A script to add and remove a character in a line at a given time

Jason.nix · 01-31-2024, 02:46 AM

Hello,
I have a configuration file and I want a line from this configuration file to be converted to a comment (#) at a specified time, and then reset the service, and again at a specified time, that line is removed from comment mode and reset the service again. Is this possible with a script?

Thank you.

pan64 · 01-31-2024, 03:55 AM

yes
you need to create a crontab entry to run your script which will do that modification and reset/restart/reload the service again.
To change a line you can use a lot of tools, for example awk, sed, perl, python or even shell. Or you can just store the two versions and copy them at the given time.

GazL · 01-31-2024, 03:57 AM

Quote:

Originally Posted by pan64

Or you can just store the two versions and copy them at the given time.

... or flip the target of a symlink between them.

Jason.nix · 01-31-2024, 05:05 AM

Quote:

Originally Posted by pan64

yes
you need to create a crontab entry to run your script which will do that modification and reset/restart/reload the service again.
To change a line you can use a lot of tools, for example awk, sed, perl, python or even shell. Or you can just store the two versions and copy them at the given time.

Hello,
Thank you so much for your reply.
Can you help me write this script? I want a # sign to be placed at the beginning of line 214 of the /etc/tor/torrc file at 12:00 AM and then the systemctl restart tor command will be executed, then tomorrow at the same time the # sign will be removed and the service will be restarted.

Turbocapitalist · 01-31-2024, 06:12 AM

As mentioned in #3 above, you can make two extra copies of the torrc file. Then at the designated times you can have some scripts do two things: First copy one of the copies to the official torrc file. Second restart the service / reload the configuration file.

You can do that with two shell scripts (one for each file) and trigger it via a cron job.

If you are amenable to that approach, please give it a try.

MadeInGermany · 01-31-2024, 10:51 AM

One time actions are done with at jobs.
Next possible 12:00, in line 214 put a leading #

Code:

at 12:00 << _EOT_
PATH=/bin:/usr/bin:/sbin:/usr/sbin
sed -i '214 s/^/#/' /etc/tor/torrc
systemctl restart tor
_EOT_

One day later, in line 214 remove a leading #

Code:

at 12:00 + 1 day << _EOT_
PATH=/bin:/usr/bin:/sbin:/usr/sbin
sed -i '214 s/^#//'/etc/tor/torrc
systemctl restart tor
_EOT_

pan64 · 01-31-2024, 10:59 AM

Code:

sed -i '214 s/^\([^#]\)/#\1/' /etc/tor/torrc

just to be on the safe side