recovering clobbered aliases file

[Steven M. Haflich]

Perhaps a more useful way for protecting files which are edited by
a large population is to make safety copies every day, week, and month,
with the obvious crontab entries:

0 1 * * * cd /usr/lib; cp aliases aliases.daily; chmod 444 aliases.daily
0 2 * * 1 cd /usr/lib; cp aliases aliases.weekly; chmod 444 aliases.weekly
0 3 1 * * cd /usr/lib; cp aliases aliases.monthly; chmod 444 aliases.monthly

To avoid clutter in crontab, such daily, weekly, and monthly commands can
be collected into single shell scripts executed by cron.

This is useful for /etc/passwd, /usr/lib/aliases, and perhaps /etc/motd.
It uses little disk space, and provides a useful checkpointing facility
in conjunction with diff when strange changes are not recognized immediately.

						Steve Haflich