Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!charyb!dan
From: dan@charyb.COM (Dan Mick)
Newsgroups: comp.unix.questions
Subject: Re: crontab update
Keywords: crontab,question,update table,update crontab file
Message-ID: <374@charyb.COM>
Date: 24 Feb 90 01:32:45 GMT
References: <855@edstip.EDS.COM>
Reply-To: dan@charyb.UUCP (Dan Mick)
Distribution: na
Organization: KFW Corporation, Newbury Park, CA
Lines: 29

In article <855@edstip.EDS.COM> ohrnb@edstip.EDS.COM (Erik Ohrnberger) writes:

>I have a question about the safest way to update the cron program's
>crontab file.  What I currently do is update the crontab file, and then
>rebot the system, to make sure that cron program reads the updated contab
>file.  Is all this required?  Does the cron program re-read the crontab
>file everytime that it wakes up?  Is there a special procedure to correctly
>update the crontab file?

RTFM.  From the SunOS manual on cron:


     Cron examines /usr/lib/crontab under  the  following  condi-
     tions:

     o  At least once per hour (on the hour).

     o  When the next command is to be run  -  cron  looks  ahead
        until the next command and sleeps until then.

     o  When cron's process is sent a  SIGHUP.  This  means  that
        someone who changes /usr/lib/crontab can get cron to look
        at it right away.

So update crontab and do "ps ax | grep cron" to get cron's pid, then
"kill -HUP <pid>".

Of course, this isn't guaranteed to work except on SunOS 3.2; read your
man pages to be sure.