Replace scp with rsync: Reliable File Transfers and Resume Support

What Is rsync?

Rsync is a fast, highly flexible file‑copy tool that works locally, over any remote shell (such as SSH), or via a dedicated rsync daemon. It uses an incremental transfer algorithm that sends only the differences between source and destination files, dramatically reducing network traffic. The default "quick‑check" algorithm compares file size and modification time to decide what needs updating.

Supported Platforms

Rsync runs on any Unix‑like system, including Linux and macOS. There are also ports for Windows, though they are less common.

Installation

On Debian‑based distributions (Ubuntu, etc.) use: sudo apt install rsync On RedHat‑based systems (RHEL, CentOS, Fedora) use: sudo yum install rsync On macOS with Homebrew: brew install rsync Verify the installation with:

rsync --version

Basic Usage

Copy a file from the local host to a remote host (similar to scp) while adding useful options:

rsync -partial -z -e 'ssh -p 22' linuxmi.cpp [email protected]:/home/linuxmi

Explanation of the options: -e 'ssh -p 22' – Use SSH on port 22 for the connection. -z – Compress data during transfer to speed up the copy. -partial – Keep partially transferred files so that an interrupted transfer can be resumed. Without this flag, rsync deletes incomplete files.

Resuming Interrupted Transfers

If a transfer is stopped after using -partial, simply re‑run the same command. Rsync will detect the existing partial file and continue copying from where it left off, effectively “magically” resuming the transfer.

Conclusion

Rsync offers many powerful options beyond basic copying, such as bandwidth limiting, exclusion patterns, and more. The most critical feature for reliable transfers is the ability to resume interrupted copies using -partial. Use the commands above to replace scp with rsync for safer, faster file synchronization.