I have a sh script. How to run it using crontab?

Question

I have the following file execute-backup-from-container.sh. The content of this file is:

#!/bin/bash
FILE=minime.sql.`date +"%Y%m%d".gz`
CONTAINER='mysql_01'
SCRIPT_ON_CONTAINER='/container-mysql-dump.sh'

${OUTPUT}=$(docker exec ${CONTAINER} /$SCRIPT_ON_CONTAINER)

echo "=============="
echo "$CONTAINER:/$FILE"
echo "=============="
docker cp "$CONTAINER:/$FILE" backup-data/

When I run crontab -e I am putting the following:
0 5 * * 1 /home/me/projects/execute-backup-from-container.sh This means that the execute-backup-from-container.sh should be executed every day at 5:00 am.
The problem is that the script is not executed at all.
So what on earth is the problem? Why is it not executed?

Solution 1

The cron fields corresponding to your entry mean:

minute:       0 
hour:         5 
day of month: * 
month:        * 
day of week:  1 
command:      /home/me/projects/execute-backup-from-container.sh

which translate in English to: Mondays at 5am (any day of the month, any month).

If you want it to be executed:

every day at 5:00 am

then you want that 5th field to be a *:

0 5 * * * /home/me/projects/execute-backup-from-container.sh

Solution 2

Did you check that the file is set to be executable? Here is an example of marking a script as executable:

$ ls -l test.sh
-rw-r--r-- 1 ahill ahill 0 Mar 23 19:30 test.sh
$ chmod +x test.sh
$ ls -l test.sh
-rwxr-xr-x 1 ahill ahill 0 Mar 23 19:30 test.sh

The next thing to check is the environment. cron jobs inherit no environment by default. The "fix" is discussed here:
How can I run a cron command with existing environmental variables?

One of the reasons that the environment is a big deal is that cron might not even find bash! see: https://www.digitalocean.com/community/questions/why-is-cron-not-running-my-sh-script

If you still cannot figure it out, I would do a test: Change your cron job from:

0 5 * * * /home/me/projects/execute-backup-from-container.sh

to:

0 5 * * * /home/me/projects/execute-backup-from-container.sh >> ~/script_errors.log 2>&1 

What will happen: the next time cron launches the job, error messages produced will be dumped into the text file script_errors.log. (change the path to the script_errors.log file to whatever seems appropriate, but make sure the path exists, though the file does not need to.)

I also noticed something in the OP that might be the real problem: the word "container." If the script is inside of a Docker container, then this is likely the solution:
https://www.ekito.fr/people/run-a-cron-job-with-docker/

Comments

[Cristian]

@steeldriver you are right. If I want to make it every day should I have to put * instead of 1?

[Jeff Schaller]

If any of the answers solved your problem, please accept it by clicking the checkmark next to it. Thank you!

[Jeff Schaller]

Also, you have a syntax error in the script: ${OUTPUT}=... should just be OUTPUT=...

[Kusalananda]

This answer misses the point that the schedule used in the crontab is wrong.

[Jeff Schaller]

is there a cron error message in the logs? Is the script executable?

[Cristian]

Good point with the permissions. I had already put 777 to execute-backup-from-container.sh file before posting the question, so it does not help that, but I will check the environment variable solution and let you know.

[Cristian]

No, there are no error messages in the logs. I have read the logs with ` grep CRON /var/log/syslog`

[Cristian]

So I have used the following environment variables but still not working: HOME=/home/cristian LOGNAME=cristian PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/us‌​r/bin SHELL=/bin/bash PWD=/home/cristian BASH_ENV=/home/cristian/.profile

[Art Hill]

I would do a test: Change your cron job from: 0 5 * * * /home/me/projects/execute-backup-from-container.sh to: 0 5 * * * /home/me/projects/execute-backup-from-container.sh >> ~/script_errors.log 2>&1 What will happen: the next time cron launches the job, error messages produced will be dumped into the text file script_errors.log. (change the path to the script_errors.log file to whatever seems appropriate, but make sure the path exists, but he file does not need to.)

[Art Hill]

I noticed something in the OP that might be the problem: The word "container." If the script is INSIDE a docker container, I bet this is the answer: ekito.fr/people/run-a-cron-job-with-docker