Korn Shell Programming by Example

Defining and Using Traps

As you will see, your script can trap for errors and the exit condition. These are probably the most commonly trapped-for events. Can other things be trapped? Let's answer that by examining the meaning of a trap.

Traps are typically described as asynchronous events. The event is asynchronous because of its unpredictability. An example is a Ctrl+C being pressed while your script is running. The event of the Ctrl+C is totally unpredictable from the perspective of your script. During one run, it might occur after 20 seconds; during another run, it might occur after 2 hours. And during a third run, it might not occur at all.

You may be thinking that a Ctrl+C causes an interrupt, not a trap. The trap is the action of reacting ...