"Awaiting" D-Bus message in Bash

dbustest.sh

#!/usr/bin/env bash

# Senging expected message:
# dbus-send --session --type=signal /org/example/Test org.example.Test.TestSignal

set -euo pipefail

# Match the precise signal we’re interested in.
MATCH="type='signal',interface='org.example.Test',member='TestSignal'"

# Create a temporary FIFO to capture dbus-monitor output line-by-line.
FIFO=$(mktemp -u)
mkfifo "$FIFO"

cleanup() {
    rm -f "$FIFO"
}
trap cleanup EXIT

# Start dbus-monitor with a timeout so we don’t block forever.
timeout 15s dbus-monitor --session "$MATCH" >"$FIFO" &
MON_PID=$!

# Consume the monitor output; react only when the actual signal arrives.
while IFS= read -r line; do
    [[ $line == *"member=TestSignal"* ]] || continue
    echo "Signal received"
    kill "$MON_PID" >/dev/null 2>&1 || true
    exit 0
done <"$FIFO"

# If we fall out of the loop, the monitor ended (timeout or other error).
wait "$MON_PID" >/dev/null 2>&1 || true
echo "Timed out without signal"
exit 1