does not own the file, and the user
is not a privileged user.
EBUSY The entry to be unlinked is the mount point
for a mounted file system.
EFAULT The path argument points to an illegal
address.
EILSEQ The path argument includes non-UTF8 charac-
ters and the file system accepts only file
names where all characters are part of the
UTF-8 character codeset.
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System Calls unlink(2)
EINTR A signal was caught during the execution of
the unlink() function.
ELOP Too many symbolic links were encountered in
translating path.
ENAMETOLONG The length of the path argument exceeds
PATHMAX, or the length of a path component
exceeds NAMEMAX while POSIXNOTRUNC is in
effect.
ENOENT The named file does not exist or is a null
pathname.
ENOLINK The path argument points to a remote machine
and the link to that machine is no longer
active.
ENOTDIR A component of the path prefix is not a
directory or the provided directory descrip-
tor for unlinkat() is not ATFDCWD or does
not reference a directory.
EPERM The named file is a directory and
{PRIVSYSLINKDIR} is not asserted in the
effective set of the calling process, or the
filesystem implementation does not support
unlink() or unlinkat() on directories.
EROFS The directory entry to be unlinked is part
of a read-only file system.
The unlink() and unlinkat() functions may fail if:
ENAMETOLONG Pathname resolution of a symbolic link pro-
duced an intermediate result whose length
exceeds {PATHMAX}.
ETXTBSY The entry to be unlinked is the last direc-
tory entry to a pure procedure (shared text)
file that is being executed.
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System Calls unlink(2)
USAGE
Applications should use rmdir(2) to remove a directory.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Interface Stability unlink() is Standard;
unlinkat() is Evolving
MT-Level Async-Signal-Safe
SEE ALSO
rm(1), close(2), link(2), open(2), rmdir(2), remove(3C),
attributes(5), privileges(5), fsattr(5)
SunOS 5.11 Last change: 18 May 2007 4
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