Unlink removes the entry for the file path from its directory. If this entry was the last link to the file, and no process has the file
open, then all resources associated with the file are reclaimed. If, however, the file was open in any process, the actual resource recla-
mation is delayed until it is closed, even though the directory entry has disappeared.
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.
The unlink succeeds unless:
[ENOTDIR] A component of the path prefix is not a directory.
[EINVAL] The pathname contains a character with the high-order bit set.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[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.
[ELOOP] Too many symbolic links were encountered in translating the pathname.
[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.
[EBUSY] The entry to be unlinked is the mount point for a mounted file system.
[EIO] An I/O error occurred while deleting the directory entry or deallocating the inode.
[EROFS] The named file resides on a read-only file system.
[EFAULT] Path points outside the process's allocated address space.