If not already set, sets the default editor. Falls back to vi(1),
if vim(1) is not available.
+: **LESS_TERMCAP_***
+Some environment variables that add colour support to less(1) for viewing
+man pages. See termcap(5) for details.
+
: **MAIL**
The mailbox file for the current user is set to /var/mail/$USER, if not
already set otherwise.