Why does sudo su not work in my script?

Adalbert Hanßen

1/1/23, 1:36 PM

I want to change ownership, group membership and access rights in a script by a sequence of commands.

Some of them need root permissions.

I first did sudo su in a terminal and then ran all the necessary commands once in a row. I found out that after sudo su all macro definitions abc=<...> have to be put after sudo su, because it seems that root does not know about macros existing in the other context.

After all my commands worked as expected, I called histoy, removed the line numbers and framed the relevant part of it in sudo su ... exit.

I can paste this sequence of commands into a terminal and it runs fine.

However if I prepend it with a line #!/bin/bash and store it as a file and make that executable, that does not work:

I get prompted for the password, but then I end up at a command line level, with the prompt ending in #, which shows me that sudo su has worked. But the rest of my command sequence has not worked.

How can I achieve the other commands to be executed?

Being a command line newbie, I guess I haven't understood something important yet. Please explain how to do it and why.

0 + 3

command-line

sudo

scripts

Artur Meinild

1/1/23, 1:47 PM

Don't use `sudo` inside scripts. Instead, run the entire script as root. If it's a cronjob, run it from root's crontab.

Adalbert Hanßen

1/1/23, 2:28 PM

Artur, do you suggest to put `sudo -u <username>` in front of all non-privileged commands and run the whole script as `sudo xyz.sz`? This however contradicts your first advice to never use sudo within a script.

Artur Meinild

1/1/23, 6:56 PM

I didn't say never, I said "don't". But the one example you give would be the exception, and that could be viable in some cases. ;-)