Running process as another user

[morgon]

Hi,

I have a script that is started by udev and so runs as root. What I want the script to do is to fork off another long-running process that is supposed to run as another user.

Here is what I do at the moment:

if(fork()) {
# do some stuff in the parent as root
}
else {  # child - run process as another user
exec "/usr/bin/sudo -u some_other_id $command_to_run"
}

This works but in the process table I end up with 2 processes: One for the started command running as some_other_id and a root-process for the sudo.

My question is now how to avoid having the sudo-process staying around.

To rephrase: How do you fork off a long-runnning process under an other user-id while avoiding a root-owned sudo-process staying around as well.

Please note that I want the new process to appear in the process-table as beloning to the other user, so setting effective uid does not do the trick as the process would still appear as root in ps.

Many thanks!

[Corion]

Looking at perlvar for $< and $>, it suggests that you may want to call POSIX::setuid() to set both in one call. Would that work for you? Or would simply setting both, $< and $> work for you, too?

($<,$>)= ($run_as, $run_as);

or

use POSIX qw(setuid);

setuid( $run_as );

[morgon]

I actually mentioned in my post why this is not what I want.

The problem with this approach is that the resulting process (while running under the correct effective user-id) still seems to be running as root in ps.

I would like to have a process running under another effective id and be visible as such in ps.

[Corion]

Ah - I'm sorry, I thought that one was for setting the real user-id in addition to the effective user-id would have that effect.

[mhearse]

Have udev call:

#!/bin/bash
sudo su - some_other_uname
# validate with whoami or id if desired

# run your command in the background
/usr/bin/yourcommand > /dev/null 2>&1 &

# script exits... but your command lives on.... running as the desired
+ user.
# forever zorked

[Anonymous Monk]

Don't know how to do it in Perl but the usual approach seems to be to fork a process that setuid's to another user, then execs the target.