Source code for an exercise in Unix concepts. https://lamda.blog/2019/01/27/jobs-and-pipes/

colors

# Export escape sequences for terminal colors.

# set colors with max compatibility
if tput setaf 1 &> /dev/null; then
  tput sgr0
  BLACK=$(tput setaf 0)
  RED=$(tput setaf 1)
  GREEN=$(tput setaf 2)
  YELLOW=$(tput setaf 3)
  BLUE=$(tput setaf 4)
  MAGENTA=$(tput setaf 5)
  CYAN=$(tput setaf 6)
  WHITE=$(tput setaf 7)
  BOLD=$(tput bold)
  RESET=$(tput sgr0)
else
  BLACK="\033[1;30m"
  RED="\033[1;31m"
  GREEN="\033[1;32m"
  YELLOW="\033[1;33m"
  BLUE="\033[1;34m"
  MAGENTA="\033[1;35m"
  CYAN="\033[1;36m"
  WHITE="\033[1;37m"
  BOLD=""
  RESET="\033[m"
fi

# export environment variables
export BLACK
export RED
export GREEN
export YELLOW
export BLUE
export MAGENTA
export CYAN
export WHITE
export BOLD
export RESET

listen

#!/bin/bash

PORT=$1

# Sleep for a couple of seconds
sleep_some() {
	number=$RANDOM
	let "number %= 2"
	let "number += 1"
	sleep $number
}

# Simulate server by "waiting" for incoming connections that randomly request
# one of three resources.
main() {
	sleep_some
	number=$RANDOM
	let "number %= 4"
	case $number in
		0) echo "GET /index.html HTTP/1.1 (200)";;
		1) echo "GET /foo HTTP/1.1 (404)";;
		2) echo "GET /private HTTP/1.1 (403)";;
		3) echo "FATAL ERROR. Terminating."; exit 1;;
	esac
	main
}

echo Listening on port ${PORT}…
main

namespace

#!/bin/bash

NAME=$1
COLOR=$2

while IFS='' read -r line || [[ -n "$line" ]]; do
    echo -e "$COLOR[$NAME]: $RESET$line"
done

run

#!/bin/bash

# Ensure colour-coding variables are available
. ./colors

send() {
	echo "$1" | ./namespace runner $RED
}

# Kill spawned jobs before exiting
trap 'send "Terminating…" && kill `jobs -p` 2>/dev/null' EXIT

send "Spawning fake servers…"
./listen 8000 | ./namespace web_01 $GREEN &
./listen 8001 | ./namespace web_02 $BLUE &
wait