# Redefine a built-in math command [duplicate]

Possible Duplicate:
Can I redefine a command to contain itself?

I'm trying to redefine the \int command so that it will always do \int \!. So here's my attempt at that:

\renewcommand{\int}{\int \!}


But then I'd get this error:

\! TeX capacity exceeded, sorry [input stack size=5000].
\int ->\int


On the other hand, I looked up \show\int, which got me \intop \nolimits . So I tried to use it in a \renewcommand:

\renewcommand{\int}{\intop \nolimits . foobarbaz}
% The foobarbaz is for testing if the \renewcommand is effective


But no, I don't see foobarbaz in the output.

How do I redefine math commands?

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## marked as duplicate by David Carlisle, Ian Thompson, percusse, Marco Daniel, Loop SpaceApr 26 '12 at 13:03

Make a copy of the old command using \let, then use the copy to create the new command.
\let\oldint\int