bash background

00-readme.md

$ ./bash-background
forked sleep in the background as pid 42335
program is running
waiting for pid 42335...
sleep exited with code 0
program has exited

bash-background.sh

#!/usr/bin/env bash

# fork sleep in the background
sleep 3 &
pid=$!
echo "forked sleep in the background as pid $pid"

# check if program running (should be running)
if kill -0 "$pid" 2>/dev/null; then
	echo "program is running"
else
	echo "program has exited"
fi

# wait for sleep to finish and get its exit code
echo "waiting for pid $pid..."
wait "$pid"
code=$?
echo "sleep exited with code $code"

# check if program running (should NOT be running)
if kill -0 "$pid" 2>/dev/null; then
	echo "program is running"
else
	echo "program has exited"
fi