Perl Programming/Keywords/-W
The -W keyword
edit-W is a file test that tests if the file is writable by effective uid/gid.
It takes one argument, either a FILENAME, a FILEHANDLE, or a DIRHANDLE to test the associated file to see, if something is true about it. If the argument is omitted, it tests $_. -W returns 1 for true and an empty string for false. If the file doesn't exist or can't be examined, it returns undef and sets $! (errno).
Syntax
edit -W FILENAME
-W FILEHANDLE
-W EXPRESSION
-W DIRHANDLE
-W