How to switch user root to user to root to kill parent process?

Question

I am developing a complicated automation script that will automate a large portion of my build, install, deploy and post installation processes. The problem is that within all of the commands that need to be issued, there is one that requires the user to be root. (This is a requirement constraint as is the need for the other user (we'll call user1) to not be on the sudoers list)

Basically the way I am structuring my scripts is, I have a starting script that must be run as root. This script will call two other scripts as user1.

All three scripts share a sharedFunctions.sh script that defines common functions. Within this script I have a run_command function that needs to take a command and a failure string among other arguments that are unimportant to this problem.

Now if the failure string appears in the output of the given command, I want to kill the parent process stopping the entire train. I have an exported variable of the parent PID that I grab from the root script, but if the script fails while it is running either of the two user1 scripts, I cannot kill that process because it is owned by root.

Is there a way to "exit" back to root without it requiring credentials (similar to how you can in the terminal) so I can kill the PID owned by root?

*****EDIT*****

This is the very simplified process that my script needs to follow formatted as such (required user:function):

user1:maven install
user1:scp jars to chef server
root:chef command
user1:chef command
user1:post-installation scripts

I have three scripts and one sourced script

user1cmd1.sh parentscript.sh user1cmd2.sh sharedFunctions.sh

the parentscript.sh first extracts the PID by using export TOP_PID=$$ it then calls user1cmd1.sh as user1 when that script finishes, it returns to the parentscript and as root the chef command is run it then calls user1cmd2.sh as user1

my run_command which is defined in sharedFunctions.sh is scripted similar to this:

run_command(){
    cmd=$1
    fail=$2
    if $cmd | grep -q $fail;then
         kill $TOP_PID #there is more to this particular command, but I don't have it in front of me
    fi
}

Answer 1

parentscript.sh could create a reaper process to which it passes $TOP_PID. The reaper process would attempt to read from a named pipe which is writeable by user1. If nothing is written to the pipe the reaper just blocks on the read and does nothing else, but if anything is written to the pipe the reaper's read completes and the reaper goes onto the rest of its code, killing the top process.