In unix shell scripting how the exception handling is done.

You check the return codes of various commands using the $? environment variable. This variable contains the exit status of the previous command.

You could also look at the 'trap' command, which you can use to set up conditions for when a particular signal is returned from a process.

e.g.

trap 'doSomeStuff' 1 2 15

(where 1, 2 and 15 are exit statuses you would like to be caught by the trap)