There's no rc file for grep, but you can set the environment variable
GREP_OPTIONS to a whitespace-separated list of options that will apply to all grep commands. This requires GNU grep (the implementation on non-embedded Linux, Cygwin and some other systems) 2.4; the
--exclude option is new to GNU grep 2.5. Put something like this in your
export GREP_OPTIONS='--color=auto --exclude=*.pyc --exclude-dir=.git'
If you've done this but want to run grep once without those default options, you can override them (e.g.
grep --color=never to force colors off) or empty the
GREP_OPTIONS variable by running
GREP_OPTIONS= grep ….
Another possibility is to define aliases for grep. I use a variant of the following:
alias regrep='grep -Er --exclude=*~ --exclude=*.pyc --exclude-dir=.bzr --exclude-dir=.git --exclude-dir=.svn'