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unlink(2)                   BSD System Calls Manual                  unlink(2)


     unlink, unlinkat -- remove directory entry


     #include <unistd.h>

     unlink(const char *path);

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


     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 direc-
     tory entry to be removed is determined relative to the directory associ-
     ated with the file descriptor fd instead of the current working direc-

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

             Remove the directory entry specified by fd and path as a direc-
             tory, not a normal file.

     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.


     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() 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

     [EFAULT]           Path points outside the process's allocated address

     [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} charac-
                        ters, or an entire path name exceeds {PATH_MAX} char-
                        acters (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 direc-
                        tory 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.


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


     The unlinkat() system call is expected to conform to POSIX.1-2008 .


     An unlink() function call appeared in Version 6 AT&T UNIX.  The
     unlinkat() system call appeared in OS X 10.10

4th Berkeley Distribution        June 4, 1993        4th Berkeley Distribution

OS X 10.10 - Generated Thu Oct 30 20:39:11 CDT 2014
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