Instead of Changing History Characters

If you need to use ! (or your current history character) for a command (for example, if you still use uucp or send mail to someone who does, using the command-line mail ( Section 1.21) command), you can type a backslash (\) before each history character. You can also drop into the Bourne or Korn shell quickly — assuming that you aren't on a system that has replaced the real Bourne shell with a shell like bash that has history substitution built in. (If you're stuck, you can use the command set +H in bash; this disables history substitution.) 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 (Section 28.10) instead of using shell history.

— ML