UNLINK(2) MidnightBSD System Calls Manual UNLINK(2)


unlink — remove directory entry


Standard C Library (libc, −lc)


#include <unistd.h>


unlink(const char *path);


The unlink() system call 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 path argument may not be a directory.


The unlink() function returns the value 0 if successful; otherwise the value −1 is returned and the global variable errno is set to indicate the error.


The unlink() succeeds unless:


A component of the path prefix is not a directory.


A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.


The named file does not exist.


Search permission is denied for a component of the path prefix.


Write permission is denied on the directory containing the link to be removed.


Too many symbolic links were encountered in translating the pathname.


The named file is a directory.


The named file has its immutable, undeletable or append-only flag set, see the chflags(2) manual page for more information.


The parent directory of the named file has its immutable or append-only flag set.


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.


An I/O error occurred while deleting the directory entry or deallocating the inode.


The named file resides on a read-only file system.


The path argument points outside the process’s allocated address space.


chflags(2), close(2), link(2), rmdir(2), symlink(7)


The unlink() function appeared in Version 6 AT&T UNIX.

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

MidnightBSD 0.3 December 10, 2006 MidnightBSD 0.3