Simple definition
rsync is a file-copying and synchronization tool often used to move data between directories or hosts.
Technical definition
rsync compares source and destination files and transfers changes efficiently. It can preserve metadata, connect through SSH, and optionally remove destination files that no longer exist in the source. Always review the direction of the copy and use --dry-run before destructive options.
What is it used for ?
Synchronize directories, migrate files or create incremental file-level backup copies.
Practical example
For example, rsync -av --dry-run /data/ user@server:/backup/ previews a remote synchronization without changing destination files.
Common issues
- Option –delete used without precaution
- Unpreserved permissions
- Source path with final slash misunderstood
Related terms
SSH
Key takeaway: Exact behavior and commands may vary depending on versions, products and architectures.