unlink
======

POSIX specification:
 http://www.opengroup.org/onlinepubs/9699919799/functions/unlink.html

Gnulib module: unlink

Portability problems fixed by Gnulib:

  * Some systems mistakenly succeed on unlink("link-to-file/"): GNU/Hurd, FreeBSD 7.2, AIX 7.1, Solaris 9.

  * On Mac OS X 10.5.6, in a writable HFS mount, unlink("..") succeeds without doing anything.

Portability problems not fixed by Gnulib:

  * Some systems allow a superuser to unlink directories, even though this can cause file system corruption.  The error given if a process is not permitted to unlink directories varies across implementations; it is not always the POSIX value of EPERM.  Meanwhile, if a process has the ability to unlink directories, POSIX requires that unlink("symlink-to-dir/") remove dir and leave symlink-to-dir dangling; this behavior is counter-intuitive. The gnulib module unlinkdir can help determine whether code must be cautious of unlinking directories.

  * Removing an open file is non-portable: On Unix this allows the programs that have the file already open to continue working with it; the file's storage is only freed when the no process has the file open any more.  On Windows, the attempt to remove an open file fails.