Question

I can’t seem to run a simple bash file as a cron job that runs once a minute.

#!/bin/bash 

NET_INTERFACE=eth0

CURRENT_IP=`/sbin/ifconfig $NET_INTERFACE | sed -n "/inet addr:.*255.255.25[0-5].[0-9]/{s/.*inet addr://; s/ .*//; p}"`

wget -q --delete-after "http://abc.co.uk/raspiUpdate.php?pi=1&ip=${CURRENT_IP}"

In the crontab I have:

 *     *     *     *     *        /home/user/Scripts/script.sh

Where am I going wrong?

Thanks

Answer 1

To troubleshoot this cron issue a few steps come to mind:

1. double-check the scripts file name you put in your crontab:

   $ ls -lah  /home/user/Scripts/script.sh
   $ cat /home/user/Scripts/script.sh
   

2. check that that script is executable by the user the crontab is installed for. i.e. if you use /etc/crontab, it should be executable by root, if you used

   $ crontab -e
   

   it should be executable by your userid.

   Actually running that script should already give you a hint.

3. look for hints provided by cron. Depending on what distribution you run, the file cron logs to is different. For debian it should be /var/log/syslog IIRC

If you can’t find an error message anywhere, it’s hard to tell what’s wrong. Generally if I reach that point, I stop and go to sleep or do something else.

[edit]
And when I return, i often find the error. 🙂

p.s.:

4. i recently had problems with dots in the filename. Some cron implementations ignore files in /etc/cron.* with dots in their filename. Documented here: http://manpages.ubuntu.com/manpages/xenial/en/man8/cron.8.html as Debian specific. But I think I had this issue also on Fedora.