UNEXPAND (man1p)
unexpand — convert spaces to tabs
unexpand — convert spaces to tabs
rmdel — remove a delta from an SCCS file (DEVELOPMENT)
bg — run jobs in the background
vi — screen-oriented (visual) display editor
tail — copy the last part of a file
pwd — return working directory name
cd — change the working directory
readonly — set the readonly attribute for variables
at — execute commands at a later time
colon — null utility