This function does not fail when the file name argument ends in a slash
and (without the slash) names a nonexistent file or a file that is not a
directory, on some platforms:
-HP-UX 11.00, Solaris 9, Irix 5.3.
+FreeBSD 7.2, HP-UX 11.00, Solaris 9, Irix 5.3.
@item
On Windows platforms (excluding Cygwin), this function does usually not
recognize the @file{/dev/null} filename.