# Defining command \old| [duplicate]

I want to let the command \old| refer to the command \| (which produces the output ||.) So I do:

\let\old|\|


LaTeX complains "Missing \$ inserted." How can I fix it?

## marked as duplicate by yo', Marco Daniel, Mensch, Stefan Kottwitz♦Mar 2 '13 at 22:05

• Use \def\old#1{\|} and than you can work with \old| – Marco Daniel Mar 2 '13 at 20:01
• A command name is (in default setting) either \<one-char> or \<arbitrary-number-of-letters>. The character | is not a letter. I suggest using \let\oldvert\| . – yo' Mar 2 '13 at 20:04