|| dieto make it a fatal error if the file test fails. The default is
|| warn. The file test may optionally have a "!' prepended to test for the opposite condition. If you do a cd and then list some relative filenames, you may want to indent them slightly for readability. If you supply your own die() or warn() message, you can use $file to interpolate the filename.
Filetests may be bunched: ``-rwx'' tests for all of
Only the first failed test of the bunch will produce a warning.
The routine returns the number of warnings issued.