NAME
unlink
, unlinkat
— remove directory
entry
SYNOPSIS
#include
<unistd.h>
int
unlink
(const char *path);
int
unlinkat
(int
fd, const char
*path, int
flag);
DESCRIPTION
The
unlink
()
function removes the link named by path from its
directory and decrements the link count of the file which was referenced by
the link. If that decrement reduces the link count of the file to zero, and
no process has the file open, then all resources associated with the file
are reclaimed. If one or more process have the file open when the last link
is removed, the link is removed, but the removal of the file is delayed
until all references to it have been closed.
The
unlinkat
()
system call is equivalent to unlink
() or
rmdir
()
except in the case where path specifies a relative
path. In this case the directory entry to be removed is determined relative
to the directory associated with the file descriptor
fd instead of the current working directory.
The values for flag are constructed by a
bitwise-inclusive OR of flags from the following list, defined in
<fcntl.h>
:
AT_REMOVEDIR
- Remove the directory entry specified by fd and path as a directory, not a normal file.
If
unlinkat
()
is passed the special value AT_FDCWD
in the
fd parameter, the current working directory is used
and the behavior is identical to a call to unlink or
rmdir respectively, depending on whether or not the
AT_REMOVEDIR
bit is set in flag.
RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.
ERRORS
The unlink
() system call will fail if:
- [
EACCES
] - Search permission is denied for a component of the path prefix.
- [
EACCES
] - Write permission is denied on the directory containing the link to be removed.
- [
EBUSY
] - The entry to be unlinked is the mount point for a mounted file system.
- [
EBUSY
] - The file named by the path argument cannot be unlinked because it is being used by the system or by another process.
- [
EFAULT
] - Path points outside the process's allocated address space.
- [
EIO
] - An I/O error occurs while deleting the directory entry or deallocating the inode.
- [
ELOOP
] - Too many symbolic links are encountered in translating the pathname. This is taken to be indicative of a looping symbolic link.
- [
ENAMETOOLONG
] - A component of a pathname exceeds
{NAME_MAX}
characters, or an entire path name exceeds{PATH_MAX}
characters (possibly as a result of expanding a symlink). - [
ENOENT
] - The named file does not exist.
- [
ENOTDIR
] - A component of the path prefix is not a directory.
- [
EPERM
] - The named file is a directory and the effective user ID of the process is not the super-user.
- [
EPERM
] - The directory containing the file is marked sticky, and neither the containing directory nor the file to be removed are owned by the effective user ID.
- [
EROFS
] - The named file resides on a read-only file system.
In addition to the errors returned by the
unlink
(), the unlinkat
() may
fail if:
- [
EBADF
] - The path argument does not specify an absolute path
and the fd argument is neither
AT_FDCWD
nor a valid file descriptor open for searching. - [
ENOTEMPTY
] - The flag parameter has the
AT_REMOVEDIR
bit set and the path argument names a directory that is not an empty directory, or there are hard links to the directory other than dot or a single entry in dot-dot. - [
ENOTDIR
] - The flag parameter has the
AT_REMOVEDIR
bit set and path does not name a directory. - [
EINVAL
] - The value of the flag argument is not valid.
- [
ENOTDIR
] - The path argument is not an absolute path and
fd is neither
AT_FDCWD
nor a file descriptor associated with a directory.
SEE ALSO
STANDARDS
The unlinkat
() system call is expected to
conform to POSIX.1-2008 .
HISTORY
An unlink
() function call appeared in
Version 6 AT&T UNIX. The
unlinkat
() system call appeared in OS X 10.10