UNIX for Advanced & Expert Users

$ myscript &

#!/bin/bash
if [[ -z ${1+set} ]]; then
    echo "Missing argument"
    exit 1
fi
echo "Arguments OK, going to background"
some_command_that_sends_the_script_to_background
# At that point, the user should have its terminal back and the script should be sent to bg
while true; do
    echo "doing some never ending daemon stuff" > log
    sleep 5
done

bg
disown
exec &

(
while true; do
    echo "doing some never ending daemon stuff" > log
    sleep 5
done
) </dev/null >/dev/null 2>&1 &

#!/bin/bash

if [[ -z ${1+set} ]]
then
        echo "Missing argument" >&2
        exit 1
fi

# Check if we're a background script
if [ -z "${_FG}" ]
then
        # Warn subshell that it is a subshell
        export _FG="1"

        # Re-run entire script and warn it that its a subshell
        ( exec "$0" "$@" ) &
        exit 0
fi

# This code will run in background
echo "Yeah okay we're in subshell"
sleep 10
echo "Woo"