everything(){
echo "do stuff"
}

echo "What type of node are you on?"
echo "Type db for Database. Type app for Application. Type both for both."
print -n "Node: ";read var

case $var in
db)
echo "do db stuff"
;;
app)
echo "do app stuff"
;;
both)
everything
;;
*) 
echo "Wrong argument, bye bye ..."
exit 1
;;
esac