Find user login history – last and lastb commands in Linux
last and lastb commands print the user login history. last prints the previous logged in users and lastb shows the failed login attempts.
Synchronizing Files Between Multiple Computers Using Unison
Unison is a file synchronization tool. It synchronizes directory trees on two hosts both ways, so that the files at both ends are the latest.
rsync
rsync is a file synchronization tool for making that the destination files become an exact replica of corresponding files at the source.