The "-p" option (also described in perlrun) might be useful as well. The choice between "-p" and "-n" is whether you want to print every line of data after your perl script is applied to it, or whether you want to leave some (or all) lines of text unprinted (e.g. to do something else instead after all the input has been read and processed).

In the latter case, you'll also want to learn about using the END{...} block -- e.g.:

# one-liner to report histogram of byte values from data:

cat some.data.* | perl -ne '$h{$_}++for(split//);END{printf"%x %d\n",o
+rd(),$h{$_}for(sort keys %h)}'
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