devstack/tools/xen/scripts/on_exit.sh

#!/bin/bash

set -e
set -o xtrace

if [ -z "${on_exit_hooks:-}" ]; then
    on_exit_hooks=()
fi

on_exit()
{
    for i in $(seq $((${#on_exit_hooks[*]} - 1)) -1 0); do
        eval "${on_exit_hooks[$i]}"
    done
}

add_on_exit()
{
    local n=${#on_exit_hooks[*]}
    on_exit_hooks[$n]="$*"
    if [[ $n -eq 0 ]]; then
        trap on_exit EXIT
    fi
}