Call Script on Script Exit

[GaToRAiD]

I'm trying to figure out how I can call a script as one exits. I do not want to run the script inside of the other script. I want it to call the next one as it exits. I'm not sure if this can be done. Here is a better representation of it.

First Script runs
Exits - Calls Second Script
Second Script runs
exits - Calls Third
etc
etc
etc

[GaToRAiD · Accepted solution]

Ouch, just figured it out, I will load a launch daemon just before exiting. This daemon will call the script.

[BrysonTyrrell · Accepted solution]

You could also use "trap" in each script which is a shell builtin.

#!/bin/bash

# Define a function to call for the trap
OnExit() {
    run script
    # or execute policy
}

# Tell the script to call the function when an exit signal occurs
trap OnExit exit

# Do the script's stuff
do a command
do a command

# Now on exit it will always trigger the above function
exit 0

I have more fleshed out examples in a post I did here:
http://bryson3gps.wordpress.com/2013/11/10/bash-favorites/

[GaToRAiD · Accepted solution]

Ouch, just figured it out, I will load a launch daemon just before exiting. This daemon will call the script.

[BrysonTyrrell · Accepted solution]

You could also use "trap" in each script which is a shell builtin.

#!/bin/bash

# Define a function to call for the trap
OnExit() {
    run script
    # or execute policy
}

# Tell the script to call the function when an exit signal occurs
trap OnExit exit

# Do the script's stuff
do a command
do a command

# Now on exit it will always trigger the above function
exit 0

I have more fleshed out examples in a post I did here:
http://bryson3gps.wordpress.com/2013/11/10/bash-favorites/

[talkingmoose · Accepted solution]

Adding an ampersand at the end of a line in a script will run that process in the background and should allow your new forked process to continue although your script is exited.

#!/bin/sh
    run stuff in your script
    sh /path/to/another/script.sh &
exit 0

A downside to this method is you can't easily return any results to the JSS from the forked process.

[alexjdale]

Did something change with Bash or the way the JSS runs scripts? I cannot for the life of me get a thread to fork or a trap to execute on exit without Casper waiting for it to complete while I am trying to schedule a restart, which means the policy log never gets uploaded to the JSS (the restart interrupts it). My tests work fine outside of Casper.

I am thinking a launchdaemon is my only option. I would use a policy-driven restart, except the restart occurs even if the policy fails, which is very bad for my needs.

[nessts]

I moved a lot of postinstall stuff into running out of launchdaemon just for that express reason that the casper policy finishes successfully, and what I need to happen at the back end finishes. I usually have my recon built in the postinstall if I need the database updated as well.

[alexjdale]

Yeah, I just built a launchdaemon to run a script for my reboot, and that solved it.