Forcing SVR3 cron to re-read crontabs

[Lyndon Nerenberg]

[ This has nothing to do with mail anymore - followups in comp.unix.questions ]

In article <483 at sequoia.UUCP> dewey at sequoia.UUCP (Dewey Henize) writes:
>In article <1524 at auspex.auspex.com> guy at auspex.auspex.com (Guy Harris) writes:
>>The S5R3 "cron" and, I think, the S5R2 "cron", do not check any of the
>>"crontab" files unless they're told to;
>
>Can someone who's looking at source or speaking from experience tell me, please,
>HOW they're told to?  Is there a signal that could be used?  It would seem the
>most 'unixy' thing, but I've not found it in any of our docs, and we don't have
>any source...

The SVR3 cron communicates with the crontab command via a named pipe
(/usr/lib/cron/FIFO) that's created when cron starts up. You would
have to fake the messages being written on the pipe to get cron to do
its internal updates, which means re-inventing crontab(1), so why bother?

Unfortunately, cron no longer pays attention to signals (other than
SIGTERM) so kill -1 no longer does anything. You could write a script
to pull cron's PID out of a ps listing, send it a SIGTERM, then restart
cron. Or you could just use crontab(1) ... :-)

-- 
Lyndon Nerenberg   Computing Services   Athabasca University
{alberta,attvcr,ncc}!atha!lyndon  ||  lyndon at nexus.ca