Trigger i3lock by udev rules.

.local/bin/i3hwlock

@@ -0,0 +1,109 @@
+#!/bin/bash
+
+# i3hwlock
+#
+# Allows locking i3 by the presence of a file. This file is intended to be
+# created using udev rules so that you can trigger the lock when you remove
+# a device such as a YubiKey. Example rule below.
+#
+# /etc/udev/rules.d/99-i3hwlock-yubikey.rules:
+# ACTION=="add", SUBSYSTEM=="input", ENV{ID_VENDOR_ID}=="1050", RUN+="/usr/bin/rm /tmp/i3hwlock.trigger"
+# ACTION=="remove", SUBSYSTEM=="input", ENV{ID_VENDOR_ID}=="1050", RUN+="/usr/bin/touch /tmp/i3hwlock.trigger"
+
+LOCK_TIMEOUT=3 # How many seconds to wait before locking.
+DMENU_FILE="/tmp/i3hwlock"
+TRIGGER_FILE="$DMENU_FILE.trigger"
+ABORT_FILE="$DMENU_FILE.abort"
+CONTINUE_FILE="$DMENU_FILE.continue"
+LOCKING_FILE="$DMENU_FILE.locking"
+
+function check_prerequisites() {
+	[ -e "$ABORT_FILE" ] && rm "$ABORT_FILE"
+
+	if ! which inotifywait >/dev/null; then
+		echo "ERROR: inotifywait not found." 1>&2
+		return 1
+	fi
+}
+
+function dmenu_selection() {
+	selection="$(xargs -n 1 <<<"Continue Abort" | dmenu -i -p "The screen is about to lock")"
+	[ -z "$selection" ] && return
+	file="$DMENU_FILE.${selection,,}"
+	echo "INFO: Touching $file"
+	touch "$file"
+}
+
+function abort_lock() {
+	[ -e "$ABORT_FILE" ] && rm "$ABORT_FILE"
+
+	if ! [ -f "$LOCKING_FILE" ]; then
+		echo "WARN: Abort initiated without file '$LOCKING_FILE'." 1>&2
+		return 0
+	fi
+
+	echo "INFO: Aborting lock."
+	killall dmenu
+	notify-send "Lock aborted." &
+	[ -e $LOCKING_FILE ] && rm "$LOCKING_FILE"
+}
+
+function lock() {
+	[ -e "$CONTINUE_FILE" ] && rm "$CONTINUE_FILE"
+
+	if ! [ -f "$LOCKING_FILE" ]; then
+		echo "WARN: Won't lock as file '$LOCKING_FILE' is missing." 1>&2
+		return 0
+	fi
+
+	echo "INFO: Locking now."
+	killall dmenu
+	i3exit lock 2>/dev/null || i3lock --color=29414f --nofork
+	[ -e $LOCKING_FILE ] && rm "$LOCKING_FILE"
+}
+
+function delayed_lock() {
+	echo "INFO: Delayed lock initiated."
+	touch "$DMENU_FILE.locking"
+
+	for i in $(seq $LOCK_TIMEOUT); do
+		notify-send "Locking in $((LOCK_TIMEOUT - i + 1))" -t 1000 &
+		sleep 1
+
+		if [ -e "$ABORT_FILE" ]; then
+			abort_lock
+			return 0
+		elif [ -e "$CONTINUE_FILE" ]; then
+			break
+		fi
+	done
+
+	! [ -e $LOCKING_FILE ] && return 0
+	lock
+}
+
+function listen() {
+	while read -r directory action file; do
+		if [[ "$file" == "${TRIGGER_FILE##*/}" ]]; then
+			if [[ "$action" == "CLOSE_WRITE,CLOSE" ]] && ! [ -e "$LOCKING_FILE" ]; then
+				$0 dmenu-selection &
+				$0 delayed-lock &
+			elif [[ "$action" == "DELETE" ]]; then
+				abort_lock
+			fi
+		fi
+	done < <(inotifywait -m "${TRIGGER_FILE%/*}")
+}
+
+check_prerequisites || exit 1
+
+if [ -z "$1" ]; then
+	listen || exit 2
+elif [[ "$1" == delayed-lock ]]; then
+	delayed_lock || exit 3
+elif [[ "$1" == dmenu-selection ]]; then
+	dmenu_selection || exit 4
+else
+	echo "ERROR: Unrecognized action: '$1'." 1>&2
+	exit 127
+fi