I want to quickly create a backup of a file, by creating a duplicate with a '~' at the end, in terminal. Is there any straight forward single command way of doing this?
Create a shell function
Put it in your shell rc file, for bash it is ~/.bashrc. Source .bashrc or start a new shell.
And you have a copy of yourFile.
Rsync works Great for backup. It is mostly used for server backup.
Here You can defines source and destination. source may be file or directly on local or Remote server/machine.