Take care what name you give to the file or directory that the file or directory is being moved to.
If you choose the name of a file or directory that already exists it will be replaced by the file or directory that has been moved to its name!
Always use the mv command together with its -i option. This will prompt you for confirmation whenever the moved file or directory would overwrite an existing file or directory.
**The i option is not available with some versions of the command.**
Check the manual page for the mv command on your system.