The one tool I tend to use most often, as a first resort in the widest range of tasks, simply prints out a byte-value histogram, either as a 256-line list or as a nice 8-column x 32-row table, with an optional summary that counts up character categories like "printable ascii", "non-printable ascii", "8-bit", "iso-printable 8-bit", "digits", "whitespace", etc.
Wow. Too bad I can only ++ once.
Any chance there's a CPAN module to do that? If not, you should definitely write it! Moreover, this sounds like a great talk to give at seminar or conference. Or a great article for perl.com or The Perl Review.
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