A simple way to spin up many blocking bash commands at once, killing all on SIGINT

bash-compose-up

#!/usr/bin/env bash

#
# This is a basic script to launch multiple programs and kill them
# all at the same time. It does this by launching the first n-1 jobs as
# background jobs, then running the nth job as a foreground job.
#
# It traps the exist signal produced by doing `CTRL-C` on the CLI and
# iterates through the PIDs of the background jobs and runs kill -9 on them.
#
# This script also tries to print our the results of each script with
# some color coding to make the outputs of these scripts somewhat readable.
#
# Requirements:
#   - Bash v4 or higher
#
set -e

declare -A PROGRAMS=(
  ["UI"]="PYTHONUNBUFFERED=TRUE python -m http.server 5001"
  ["API"]="npx http-server"
)

declare -A PIDS

NUM_PROGRAMS=${#PROGRAMS[@]}
COUNT=0
ESC=$(printf '\033')

# Start the background jobs
for NAME in "${!PROGRAMS[@]}"
do
  COUNT=$((COUNT + 1))
  COLOR=$((31 + COUNT))
  echo "Starting program ${ESC}[${COLOR}m$NAME${ESC}[0m: ${ESC}[2m${PROGRAMS[$NAME]}${ESC}[0m"
  if [ "$COUNT" != "$NUM_PROGRAMS" ]
  then
    eval "${PROGRAMS[$NAME]}" |& sed -e "s/^/${ESC}[${COLOR}m$NAME	|${ESC}[0m /" &
    PIDS[$NAME]=$!
  fi
done

# Trap and kill the background jobs
trap onexit INT
function onexit() {
  echo
  echo "Shutting down $NAME..."
  for NAME in "${!PIDS[@]}"
  do
    echo "Shutting down $NAME..."
    kill -9 "${PIDS[$NAME]}"
  done
}

# Start the final foreground job
#  NOTE: that $NAME is set to the last value in the loop
eval "${PROGRAMS[$NAME]}" |& sed -e "s/^/${ESC}[${COLOR}m[$NAME]${ESC}[0m /"