11.16 Instead of Changing History Characters

If you need to use ! (or your current history character) for a command (most often, a uucp or mail (1.33 ) command), you can type a backslash (\ ) before each history character. You can also drop into the Bourne shell quickly (assuming that you aren't on a system that has replaced the real Bourne shell with bash ). Either of these are probably easier than changing histchars . For example:

% mail ora\!ishtar\!sally < file1

Quote the !s

% sh   

Start the Bourne shell

$ mail ora!ishtar!sally < file1

! not special here

$ exit   

Quit the Bourne shell

%   And back to the C shell

The original Bourne shell doesn't have any kind of history substitution, so ! doesn't mean anything special; it's just a regular character.

By the way, if you have a window system, you can probably copy and paste the command line instead of using shell history.