How do you use rsync on a Mac to back up a folder?

By Kayabyte · Last updated 13 November 2026

Short answer: Run rsync -avn source/ destination/ to see what would be copied, then run it again without the n to copy. Keep the slash after the source folder. Add --delete only when you want the destination to lose files you removed, and only after a dry run. rsync is free and built in, but it has no preview window, no archive of deleted files unless you add options, and no memory of the last sync. Pairfold is a Mac app that covers those gaps for pairs of folders.

Which rsync is it?

On the Mac we checked (macOS 27, 13 November 2026) rsync --version prints “openrsync: protocol version 29, rsync version 2.6.9 compatible”. Apple’s built-in rsync is a rewrite, and the options listed on its man page are fewer than in current rsync from Homebrew. Tutorials may use options that are not there. Run man rsync on your Mac to see yours.

The options that matter

-a archive: keeps dates, permissions and links.
-v lists what is copied. -n (--dry-run) changes nothing.
--delete removes files from the destination that are not in the source.
--backup --backup-dir=/absolute/path moves replaced and deleted files into a folder instead of losing them.
-c compares by checksum instead of size and time: slower, more certain.
--modify-window=2 treats times up to 2 seconds apart as equal, useful on exFAT and FAT32 drives. See why files copy again.
-E copies extended attributes.
--exclude skips names such as .DS_Store.

The trailing slash

rsync -a ~/Projects /Volumes/Backup/ makes /Volumes/Backup/Projects. rsync -a ~/Projects/ /Volumes/Backup/ copies the contents of Projects straight into Backup. Mixing these up with --delete can delete a lot, which is why the dry run comes first.

Where rsync stops

Two-way sync: rsync copies one way.
A missing drive: if /Volumes/Backup is not mounted, rsync can create it as a folder on your Mac’s disk and fill it. Check that the drive is there in your script.
Scheduling: you add launchd or cron yourself.
iCloud files that are not downloaded: a file that is only in iCloud may be fetched or skipped; test it on a small folder.
Reporting: you read terminal output, or write a log file.

With Pairfold

Pairfold has its own copy engine, not rsync. It shows the preview as a list of New, Changed, To archive and Conflicts, moves replaced and removed files to an archive folder, copies under a temporary name and verifies, can check every copy by checksum, and keeps file dates, tags and extended attributes. A missing disk stops the run. Files only in iCloud are listed as left alone and are not downloaded in bulk.

Limits: it is an app, not a command line; no scripting in version 1; pairs of folders only; macOS 26 or later.

Steps with Pairfold

Click New Pair and choose the source and the destination.
Choose Mirror for the same effect as rsync with --delete, but with an archive.
Click Check and Preview, which is the dry run.
Click Sync.

Get Pairfold: see the app page for where to get it

Questions

Is rsync on Mac safe? It does exactly what you type. With --delete and a wrong slash it can remove files from the destination. Use -n first.

Why does rsync copy everything again? Usually the file times differ by a little (exFAT, FAT32, a NAS) or the drive was not mounted. Try --modify-window=2 and check the destination path.

Can rsync keep deleted files? Yes, with --backup and --backup-dir.

Apple, Mac, macOS, Finder, Time Machine and iCloud are trademarks of Apple Inc. Pairfold is made by Kayabyte and is not affiliated with or endorsed by Apple.