What is rsync?
Another essential tool for copying data between different hosts is rsync, which stands for remote synchronization. While similar to scp, rsync has a key difference that makes it incredibly efficient. It uses a delta-transfer algorithm that intelligently checks the destination for existing data and only transfers the parts of files that have changed.
For instance, if a large file transfer is interrupted, rsync can resume the copy, transferring only the remaining parts of the file instead of starting over from scratch. This makes it a robust choice for unstable network connections.
Key Features of rsync
The efficiency of rsync comes from its smart optimizations. It verifies file integrity using checksums to ensure the copied data is not corrupted during transfer. These features provide significant flexibility, making rsync an ideal tool for:
- Directory synchronization (both remote and local)
- Creating incremental data backups
- Handling large data transfers efficiently
Common rsync Options
You can modify the behavior of the rsync command with several options. Some of the most commonly used ones include:
-v: Verbose output, showing which files are being transferred.-r: Recursive, which is necessary for copying entire directories.-h: Human-readable output, displaying numbers in a more understandable format (e.g., KB, MB).-z: Compresses file data during the transfer, which is great for slow connections.-a: Archive mode, a convenient shortcut that combines several options (-rlptgoD) to preserve permissions, ownership, and timestamps.
rsync Usage Examples
Sync Files on the Same Host
You can use rsync to synchronize two directories on your local machine. This is useful for creating local backups.
rsync -avh /my/local/directory/one/ /my/local/directory/two/Sync Files from a Remote Host to a Local Host
To pull files from a remote server to your local machine, specify the remote source first.
rsync -avh username@remotehost.com:/remote/directory/ /local/directory/Sync Files from a Local Host to a Remote Host
To push files from your local machine to a remote server, specify the local source first.
rsync -avh /local/directory/ username@remotehost.com:/remote/directory/