An interesting tool that has been developed since 1991 (which is roughly around the time the WWW and Linux was born, whew). Kudos to the author for the dedication and consistency.
Since nowadays SQL is pretty much ubiquitous, users might also want to check out an alternative tool, App::fsql. For example (taking a similar example from the module's doc), to select entries in /etc/passwd where UID is between 1000 and 2000:
$ ( echo -e "login\tpassword\tuid\tgid\tgecos\thome\tshell"; sed 's/:/\t/g' /etc/passwd ) | fsql --add-tsv - 'SELECT * FROM stdin WHERE uid >= 1000 AND uid <= 2000' --format text --aoh