Rsync
Contents
rsync
rsync (remote sync) is a fast, versatile, and widely-used command-line utility for synchronizing and transferring files and directories between two locations, either on the same system or across a network. It minimizes data transfer by only copying the differences (deltas) between source and destination files using an efficient algorithm.
Originally developed by Andrew Tridgell and Paul Mackerras, `rsync` is included by default on most Unix-like operating systems, including Linux, macOS, and BSD.
Key Features
- **Delta transfer algorithm** – Only changes within files are sent
- **Compression and encryption** – Optional `--compress` and SSH support
- **Preserves metadata** – File permissions, timestamps, ownership, symbolic links, and more
- **Supports local and remote sync** – Works on the same machine or across SSH
- **Progress and dry-run support** – Track transfers and test without making changes
- **Efficient backups** – Ideal for incremental or automated backups
Basic Syntax
<syntaxhighlight lang="bash"> rsync [options] [source] [destination] </syntaxhighlight>
Common Examples
Copy a local folder to another local directory:
<syntaxhighlight lang="bash"> rsync -av /source/ /destination/ </syntaxhighlight>
Copy a folder to a remote server using SSH:
<syntaxhighlight lang="bash"> rsync -avz /local/folder/ user@remote_host:/remote/folder/ </syntaxhighlight>
Sync from a remote server to local:
<syntaxhighlight lang="bash"> rsync -avz user@remote_host:/remote/folder/ /local/folder/ </syntaxhighlight>
Show progress during transfer:
<syntaxhighlight lang="bash"> rsync -avz --progress /source/ /destination/ </syntaxhighlight>
Dry-run (test run without actual copying):
<syntaxhighlight lang="bash"> rsync -avz --dry-run /source/ /destination/ </syntaxhighlight>
Key Options
| Option | Description |
|---|---|
| `-a` | Archive mode (recursive, preserve permissions, timestamps, etc.) |
| `-v` | Verbose output |
| `-z` | Compress file data during transfer |
| `-e ssh` | Use SSH for remote shell |
| `--progress` | Show progress of each file |
| `--delete` | Delete files in destination that no longer exist in source |
| `--dry-run` | Show what would be done without making changes |
Use Cases
- Syncing files to a seedbox or VPS
- Backing up local or remote directories
- Deploying web content to a server
- Cloning directories with minimal data usage
- Scheduling automated backups via `cron`
rsync vs Other Tools
| Feature | rsync | scp | sftp |
|---|---|---|---|
| Delta transfers | Yes | No | No |
| Directory sync | Yes | Partial | Partial |
| Compression | Yes | Yes | Yes |
| Metadata preservation | Full | Basic | Moderate |
| Interactive interface | No | No | Yes |
| Use over SSH | Yes | Yes | Yes |
Integration with Automation
`rsync` is commonly used in automated scripts and backup systems:
- Cron jobs (`crontab -e`)
- Systemd timers
- Remote mirroring
- Snapshot backups (e.g., with hard links)
Security
- Uses SSH for encrypted transfers when specified (`-e ssh`)
- Supports public key authentication
- Minimizes attack surface by requiring only basic SSH setup
Installation
On Debian/Ubuntu:
<syntaxhighlight lang="bash"> sudo apt update sudo apt install rsync </syntaxhighlight>
Related Tools and Enhancements
- Grsync – GUI frontend for rsync
- Rclone – Cloud-oriented alternative with rsync-like syntax
- Duplicity – Backup tool using rsync concepts with encryption
- Syncthing – Real-time file sync alternative with a GUI
