Running script via crontab on reboot

Question

I am using Ubuntu Server 16.04. Everytime I log in, I need to manually run my script: /home/user/ini.sh. This script calls other scripts that need sudo permissions, so I get the prompt, insert my password and done. Now I want to configure a way to run the script automatically when the system starts.

I have used crontab -eand added the line

@reboot /home/user/ini.sh

This does not seem to work. I have tried different options as suggested by other users in here, here, here or here.

@reboot user    /home/user/ini.sh
@reboot root    /home/user/ini.sh
@reboot sh      /home/user/ini.sh
*/1 * * * *     /home/user/ini.sh
....

adding SHELL=/bin/bash... But I cannot get it to work. I have also tried

@reboot echo "yes" > /home/user/yes.txt

And the file is created - empty though, with no content inside (this demonstrates something is working but I am making a mistake somewhere).

Where is my error?

EDIT

I have also unsuccessfully tried to sudo crontab -e and use

@reboot root    /home/user/ini.sh

Because if you have to run it as root, you need to edit crontab for the root user (sudo crontab -e) — Félicien, Feb 14 '18 at 13:30
Jobs inserted via crontab -e (whether your user or the root user i.e. sudo crontab -e) should NOT include the user field after the time spec - that's only for system jobs (i.e. /etc/crontab) — steeldriver, Feb 14 '18 at 13:34
I am using it as "user", which is how ideally the script should run. But in any case, it is strange the case with the echo, I am doing something wrong somwhere - unless cron @reboot only works woth root — user1156544, Feb 14 '18 at 13:35
Thanks @steeldriver, although this is not the error, because I have used it with no user field too — user1156544, Feb 14 '18 at 13:36
"This script calls other scripts that need sudo permissions" - this means you have to either run this as elevated user (root) or configure passwordless sudo. — Robert Riedl, Feb 14 '18 at 14:07
@RobertRiedl So what is the solution? I don't want to run as root, but the script needs to call other scripts as other users. And even the simple "echo" is not working. Also, I think both your links point to the same place. — user1156544, Feb 14 '18 at 15:24

score 4 · Answer 1 · answered Feb 14 '18 at 15:21

There is a big difference between reboot and login, and your system treats them both quite differently.

REBOOT jobs are run by the root user (not your user), and must be headless (no display). The best way to do boot-time jobs in 16.04 and newer is to create a service, and include that service in the appropriate systemd target during the boot process.
LOGIN jobs are run by your user (not root) after you enter your password. The best way to do login jobs is to place them in your ~/.config/autostart/ directory.

But you have a second problem. You seem to want a user-level job to use root-level services. There are many, many ways to do this.

The easiest way is to simply run your script as root manually every day. You already know how to do this, so let's look at other options.
The fastest way is to hack at the sudoers file and generate a special permission set. However, it may not backup properly with the rest of your system, AppArmor may block some actions anyway, and it's hard to troubleshoot and maintain.
The appropriate way is to separate your user-level and root-level functions into two separate scripts, and to use dbus to launch the root-level script and return it's output. This is easy to maintain and troubleshoot, but requires the greatest skill and a bit of learning about dbus.

That was insightful. I found another option for LOGIN jobs, which is the use of .profile (it needs the user to log in). I will do some testing and post the result — user1156544, Feb 14 '18 at 16:49

Running script via crontab on reboot

1 Answers1