Why my stop script is not being executed?

I recently got a question on why his Linux script is not executed when the system is rebooted or shutdown.
The script runs fine when run manually.

# service cleanscript stop
Cleanscript:  Cleaning up the directory!

My quick response was maybe your script is not configured correctly for systemd. Upon further inspection the 
server is running a Redhat 6 update 10 OS. This was still using the old init scripts.

Here is the script in question.

#!/bin/sh
#
stop() {
    echo -n $"Cleanscript: Cleaning up the directory!"
   rm -fr /var/tmp/*
}

case "$1" in
    stop)
        stop
        ;;
esac
 

I can see the problem that the script have no start function. He came back as to why does it need a start function, when the script is only needed when the server is being shutdown?
If you look at the script  /etc/rc.d/rc that executes all the stop scripts, you have these lines.
It looks for a lock file, if it can't find the lock file it just ignore the script.

# First, run the KILL scripts.
for i in /etc/rc$runlevel.d/K* ; do

        # Check if the subsystem is already up.
        subsys=${i#/etc/rc$runlevel.d/K??}
        [ -f /var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] || continue
        check_runlevel "$i" || continue
 

Here is the corrected script.

#!/bin/sh
#

start() {

      echo "Cleanscript: creating the lock file"
     touch /var/lock/subsys/cleanscript

}

stop() {
    echo "Cleanscript: Cleaning up the directory"
   rm -fr /var/tmp/*
  rm -f /var/lock/subsys/cleanscript
   
}

case "$1" in
    stop)
        stop
        ;;

start)
        start
        ;;
esac

Now, add the startup for cleanscript in runlevel 3.

#ln -s /etc/init.d/cleanscript /etc/rc3.d/S99cleanscript

How do you do this with systemd?

Starting with RHEL 7 it comes with a more flexible systemd for managing your services.

You will need to create these two files. The actual clean up script and the service definition.

# pwd
/etc/systemd/system

# ls -l cleanscript*
-rw-r--r--. 1 root root 211 Aug 21 21:34 cleanscript.service
-rwxr-xr-x. 1 root root  79 Aug 21 21:33 cleanscript.sh

# cat cleanscript.service

[Unit]
Description=Cleanscript: Clean up the /var/tmp directory

[Service]
Type=oneshot
RemainAfterExit=true
ExecStart=/bin/true
ExecStop=/etc/systemd/system/cleanscript.sh

[Install]
WantedBy=multi-user.target

# cat cleanscript.sh
 

#!/bin/sh
echo -n $"Cleanscript: Cleaning up the directory!"
rm -fr /var/tmp/*

# systemctl enable cleanscript
Created symlink from /etc/systemd/system/multi-user.target.wants/cleanscript.service to /etc/systemd/system/cleanscript.service.

# systemctl status cleanscript
â cleanscript.service - Cleanscript: Clean up the /var/tmp directory
   Loaded: loaded (/etc/systemd/system/cleanscript.service; enabled; vendor preset: disabled)
   Active: inactive (dead)
# systemctl start cleanscript
# systemctl status cleanscript
 cleanscript.service - Cleanscript: Clean up the /var/tmp directory
   Loaded: loaded (/etc/systemd/system/cleanscript.service; enabled; vendor preset: disabled)
   Active: active (exited) since Tue 2018-08-21 21:42:00 PDT; 2s ago
  Process: 1330 ExecStart=/bin/true (code=exited, status=0/SUCCESS)
 Main PID: 1330 (code=exited, status=0/SUCCESS)

Aug 21 21:42:00 workstation1 systemd[1]: Starting Cleanscript: Clean up the /var/tmp directory...
Aug 21 21:42:00 workstation1 systemd[1]: Started Cleanscript: Clean up the /var/tmp directory.