If you haven't GNU grep available, here is something more portable:

    grepc()
    {
      pattern=$1
      shift
      sed 's"'"$pattern"'"^[[32m&^[[0m"g' "$@"
    }

You can customize the color using one of these codes


    30	black
    31	red
    32	green
    33	yellow
    34	blue
    35	magenta
    36	cyan
    37	white

Using `7` instead of a color code will put the string in reverse video.