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shellsignalsexit-codeshell-trap

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?

Solution

  • 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