Backup to thumbdrive on a Mac which ignores folders which do not need a backup like Dropbox and GitHub

backup.sh

#!/bin/sh

# set the strict mode
set -e

if [ -d "/Volumes/Thumbdrive" ]; then

if [ ! -d "/Volumes/Thumbdrive/Backups" ]; then
    mkdir "/Volumes/Thumbdrive/Backups"
fi

if [ ! -d "/Volumes/Thumbdrive/Backups/MacBook Pro" ]; then
    mkdir "/Volumes/Thumbdrive/Backups/MacBook Pro"
fi

rsync -av \
    -del \
    --exclude "/Documents/VMware/" \
    --exclude "/Documents/Projects/GitHub/" \
    --exclude "/Documents/Projects/Subversion/" \
    --exclude "/Downloads/" \
    --exclude "/Dropbox/" \
    --exclude "/Library/" \
    --exclude "/Music/" \
    --exclude ".DS_Store" \
    --exclude "/.vagrant.d" \
    --exclude "/.Trash" \
    --exclude "/.gem" \
    --exclude "/.dropbox" \
    --exclude "/.cocoapods/" \
    ~/ "/Volumes/Thumbdrive/Backups/MacBook Pro/"

ls -lsa "/Volumes/Thumbdrive/Backups"
else
    echo "Thumbdrive is not connected"
fi