If not, why not? What do you use instead?
I find not is usually the cleanest and most readable operator for all sorts of tests.

die "$usage" if not @ARGV;

if (not -r $file) { die "Cannot read $file\n"; }

print "$pattern not found in $file\n" if not $found;
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Regards,
Helgi Briem
helgi AT decode DOT is