|
UNLINK(2) |
System Calls |
UNLINK(2) |
NAME
unlink, unlinkat - remove directory entry
SYNOPSIS
#include <unistd.h>
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
unlinkat() 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
AT_FDCWD, defined in <
fcntl.h>,
unlinkat() also behaves the same as
unlink(). Otherwise,
path is resolved relative to the directory referenced by the
dirfd argument.
If the
flag argument is set to the value
AT_REMOVEDIR, defined in <
fcntl.h>,
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 references to the file are closed.
If the
path argument is a directory and the filesystem supports
unlink() and
unlinkat() on directories the behaviour is dependent on the filesystem.
If the
path argument is a directory and the filesystem does not support
unlink() and
unlink() on directories (for example, ZFS), the call will fail with
errno set to
EPERM.
Upon successful completion,
unlink() and
unlinkat() will mark for update the
st_ctime and
st_mtime fields of the parent directory. If the file's link count is not 0, the
st_ctime 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.
ERRORS
The
unlink() and
unlinkat() functions will fail if:
EACCES
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.
EACCES
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 characters and the file system accepts only file names where all characters are part of the UTF-8 character codeset.
EINTR
A signal was caught during the execution of the unlink() function.
ELOOP
Too many symbolic links were encountered in translating path.
ENAMETOOLONG
The length of the path argument exceeds PATH_MAX, or the length of a path component exceeds NAME_MAX while _POSIX_NO_TRUNC 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 descriptor for unlinkat() is not AT_FDCWD or does not reference a directory.
EPERM
The named file is a directory and {PRIV_SYS_LINKDIR} 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:
ENAMETOOLONG
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds { PATH_MAX}.
ETXTBSY
The entry to be unlinked is the last directory entry to a pure procedure (shared text) file that is being executed.
USAGE
Applications should use rmdir(2) to remove a directory.
ATTRIBUTES
See
attributes(5) for descriptions of the following attributes:
|
ATTRIBUTE TYPE |
ATTRIBUTE VALUE |
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|
|
Interface Stability |
unlink() is Standard; unlinkat() is Evolving |
|
|
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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)