--- name: "unlink" section: "2" platform: "macos" package: "xnu" version: "12377.121.6" release: "macOS 26.5" platforms: ["linux", "freebsd", "macos"] url: "https://new.carta.tech/unlink/2" --- # unlink(2) remove directory entry ## NAME **unlink**, **unlinkat** – remove directory entry ## SYNOPSIS **#include \** *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. - AT\_SYMLINK\_NOFOLLOW\_ANY If *path* contains a symbolic link in any intermediate directory of the path, it is not followed and an error is returned instead. - AT\_RESOLVE\_BENEATH If *path* does not reside in the hierarchy beneath the starting directory, an error is returned. - AT\_NODELETEBUSY If *path* refers to a file with any open file descriptors, an error is returned. - AT\_UNIQUE If *path* resolves to a vnode with multiple hard links, an error is returned. 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. - \[EBUSY\] The flag parameter has the AT\_NODELETEBUSY bit set and the file referred to by *path* has one or more open file descriptors. - \[EFAULT\] *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. - \[ELOOP\] The *flag* parameter has the AT\_SYMLINK\_NOFOLLOW\_ANY bit set and one of the intermediate directories in the *path* argument is a symbolic link. - \[ENOTCAPABLE\] The flag parameter has the AT\_RESOLVE\_BENEATH bit set and *path* does not reside in the directory hierarchy beneath the starting directory. - \[ENOTCAPABLE\] The flag parameter has the AT\_UNIQUE bit set and *path* resolves to a vnode with multiple links. ## SEE ALSO [close(2)](/close/2.md), [link(2)](/link/2.md), [rmdir(2)](/rmdir/2.md), [symlink(7)](/symlink/7.md) ## 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