Cron Problems

eagle683 · 07-26-2005, 02:30 PM

Does anyone see what I am doing wrong?

The following is a crontab, and it is not working every 5 minutes as it should.

The path is correct.

0,5,10,15,20,25,30,35,40,45,50,55 * * * * /path/to/where/my/directory/code/perl program.pl testfile.txt

stefanlasiewski · 07-26-2005, 02:57 PM

If this is Linux, look to see if there are corresponding entries in /var/log/cron (You probably need to be root to see that file). That logfile may be in a different location on other Unixes.

eagle683 · 07-26-2005, 03:05 PM

It is a unix machine, and if I use the crontab -l - I see my file listed.

stefanlasiewski · 07-26-2005, 03:26 PM

Right, but 'crontab -l' only lists your cron table.

/var/log/cron is the cron logfile, and will often tell you if a cronjob actually did run every 5 minutes or not. It is a good place to start.

In addition, you should probably capture the standard output & standard error to a logfile, like this:

Code:

# Executes once every 5 minutes
0,5,10,15,20,25,30,35,40,45,50,55 * * * * date >/tmp/date.log 2>&1
# Executes 6 minutes past the hour
6 * * * * foo >/tmp/foo.log 2>&1

Here is the output in /var/log/cron , which shows that the cronjobs were executed:

Code:

% tail /var/log/cron
Jul 26 13:15:00 devel01 CROND[21951]: (stefanl) CMD (date)
Jul 26 13:19:00 devel01 CROND[21974]: (stefanl) CMD (foo)

The output from the cron commands themselves are in the /tmp/*.log files that I created above:

Code:

% cat /tmp/date.log
Tue Jul 26 13:25:00 PDT 2005

% cat /tmp/foo.log
/bin/sh: line 1: foo: command not found

If you don't do this, then any output from 'perl program.pl testfile.txt' will be sent to you via mail, but if mail is not setup correctly the output will sit in the mail queue forever.

eagle683 · 07-26-2005, 03:38 PM

ok, I understand, and that could be the problem. It is on a school server, and mail is not set up.

So, this is most likely the cause of the problem?

stefanlasiewski · 07-26-2005, 04:48 PM

There's a problem with either cron or your script. You need to see both the cron output and the script output to debug this problem.

I suggest printing the standard output & standard error to a logfile, in /tmp or under your home directory with a command like 'perl yourscript.pl textfile.txt > $HOME/yourscript.log 2>&1

Then you can look for errors in in $HOME/yourscript.log . You will probably find the error in $HOME/yourscript.log .

keefaz · 07-26-2005, 06:26 PM

Maybe you could replace :

Code:

# Executes once every 5 minutes
0,5,10,15,20,25,30,35,40,45,50,55 * * * * date >/tmp/date.log 2>&1

With :

Code:

# Executes once every 5 minutes
*/5 * * * * date >/tmp/date.log 2>&1