How to escape pipe character in `:make`, `:grep` and friends

Question

I'm trying to use :grep to search for one of several words. Since grep accepts regular expressions, I figured I could just use the pipe character | to build a single expression for both words:

:grep -E 'foo|baz' *.c

Vim interprets the | as a separator between two commands. :help :bar suggests that I could escape it as \|, but that doesn't work, either. It seems that the :grep command does not handle backspaces and quotes.

:help map-bar also offers the suggestion to use ^V|, which actually escapes the pipe character, but now the ^V is also in my pattern.

Right now, the only workaround I've found is using environment variables:

:let $BAR = '|' | grep -E 'foo'$BAR'baz' *.c

But this is quite crazy in my opinion. Is there really no better way?

Answer 1

As stated on the question, :h map-bar suggests escaping the pipe with with \|. However, grep apparently understands that as a literal bar, thus the backslash needs to be escaped as well. This should work for grep:

:grep -E 'foo\\|baz' *.c

NOTE: there's no need to escape the backslash with vimgrep (:h :vimgrep). The following seems to give the same results here:

:vimgrep 'foo\|baz' *.c