Clean up return value file

dotfiles/bash/post.bashrc

 ### '''' ###
 
 __make_ps1d() {
-    lastrv=$(cat /var/tmp/bash-rv/$$.lastrv)
+    rvfile="/var/tmp/bash-rv/$$.lastrv"
+    lastrv=$(cat $rvfile)
     if [ $lastrv -gt 0 ];
     then
         echo "$lastrv"
     else
         echo ""
     fi
+    rm $rvfile
 }
 
 __save_rv() {