simple script to color matching lines (like grep --color, but also prints non-matching lines)

crep

#!/bin/bash

pname="$(basename $0)"
function usage()
{
    echo "Usage: $pname [OPTIONS] PATTERN [FILES and/or GREP_OPTIONS...]

Colorize all matches for PATTERN, an extended regular expression.
Non-matching lines are still printed.

This is a wrapper over grep -E.  See grep(1) for details of extended
regular expression syntax.  The mandatory argument PATTERN acts as
a separator; everything after it is passed to grep as-is.

Examples:
  my_command | $pname my_pattern
  my_command | $pname -c red pattern1 | $pname -c green pattern2
  $pname -c4 -u -b my_pattern my_file -i

Options:

  -b: match is printed bold/bright
  -u: match is underlined
  -b: match blinks
  -i: match is printed in inverse color
  -c [ANSICOLOR]: match is printed in the given foreground color
  -g [ANSICOLOR]: match is printed in the given background color
  -d: prints resulting grep command (for debugging)

ANSICOLOR can be numeric or a color name; valid values are:
  0       1       2       3       4       5       6       7
  black   red     green   yellow  blue    magenta cyan    white
Notice that some colors change hues when bold/bright.
"
    exit
}

sgr=''
debug=''
while getopts 'bulic:g:dh' option; do
    case $option in
        # bold/bright
        b) sgr="$sgr;1";;

        # underline
        u) sgr="$sgr;4";;

        # blink
        l) sgr="$sgr;l";;

        # inverse
        i) sgr="$sgr;7";;

        # foreground color
        c)
            case "$OPTARG" in
                0|black) sgr="$sgr;30";;
                1|red) sgr="$sgr;31";;
                2|green) sgr="$sgr;32" ;;
                3|yellow) sgr="$sgr;33" ;;
                4|blue) sgr="$sgr;34" ;;
                5|magenta) sgr="$sgr;35" ;;
                6|cyan) sgr="$sgr;36" ;;
                7|white) sgr="$sgr;37" ;;
            esac
            ;;

        # background color
        g)
            case "$OPTARG" in
                0|black) sgr="$sgr;40";;
                1|red) sgr="$sgr;41";;
                2|green) sgr="$sgr;42" ;;
                3|yellow) sgr="$sgr;43" ;;
                4|blue) sgr="$sgr;44" ;;
                5|magenta) sgr="$sgr;45" ;;
                6|cyan) sgr="$sgr;46" ;;
                7|white) sgr="$sgr;47" ;;
            esac
            ;;

        d) debug=1;;

        h|*) usage;;
    esac
done

if [ "$sgr" ]; then
    # remove first spurious ';'
    sgr="${sgr:1}"

    # default as of GNU grep 2.6.3, but changing ms= and mc= .
    # see man grep for details.
    export GREP_COLORS="ms=$sgr:mc=$sgr:sl=:cx=:fn=35:ln=32:bn=32:se=36"
fi

shift $((OPTIND-1))

if ! [ "$1" ]; then
    echo "Error: PATTERN argument is mandatory."
    echo
    usage
fi

# "|$" grep trick as described in
# http://stackoverflow.com/questions/981601/colorized-grep-viewing-the-entire-file-with-highlighting
pattern="$1|$"
shift 1

[ $debug ] && set -x

grep -E --color=yes "$pattern" "$@"