Do not delete rvfile by default

dotfiles/bash/post.bashrc

     local rvfile="/var/tmp/bash-rv/$$.lastrv"
     local lastrv
     read lastrv <<<$(cat $rvfile 2>/dev/null)
+    local do_rm=false
+    test "$1" == "-r" && do_rm=true
     if [ 0$lastrv -gt 0 ];
     then
-        echo "$lastrv"
+        echo "!$lastrv!"
     else
         echo ""
     fi
-    rm -f $rvfile
+    $do_rm && rm -f $rvfile
 }
 
 __save_rv() {