CODEWITHSUNDEEP
shellsignalsexit-codeshell-trap
jpou
jpou

Reputation: 1995

trapping shell exit code

I am working on a shell script, and want to handle various exit codes that I might come across. To try things out, I am using this script:

#!/bin/sh
echo "Starting"
trap "echo \"first one\"; echo \"second one\"; " 1
exit 1;

I suppose I am missing something, but it seems I can't trap my own "exit 1". If I try to trap 0 everything works out:

#!/bin/sh
echo "Starting"
trap "echo \"first one\"; echo \"second one\"; " 0
exit

Is there anything I should know about trapping HUP (1) exit code?

Upvotes: 3

Views: 2713

Answers (3)

Dennis Williamson
Dennis Williamson

Reputation: 360143

That's just an exit code, it doesn't mean HUP. So your trap ... 1 is looking for HUP, but the exit is just an exit.

In addition to the system signals which you can list by doing trap -l, you can use some special Bash sigspecs: ERR, EXIT, RETURN and DEBUG. In all cases, you should use the name of the signal rather than the number for readability.

Upvotes: 2

fa.
fa.

Reputation: 2486

You can also use || operator, with a || b, b gets executed when a failed

#!/bin/sh

failed
{
    echo "Failed $*"
    exit 1
}

dosomething arg1 || failed "some comments"

Upvotes: 0

Charles Stewart
Charles Stewart

Reputation: 11837

trap dispatches on signals the process receives (e.g., from a kill), not on exit codes, with trap ... 0 being reserved for process ending. trap /blah/blah 0 will dispatch on either exit 0 or exit 1

Upvotes: 5

Related Questions