man unlink (2): remove directory entry

Other Alias

unlinkat

LIBRARY

Lb libc

SYNOPSIS

In unistd.h Ft int Fn unlink const char *path Ft int Fn unlinkat int fd const char *path int flag

DESCRIPTION

The Fn unlink system call removes the link named by Fa 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 Fa path argument may not be a directory.

The Fn unlinkat system call is equivalent to Fn unlink or Fn rmdir except in the case where Fa 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 Fa fd instead of the current working directory.

The values for Fa flag are constructed by a bitwise-inclusive OR of flags from the following list, defined in In fcntl.h :

AT_REMOVEDIR: Remove the directory entry specified by Fa fd and Fa path as a directory, not a normal file.

If Fn unlinkat is passed the special value AT_FDCWD in the Fa fd parameter, the current working directory is used and the behavior is identical to a call to Fa unlink or Fa rmdir respectively, depending on whether or not the AT_REMOVEDIR bit is set in flag.

RETURN VALUES

Rv -std unlink

ERRORS

The Fn unlink succeeds unless:

Bq Er ENOTDIR: A component of the path prefix is not a directory.
Bq Er EISDIR: The named file is a directory.
Bq Er ENAMETOOLONG: A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
Bq Er ENOENT: The named file does not exist.
Bq Er EACCES: Search permission is denied for a component of the path prefix.
Bq Er EACCES: Write permission is denied on the directory containing the link to be removed.
Bq Er ELOOP: Too many symbolic links were encountered in translating the pathname.
Bq Er EPERM: The named file is a directory.
Bq Er EPERM: The named file has its immutable, undeletable or append-only flag set, see the chflags(2) manual page for more information.
Bq Er EPERM: The parent directory of the named file has its immutable or append-only flag set.
Bq Er 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.
Bq Er EIO: An I/O error occurred while deleting the directory entry or deallocating the inode.
Bq Er EROFS: The named file resides on a read-only file system.
Bq Er EFAULT: The Fa path argument points outside the process's allocated address space.

In addition to the errors returned by the Fn unlink , the Fn unlinkat may fail if:

Bq Er EBADF: The Fa path argument does not specify an absolute path and the Fa fd argument is neither AT_FDCWD nor a valid file descriptor open for searching.
Bq Er ENOTEMPTY: The Fa flag parameter has the AT_REMOVEDIR bit set and the Fa 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.
Bq Er ENOTDIR: The Fa flag parameter has the AT_REMOVEDIR bit set and Fa path does not name a directory.
Bq Er EINVAL: The value of the Fa flag argument is not valid.
Bq Er ENOTDIR: The Fa path argument is not an absolute path and Fa fd is neither AT_FDCWD nor a file descriptor associated with a directory.

STANDARDS

The Fn unlinkat system call follows The Open Group Extended API Set 2 specification.

HISTORY

The Fn unlink function appeared in AT&T System v6 . The Fn unlinkat system call appeared in Fx 8.0 .

The Fn unlink system call traditionally allows the super-user to unlink directories which can damage the file system integrity. This implementation no longer permits it.