Apart from the dubious educational value of one-liners, I don't like this collection at all, for two reasons:

• It encourages cargo cult programming
• A great deal of these exampels could be made much easier using a database instead of plain text files. Even a minimalist database such as SQLite would greatly simplify tasks such as "Calculate sum of the nth column of tabular data" or "Calculate sum of a set of columns for each row". I mean, if you need to sum up some values, you need to read all the text anyway, so while you are reading it, it makes sense to export the data into a database, and then get the stats in no time.

Since they are ready-to-use recipes, it would have been more useful to save each case into a well written Perl script, with properly named variables, and using a database when needed.

The way it is now, it will just spread the rumor of Perl being a write-only language.