RsyncProject/rsync — reverse-engineered prompt

Build me a fast command line file copying and syncing tool for local folders and remote machines. It should work a lot like scp for simple use, but be smarter when files already exist, so it only sends the parts that changed instead of copying everything again.

I want it to be useful for backups, restores, keeping two folders in sync, and moving large files over slow connections. It should support remote transfers over ssh, plus an optional daemon mode for people who want to share files from a server with access control. Please include clear terminal help, useful error messages, and basic documentation so someone can build, install, and use it without guessing.

Implement it as a solid C project with a normal configure, make, make install flow, and include tests for the core syncing behavior. Look up current docs online if you need to.