Add envvar to disable logging

In case shit gets spammy or whatever

firestarter

@@ -259,6 +259,10 @@ Start or generate a desktop environment configuration
   -d		Perform a dry run. This will print the results of all decisions
 		without executing them.
 
+Additionally, firestarter responds to the following environment variables:
+
+  FS_NOLOG	If nonempty, create no log files
+
 Copyright (c) 2019 rehashedsalt@cock.li
 Licensed under the MIT License
 https://gitlab.com/rehashedsalt/firestarter
@@ -343,7 +347,9 @@ step_execute() {
 			err "Failed to create configuration directory \"$g_configdir\"" 52
 		fi
 	fi
-	if ! [ -d "$g_logdir" ]; then
+	if [ -n "$FS_NOLOG" ]; then
+		log "No logs will be created per FS_NOLOG"
+	elif ! [ -d "$g_logdir" ]; then
 		if ! mkdir -p "$g_logdir" > /dev/null 2>&1; then
 			err "Failed to create log directory \"$g_logdir\"" 53
 		fi
@@ -366,8 +372,9 @@ step_execute() {
 			step_execute
 			break
 		fi
-		filename="$(basename -- "$file")"
-		logfile="$g_logdir/$filename"
+		local filename="$(basename -- "$file")"
+		local logfile="$g_logdir/$filename"
+		[ -n "$FS_NOLOG" ] && logfile="/dev/null"
 		# Every odd line is the check line
 		# Every even one is the exec line
 		while read -r checkline; do