Executing a task after the first update

mr.simo · 10-24-2014, 02:06 AM

Hi,

I need to update a Linux system and execute a task after a reboot.

The process is as follow:

1) The updates are downloaded from a known URL in a specific folder.
2) The machine is rebooted and during the startup, in a file placed in the properly rcN.d directory, the files are replaced with the older ones.

Basically, I have to change some permissions over the entire filesystem during the step 2.

I could place another file into the updates and successfully place it in the rcN.d directory but this will not be executed in step #2 but at the next reboot.

How can I solve my little problem ?

Thank you in advance.

zhjim · 10-24-2014, 02:19 AM

Two ways come to my mind. You can use the rc.local file to do what you want after the reboot. You just have to remove the call to the update programm after its done its job.
Or you could use cron with the @reboot stanca. Heres a nice link: http://www.cyberciti.biz/faq/linux-e...system-reboot/

mr.simo · 10-24-2014, 03:23 AM

I solved including the permissions chmod and chown instructions into another shell script, let's call it file.sh.

Then I removed the chmod and chown lines from the same script with sed, inside the same file file.sh:

Code:

#!/bin/bash

# file.sh

chmod -R xxx /path/to/files
chown -R user:usergrp /path/to/files
sync

sed -i '/chown -R root:root/d' /path/to/file.sh
sed -i '/chmod/d' /path/to/file.sh
sed -i '/sync/d' /path/to/file.sh
sed -i '/sed/d' /path/to/file.sh

It works like a charm.

zhjim · 10-24-2014, 06:21 AM

Nice work. So how do the call the script in the first place?

mr.simo · 10-25-2014, 05:51 AM

The script file.sh was already launched by default by another script in the rcN.d directory, let's call it S01xxx.

Another solution (avoiding to use a pre-existent script file.sh) is to substitute the same script S01xxx with another where the unique difference is to check if a particularly file file2.sh exists, and then execute it.. You can remove the same file2.sh by himself at the end of the file2.sh once it has executed one time..

zhjim · 10-27-2014, 03:11 AM

So the "usual" runlevel script approach. Good Job.