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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | BUGS | SEE ALSO | COLOPHON |
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unlink(2) System Calls Manual unlink(2)
unlink, unlinkat - delete a name and possibly the file it refers
to
Standard C library (libc, -lc)
#include <unistd.h>
int unlink(const char *path);
#include <fcntl.h> /* Definition of AT_* constants */
#include <unistd.h>
int unlinkat(int dirfd, const char *path, int flags);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
unlinkat():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_ATFILE_SOURCE
unlink() deletes a name from the filesystem. If that name was the
last link to a file and no processes have the file open, the file
is deleted and the space it was using is made available for reuse.
If the name was the last link to a file but any processes still
have the file open, the file will remain in existence until the
last file descriptor referring to it is closed.
If the name referred to a symbolic link, the link is removed.
If the name referred to a socket, FIFO, or device, the name for it
is removed but processes which have the object open may continue
to use it.
unlinkat()
The unlinkat() system call operates in exactly the same way as
either unlink() or rmdir(2) (depending on whether or not flags
includes the AT_REMOVEDIR flag) except for the differences
described here.
If path is relative, then it is interpreted relative to the
directory referred to by the file descriptor dirfd (rather than
relative to the current working directory of the calling process,
as is done by unlink() and rmdir(2) for a relative pathname).
If path is relative and dirfd is the special value AT_FDCWD, then
path is interpreted relative to the current working directory of
the calling process (like unlink() and rmdir(2)).
If path is absolute, then dirfd is ignored.
flags is a bit mask that can either be specified as 0, or by ORing
together flag values that control the operation of unlinkat().
Currently, only one such flag is defined:
AT_REMOVEDIR
By default, unlinkat() performs the equivalent of unlink()
on path. If the AT_REMOVEDIR flag is specified, it
performs the equivalent of rmdir(2) on path.
See openat(2) for an explanation of the need for unlinkat().
On success, zero is returned. On error, -1 is returned, and errno
is set to indicate the error.
EACCES Write access to the directory containing path is not
allowed for the process's effective UID, or one of the
directories in path did not allow search permission. (See
also path_resolution(7).)
EBUSY path cannot be unlinked because it is being used by the
system or another process; for example, it is a mount point
or the NFS client software created it to represent an
active but otherwise nameless inode ("NFS silly renamed").
EFAULT path points outside your accessible address space.
EIO An I/O error occurred.
EISDIR path refers to a directory. (This is the non-POSIX value
returned since Linux 2.1.132.)
ELOOP Too many symbolic links were encountered in translating
path.
ENAMETOOLONG
path was too long.
ENOENT A component in path does not exist or is a dangling
symbolic link, or path is empty.
ENOMEM Insufficient kernel memory was available.
ENOTDIR
A component used as a directory in path is not, in fact, a
directory.
EPERM The system does not allow unlinking of directories, or
unlinking of directories requires privileges that the
calling process doesn't have. (This is the POSIX
prescribed error return; as noted above, Linux returns
EISDIR for this case.)
EPERM (Linux only)
The filesystem does not allow unlinking of files.
EPERM or EACCES
The directory containing path has the sticky bit (S_ISVTX)
set and the process's effective UID is neither the UID of
the file to be deleted nor that of the directory containing
it, and the process is not privileged (Linux: does not have
the CAP_FOWNER capability).
EPERM The file to be unlinked is marked immutable or append-only.
(See FS_IOC_SETFLAGS(2const).)
EROFS path refers to a file on a read-only filesystem.
The same errors that occur for unlink() and rmdir(2) can also
occur for unlinkat(). The following additional errors can occur
for unlinkat():
EBADF path is relative but dirfd is neither AT_FDCWD nor a valid
file descriptor.
EINVAL An invalid flag value was specified in flags.
EISDIR path refers to a directory, and AT_REMOVEDIR was not
specified in flags.
ENOTDIR
path is relative and dirfd is a file descriptor referring
to a file other than a directory.
POSIX.1-2008.
unlink()
SVr4, 4.3BSD, POSIX.1-2001.
unlinkat()
POSIX.1-2008. Linux 2.6.16, glibc 2.4.
glibc
On older kernels where unlinkat() is unavailable, the glibc
wrapper function falls back to the use of unlink() or rmdir(2).
When path is relative, glibc constructs a pathname based on the
symbolic link in /proc/self/fd that corresponds to the dirfd
argument.
Infelicities in the protocol underlying NFS can cause the
unexpected disappearance of files which are still being used.
rm(1), unlink(1), chmod(2), link(2), mknod(2), open(2), rename(2),
rmdir(2), mkfifo(3), remove(3), path_resolution(7), symlink(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.15 2025-05-17 unlink(2)
Pages that refer to this page: pmlock(1), rm(1), unlink(1), chmod(2), close(2), F_NOTIFY(2const), io_uring_enter2(2), io_uring_enter(2), link(2), mkdir(2), mknod(2), open(2), rename(2), rmdir(2), symlink(2), syscalls(2), getcwd(3), io_uring_prep_unlink(3), io_uring_prep_unlinkat(3), remove(3), shm_open(3), inotify(7), signal-safety(7), symlink(7), unix(7), lsof(8), mount(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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