Crontab not launching script

I'm trying to run the following script through crontab every day at 12 :

mount -t nfs /mnt/NAS_DFG
echo >> ~/Documents/Crontab_logs/logs.txt
date >> ~/Documents/Crontab_logs/logs.txt
rsync -ar /home /mnt/NAS_DFG/ >> ~/Documents/Crontab_logs/logs.txt 2>&1
unmout /mnt/NAS_DFG

As it needs to run in sudo, I added the following line to 'sudo crontab' such that I have :

someone@something:~$ sudo crontab -l
# Edit this file to introduce tasks to be run by cron.
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').# 
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
# For more information see the manual pages of crontab(5) and cron(8)
# m h  dom mon dow   command

0 12 * * * ~/Documents/Crontab_logs/ 

But it does not run. I mention that just executing the script thourgh :

sudo ~/Documents/Crontab_logs/

works well, except that no output of the rsync command is written in the log file.

Any ideas what's going wrong ? I think I checked the main source of mistakes, i.e. using shell, leaving an empty line at the end, etc ...

1 answer

  • answered 2018-10-23 13:34 tripleee

    sudo crontab creates a job which runs out of the crontab of root (if you manage to configure it correctly; the syntax in root crontabs is different). When cron runs the job, $HOME (and ~ if you use a shell or scripting language with tilde expansion) will refer to the home of root etc.

    You should probably simply add

    0 12 * * * sudo ./Documents/Crontab_logs/

    to your own crontab instead.

    Notice that crontab does not have tilde expansion at all (but we can rely on the fact that cron will always run out of your home directory).

    ... Though this will still have issues, because if the script runs under sudo and it creates new files, those files will be owned by root, and cannot be changed by your regular user account. A better solution still is to only run the actual mount and umount commands with sudo, and minimize the amount of code which runs on the privileged account, i.e. remove the sudo from your crontab and instead add it within the script to the individual commands which require it.