Scheduling a Python job in Linux

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I’m trying to schedule a python script to run via crontab and it’s not working. This is on Citrix’s XenServer platform which is Linux.

The script runs fine from the command prompt, but when I run it via cron i get an error:

Code:

File "./sshkill.py", line 3
ps -u root -f | grep "ssh grpadmin@192.168.200.20" | while read psline; do
^
SyntaxError: invalid syntax

The script is:

Code:

#!/bin/sh
ps -u root -f | grep "ssh [EMAIL="grpadmin@192.168.200.20"]grpadmin@192.168.200.20[/EMAIL]" | while read psline; do
pid=`echo $psline | awk '{print $2}'`
ppid=`echo $psline | awk '{print $3}'`
if test $ppid -eq '1' ; then
kill $pid
fi
done 

and the crontab entry I have is:

Code:

2 * * * * /usr/bin/python /usr/bin/sshkill.py > /tmp/sshkill.txt 2>&1

Any ideas?

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Replies

Does Cron support redirect ?

cheers, Paul

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What you posted is not a python script, it is a shell script (that is what the “#!/bin/sh” on the first line means). No wonder python doesn’t like it.

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I had pulled the script from a forum posting, and a different post in the thread mentioned something about python, so I assumed…

That being said, I still get the error, even changing the crontab entry to /bin/bash. Other posts in the thread say they’ve gotten it running, so I must be missing something.

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Try this: change the name of the file to sshkill and then change your cron command to:

Code:

2 * * * * /usr/bin/sshkill > /tmp/sshkill.txt 2>&1

Also, make sure that your script is executable. You can do this as follows (signed in as root):

Code:

chmod a+x /usr/bin/sshkill

Then to test the command to make sure it runs, from the command prompt enter:

Code:

sshkill

Only once the command works from the command line can you expect it to run via cron.

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Script runs from command prompt fine. I gave up for a little while and when I came back it had run at 11:02. I was trying to schedule it to run every 2 minutes, but it seems to be running at 2 minutes past the hour?

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You have specified minute 2 of every hour on every day etc. Try this – all minutes with an interval of 2.
0-59/2 * * * *

cheers, Paul

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That’s got it! Thanks all.

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