11.15 Changing C Shell History Characters with histchars

The existence of special characters (particularly !) can be a pain; you may often need to type commands that have exclamation points in them, and occasionally need commands with carets (^). These get the C shell confused unless you "quote" them properly. If you use these special characters often, you can choose different ones by setting the histchars variable. histchars is a two-character string; the first character replaces the exclamation point (the "history" character), and the second character replaces the caret (the "modification" character (11.5)). For example:

% set histchars='@#'
% ls file*
file1   file2   file3
% @@   Repeat previous command (was !!)
ls file*
file1   file2   file3
% #file#data#   Edit previous command (was ^file^data^)
ls data*
data4   data5

An obvious point: you can set histchars to any characters you like, but it's a good idea to choose characters that you aren't likely to use often on command lines. Two good choices might be # (hash mark) and , (comma). [2]

[2] In the C shell, # is a comment character (44.2) only in non-interactive shells. Using it as a history character doesn't conflict because history isn't enabled in non-interactive shells.