rework the regeneration mechanism for tmenu_run

builds/utils/tmenu_run

@@ -9,12 +9,11 @@ tmenu_path () {
     done
 }
 
-if [ "$(basename $0)" = "regenerate" ]; then
+export IS_RUNNING_IN_TMENU="yes"
+choice=$(cat $HOME/.local/share/tmenu_cache | tmenu)
+if [ -z "$choice" ]; then
 	mkdir -p $HOME/.local/share
-	tmenu_path > $HOME/.local/share/tmenu_cache
-	xmessage "regeneration complete"
-	exit
+	tmenu_path | sort > $HOME/.local/share/tmenu_cache
 else
-	export IS_RUNNING_IN_TMENU="yes"
-	cat $HOME/.local/share/tmenu_cache | tmenu | ${SHELL:-"/bin/sh"} &
+	/bin/sh -c $choice &
 fi