Learning the vi Editor by Linda Lamb; O'Reilly & Associates; ISBN 0-937175-67-6; 1992. A complete introduction to vi, structured like UNIX in a Nutshell.
Learning GNU Emacs, second edition, by Deb Cameron & Bill Rosenblatt; O'Reilly & Associates; ISBN 1-56592-152-6; 1996. Emacs doesn't come with some versions of UNIX, but users find and install it - especially the version called GNU Emacs.
Learning Perl, second edition, by Randal L. Schwartz and Tom Christiansen; O'Reilly & Associates; ISBN 1-56592-284-0; 1997. An introduction to one of the most popular and powerful ways to process text and data and use all the power in your computer system.