The regular expression is generated in the notation used by awk, ed, egrep, Emacs, expect, find, grep, lex, Lisp, MySQL, OpenOffice.org, Perl, PHP, PostgreSQL, Procmail, Python, Sed, Tcl, VBscript, Vi, and Vim.
agrep (approximate grep) is a proprietary approximate string matching program, developed by Udi Manber and Sun Wu between 1988 and 1991, for use with the Unix operating system.
:advent, ar, arc, at, cal, cat, chess (gnu), cmp, comm, compress, conquest, cron, dd, diff, ed, eroff, grep, head, indent, make, MicroEMACS, more, nroff, roff, sc, sed, sort, split, STEVIE, strings, sum, tail, tar, tee, ularn, uniq, vi, wanderer, wc, xmodem, ymodem, zmodem, zoo