How to execute shell script via crontab?

Question

I have a notify.sh script that looks like:

notify-send "hi welcome"

My crontab notification for 2 PM:

0 14 * * * home/hacks/notify.sh

However, this doesn't work. What is the problem?

Answer 1

Your script is missing a #! line at the start, which is the magic interpreted by the kernel to say which command interpreter is to be used for the script.

Make it look like this:

#!/bin/sh
notify-send "hi welcome"

and make sure the script is executable:

ls -l home/hacks/notify.sh
chmod +x home/hacks/notify.sh
ls -l home/hacks/notify.sh

Also, since you're asking for this to happen just once a day, is the timezone of the crontab the same as your own timezone? You might find this happening at 2pm GMT.

Answer 2

4 hypothesis:

• the cron daemon is not running (do a ps axfww | grep cron and check)

• the notify-send is trying to send output to a terminal, or an X session -- but it is ran from within the cron environment and it does not know "who to talk to", so to speak.

• your script is not executable

• the home/ path in the crontab script is relative to the user the scripts gets executed as. Try using the full path

Answer 3

Making crontab running is easy only . Here I am going to say how to run crontab jobs. It is useful for anyone who is stuck on crontab.

*/1 * * * * cd /home/hacks && sh notify.sh

To make the script executable, we have to do:

chmod +x home/hacks/notify.sh

Here i run this script for every one minute ... By doing below script, you can write it in a log file to find whether its working

write log

*/1 * * * * cd /home/hacks && sh notify.sh>>test.log

send mail

*/1 * * * * cd /home/hacks && sh notify.sh>>test.log | mail -s "Hi this is example" user@domain.com

Answer 4

You have to open crontab by the following command:

crontab -u username -e (to edit) -l(to list) -r(to remove) 10(minutes) 8-15(hours) *(Day of month) *(month) 1,3,5(days of week) /path/to/script/script_name.sh

This will run your script once an hour from 8AM-3PM at 10 minutes past the hour every Monday, Wednesday and Friday.

Answer 5

Add export DISPLAY=:0 above the notify-send line in your script. This addresses lornezog's second point.