Instant replay

Rather than viewing or grepping through your history file for a previously executed command, try tapping Ctrl+R. The shell will prompt you to type in a string, at which point you can type in the first few letters of an eariler command. Enter a couple of characters and the shell will show you the first command it finds in history that match that string. If the command displayed is close-but-no-cigar, type a few more characters to fine-tune the search. When the correct command is displayed, hit Enter to execute it.