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unlink, unlinkat - remove directory entry

#include <unistd.h>

int unlink(const char *path);

int unlinkat(int dirfd, const char *path, int flag);

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 directory is unlinked from its parent with no cleanup being performed. In UFS, the disconnected directory will be found the next 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 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.

Upon successful completion, 0 is returned. Otherwise, -1 is returned, errno is set to indicate the error, and the file is not unlinked.

The unlink() and unlinkat() functions will fail if: EACCES

EACCES EBUSY EFAULT EILSEQ EINTR ELOOP ENAMETOOLONG ENOENT ENOLINK ENOTDIR EPERM EROFS

The unlink() and unlinkat() functions may fail if: ENAMETOOLONG

ETXTBSY

Applications should use rmdir(2) to remove a directory.

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

Interface Stability

unlink() is Standard; unlinkat() is Evolving

MT-Level Async-Signal-Safe

rm(1), close(2), link(2), open(2), rmdir(2), remove(3C), attributes(5), privileges(5), fsattr(5)