I use FAT32-formatted hard drives for cross-platform compatibility, but Time Machine doesn’t work with FAT32 drives. How can I automatically back up my data?

Rsync to the rescue! If you’re looking for superhuman-strength backups, learning a few rsync tricks can keep your Mac inoculated against all sorts of disasters. Rsync is a command-line Unix application for copying files, which you can run on your Mac in Terminal. You’ll find it in Applications > Utilities. Like Time Machine, you can use rsync to keep regular backups of all your files, and you can even automate the process.

Type man rsync to learn more than you ever wanted to know about copying files.

For a basic backup with rsync, you need to tell the application what to back up, and where to put it. Run this command (all on one line):
 
rsync --delete -r ~/Documents /Volumes/Backup

That tells your Mac to run rsync, copying anything in your Documents to a mounted external drive you’ve named Backup. (Terminal also lets you drag the volume in from the Finder to add it to the command, if you’re not sure how to type it yourself.) The “--delete” parameter tells rsync to delete any files in the destination location that you’ve deleted or moved from Documents, and “-r” tells rsync to recursively back up files and folders within Documents. But rsync can be used for much more specific backups, including file compression, differential backups (where only the updated files are changed), and more. Googling will lead to a number of good rsync tutorials online, or you can read the rsync manual in Terminal (type man rsync) to learn more.