Using csh & tcsh

Using Commands from Your History

Use the ! character to begin a reference to an event in the history list. The shell sees the !, determines from the characters following it which event you want to use, performs a history substitution on the command line, and then executes the command. To keep you informed, the shell echoes the resulting command before executing it. Here's a simple example using !!, the "repeat previous command" operator:

% date                            Type a command
Tue Mar  7 13:01:25 CST 1995      Output from the command
% !!                              Repeat the command
date                              Shell shows the resulting command
Tue Mar  7 13:01:32 CST 1995      Output from the command

The full syntax for a history reference looks like this:

!event:words:modifiers

That's a mouthful, but most of it is optional. In practice, history references tend to be simple, such as !! to repeat the previous command or !$ to repeat its last argument. Here's what the parts of a history reference mean:

event	The event (command) you want to refer to.
words	Which words to select from the command. words is optional; if missing, the entire command is selected.
modifiers	How to modify the selected event or words. modifiers is optional; if missing, the event or words are recalled without change.

The following sections describe the parts of history references in more detail.