Color prompt dollar based on last return value

dotfiles/bash/head.bashrc

 #!/bin/bash
 
+mkdir -p /var/tmp/bash-rv
+
 for include in \
   "${HOME}/.bash/colors.bashrc" \
   "${HOME}/.bash/main.bashrc" \

dotfiles/bash/post.bashrc

 ### BASH ###
 ### '''' ###
 
+__make_ps1d() {
+    lastrv=$(cat /var/tmp/bash-rv/$$.lastrv)
+    if [ $lastrv -gt 126 ];
+    then
+        echo " \$"
+    elif [ $lastrv -gt 0 ];
+    then
+        echo " \$"
+    else
+        echo " \$"
+    fi
+}
+
+__save_rv() {
+    echo $1 > /var/tmp/bash-rv/$$.lastrv
+}
+
 make_ps1() {
     # these functions must be already defined by ~/.bash/user/*.bashrc
     # and ~/.bash/host/*.bashrc
+    svrc='$(__save_rv $?)'
     ps1u=$(make_ps1u)
     ps1h=$(make_ps1h)
     ps1w="$lblue\w$normal";
     ps1G='$(__git_ps1 "(%s)")';
     ps1g="$green$ps1G$normal";
-    echo "$ps1u@$ps1h:$ps1w$ps1g$normal\$ ";
+    ps1D='$(__make_ps1d $?)';
+    ps1d="$ps1D";
+    echo "$svrc$ps1u@$ps1h:$ps1w$ps1g$ps1d$normal ";
 }
 
 make_ps2() {