Is Exception handling possible in Unix shell script, which includes calling another scripts internally

Not sure if this works in sh, but it works in bash. I made a try / except tool out of this, but it will work here too I believe.

#! /bin/bash

try() {
    exec 2> /dev/null
    #direct stderr out to /dev/null

    #main block
    input_function="$1"

    #fallback code
    catch_function="$3" 

    #open a sub shell
    (

    #tell it to exit upon encountering an error
    set -e

    #main block
    "$@"

    )

    #if exit code of above is > 0, then run fallback code
    if [ "$?" != 0 ]; then
        $catch_function
    else
        #success, it ran with no errors
        test
    fi

    #put stderr back into stdout
    exec 2> /dev/tty
}

An example of using this would be:

try [function 1] except [function 2]

Function 1 would be main block of code, and 2 would be fallback function/block of code. Your first function could be:

run() {
  /path/to/external/script
}

And your second can be whatever you want to fall back on. Hope this helps.