Re: Highlighting in grep buffer

[Richard Stallman]

    > It needs comments to explain what GREP_COLOR means
    > and what that value means and why.

    According to grep man page, the environment variable GREP_COLOR
    specifies the marker for highlighting, GREP_OPTIONS specifies default
    options to be placed in front of any explicit options, and the option
    --color surrounds the matching string with the marker found in GREP_COLOR
    environment variable.

Ok, please add comments in the Lisp code with that information.
Don't expect people maintaining Emacs to know such obscure
things about GNU grep!

    > It may be less reliable, in that it may not work with non-GNU grep
    > programs.  Perhaps that is ok; people should install GNU grep.

    Even though this feature will not be available for non-GNU greps,
    I can't tell if the GREP_OPTIONS=--colors will cause them to fail.

It could be they will simply not notice.  Could you arrange to test
this on a few recent modern?