awk
gawk - pattern scanning and processing language
Command manuals for editor
emacs
emacs - GNU project Emacs editor
groff
groff - front end to the GNU roff document formatting system
nano
nano - Nano's ANOther text editor, inspired by Pico
patch
patch - apply a diff file to an original
sed
sed - stream editor for filtering and transforming text
vim
vim - Vi IMproved, a programmer's text editor