gibatronic · October 26, 2018 12:58 · Oct 26, 2018
diff --git a/README.md b/README.md
@@ -0,0 +1,13 @@
+# Proper job control in Bash scripts
+
+Simple example of how to properly launch background jobs and then gracefully terminate them.
+
+## Gotchas
+
+1. We could trap only the `EXIT` signal, but then after killing workers we get an unwanted "Terminated" message.
+2. In worker scripts, we must call `exit` when cleaning, to break out of the infinite loop
+3. After killing a worker, we still have to wait for them to gracefully terminate.
+
+## Further reading
+
+* [Job Control Commands](http://www.tldp.org/LDP/abs/html/x9644.html)
diff --git a/main b/main
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+clean() {
+	echo
+	kill $(jobs -pr)
+	wait
+	echo 'main clean'
+}
+
+main() {
+	local self="$0"
+	local base="$(dirname "$self")"
+
+	trap 'clean' 'SIGINT' 'SIGTERM'
+
+	"$base/worker" 'A' &
+	"$base/worker" 'B' &
+	"$base/worker" 'C' &
+
+	wait
+}
+
+main "$@"
diff --git a/worker b/worker
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+clean() {
+	local name="$1"
+
+	echo "worker $name clean"
+	exit 0
+}
+
+main() {
+	local name="$1"
+
+	trap "clean '$name'" 'SIGINT' 'SIGTERM'
+
+	while true; do
+		sleep "$(($RANDOM % 5 + 1))"
+		echo "worker $name tick"
+	done
+}
+
+main "$@"