Under many versions of UNIX, . provides a mechanism for recalling and re-executing previous commands. The vertical arrow keys on the keyboard can be used to scroll forward and backward through a command history. Once a command is located in this way, the cursor can be moved within the command using the horizontal arrow keys, and characters can be removed with the Delete key or added with the other keys.
The recall and editing capabilities are highly customizable. You can find out how to do this by reading the UNIX manual entry for the readline library.
Alternatively, the emacs text editor provides rather more general support mechanisms for working interactively with ..
The Macintosh and Windows versions of R do not currently have this level of flexibility for recalling previous commands. For these users we recommend storing your commands in a separate file and using your favourite word processor in conjunction with cut and paste to execute the commands in ..