UNIX for Dummies Questions & Answers

A point. During testing it is not necessary to run the process every minute. It is quite clear that the script is waiting for input which will never come.


What is the contents of the script?


If you run the cron without junking the output (> /dev/null 2>&1) what output is produced in mail for the user of the cron?


The sendmail command above is not correct at all. We can't decode what you intended. What do you want the mail program to do?

What Operating System are you running?

I'm running Ubuntu 9.10 as noted above.

The test_cron program is just a simple test I wrote. Here is the code:

Code:

#! /bin/bash
#

#if ! type promptYesNo > /dev/null 2>&1 ; then . /home/woodnt/scripts/misc.sh ; fi

FILE=/tmp/cron.log
TIME=`date -d now "+%m-%d-%y@%H%M%S"`
if [ ! -f $FILE ] ; then
    touch $FILE
fi

echo "Hello at $TIME" >> $FILE

When I don't send stdout and stderr to the bit bucket. You get the listing I showed at first. Here is is again:

Code:

root     14693  0.0  0.0  91236  1660 ?        S    Feb05   0:00  \_ CRON
root     14694  0.0  0.0  91244  1160 ?        S    Feb05   0:00  |   \_ CRON
woodnt   14696  0.0  0.0  50152  2800 ?        S    Feb05   0:00  |       \_ /usr/sbin/sendmail -i -FCronDaemon -oem woodnt

Hung at the sendmail request. Here, sendmail is a sym-link to postfix which bsd-mailx installs as it's MTA as a dependency.

I unintentionally left the crontab running overnight rather than commenting it out as I meant too, hehe. I'm impatient and I wanted a couple of iterations to see if stopping the mailto would work.

I started this whole thing just to learn about crontabs and to develop a trust of it.

I would prefer its mailing stuff to me, but the send to bit-bucket was just to see if it were (yes, that is proper English as it is conditional clause ) a sendmail issue. It seems it is not.

Don't have this problem running on other 9.10 boxes or a 9.04 box. I'd love to know what is peculiar about this system.

I don't want to reinstall. I'd rather figure it out to learn linux better and also I wanna fix it just on principle of WHY?

Narnie

I get it. When cron itself wants to send mail the cron job hangs with a sendmail command stuck in the process list. The more cron jobs the more stuck jobs.

If you have another system which is working, look for differences. Suggest you approach the Operating System authors about known faults.

Yep, but even when it is not mailing (setting MAILTO=""), it is hanging at a sh job.

I'm really not sure how to go about looking for the differences on this particular issue.

Has me stumped.

Narnie

My advice is to cold install using a definitive rehearsed process which has produced good systems. It is advisible to do a thorough hardware check before loading the Operating System in case this is a duff computer.

Boy I hate to do that if I don't have to because I have done so much to the system.

Now that I'm thinking about it, it seems I had set up ssmtp to do mail from the command line via google (I guess I'm turning into too much of a CL junkie). Then when I noticed I wasn't getting mail from cron and the accumulated, then that is when I uninstalled ssmtp, then installed bsd-mailx+postfix.

I will upgrade to Ubuntu 10.4 LTS in a couple of months, so if this doesn't get figured out then, I'll likely wait to reinstall and just do a temp fix by making a cron job that runs every 30 mins or so to restart the cron service, which I have found will remove all the cron zombie processes.

I'd still like to know why and fix it, but perhaps it is a lost cause.

Narnie

ps, regardless, this has been a great learning processes