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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 *pathname);
#include <fcntl.h> /* Definition of AT_* constants */
#include <unistd.h>
int unlinkat(int dirfd, const char *pathname, 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 the pathname given in pathname 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 the pathname given in pathname is relative and dirfd is the
special value AT_FDCWD, then pathname is interpreted relative to
the current working directory of the calling process (like
unlink() and rmdir(2)).
If the pathname given in pathname 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 pathname. If the AT_REMOVEDIR flag is specified, it
performs the equivalent of rmdir(2) on pathname.
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 pathname is not
allowed for the process's effective UID, or one of the
directories in pathname did not allow search permission.
(See also path_resolution(7).)
EBUSY The file pathname 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 pathname points outside your accessible address space.
EIO An I/O error occurred.
EISDIR pathname 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
pathname.
ENAMETOOLONG
pathname was too long.
ENOENT A component in pathname does not exist or is a dangling
symbolic link, or pathname is empty.
ENOMEM Insufficient kernel memory was available.
ENOTDIR
A component used as a directory in pathname 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 pathname 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 pathname 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 pathname is relative but dirfd is neither AT_FDCWD nor a
valid file descriptor.
EINVAL An invalid flag value was specified in flags.
EISDIR pathname refers to a directory, and AT_REMOVEDIR was not
specified in flags.
ENOTDIR
pathname 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 pathname is a relative pathname, 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-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. 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
[email protected]
Linux man-pages 6.9.1 2024-06-13 unlink(2)
Pages that refer to this page: rm(1), unlink(1), chmod(2), close(2), fcntl(2), 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 2024-06-26 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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