bash handle SIGINT (https://stackoverflow.com/a/67498490)

sigint.sh

#!/bin/bash

# Will be set to 1 by the SIGINT ignoring/postponing handler
declare -ig SIGINT_RECEIVED=0
# On <CTRL>+C or "kill -s SIGINT $$" set flag for later examination
function _set_SIGINT_RECEIVED {
    SIGINT_RECEIVED=1
}

# Set to 1 if you want to keep bash running after handling SIGINT in a particular way
#  or to 0 (or any other value) to run original SIGINT action after postponing SIGINT
ignore_SIGINT_after_handling=1

# Remember current SIGINT handler
old_SIGINT_handler=$(trap -p SIGINT)
# Prepare for later restoration via ${old_SIGINT_handler}
old_SIGINT_handler=${old_SIGINT_handler:-trap - SIGINT}

# Start your "transaction", which should NOT be disturbed by SIGINT
trap -- '_set_SIGINT_RECEIVED' SIGINT

    # Do your work, for eample 
    (./program) &
    programPID=$!
    wait ${programPID}
    while [ $? -ge 128 ]; do
       # 1st opportunity to place a part of your **handler actions** is here
       # i.e. send SIGINT to ${programPID} and make sure that it is only sent once
       # even if MAIN receives more SIGINT's during this loop
       wait ${programPID}
    done

# End of your "transaction"
# Look whether SIGINT was received
if [ ${SIGINT_RECEIVED} -eq 1 ]; then
    # Your postponed **handler actions** are here
    echo -e "\nMAIN is doing postponed work now..."
    if [ ${ignore_SIGINT_after_handling} -eq 1 ]; then
        echo "... and continuing with normal program execution..."
    else
        echo "... and restoring old SIGINT handler and sending SIGINT via 'kill -s SIGINT \$\$'"
        ${old_SIGINT_handler}
        kill -s SIGINT $$
    fi
fi

# Restore "old" SIGINT behaviour
${old_SIGINT_handler}
# Prepare for next "transaction"
SIGINT_RECEIVED=0
echo ""
echo "This message has to be shown in the case of normal program execution"
echo "as well as after a caught and handled and then ignored SIGINT"
echo "End of MAIN script received"