The best way to validate your regex is to read the docs re regexen; perlre, perlretut, etc (and there's lots of etc inside perldoc, too) and use the knowledge acquired to refine your ability to understand the regex.

Second best, perhaps? Seek out a regex explanation utility of the sort frequently mentioned here.

Next best, try it. Test (brute force) a substantial subset or all the commands you're likely to use, in a dry run setting like:

#pseudocode
my @commands=qw(ls rm rd cat....);

for $command(@commands) {
    if ($command =~ /(your regex here)/ ) {
        say "regex matched $command";
    } else {
         say "Oops! $command slipped by";
    }
}
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