Improve readability

app/tru

@@ -10,7 +10,7 @@
 # shellcheck disable=SC3043 # Uses local variables.
 # shellcheck disable=SC1091,SC2034 # File not following, appears unused.
 readonly \
-	BASE_APP_VERSION=0.9.20240105 \
+	BASE_APP_VERSION=0.9.20240109 \
 	BASE_MIN_VERSION=0.9.20240104
 . base.sh
 
@@ -64,12 +64,8 @@ validation() {
 	validate_cmd awk nc tr transmission-remote transmission-show
 	[ "$#" -eq 3 ] || die Usage: tru host:port user:pass torrent-file.
 
-	# Single : means there is no authentication data.
-	if [ "$2" != : ]; then
-		AUT="--auth $2"
-	else
-		AUT=''
-	fi
+	# Single ':' means there is no authentication data.
+	[ "$2" != : ] && AUT="--auth $2" || AUT=''
 	readonly \
 		AUT \
 		SER="$1" \