Passes a text stream from stdin to stdout, adding terminal codes to colorise the output based on regular expressions.

colorise

#!/bin/bash

BLACK=30
GRAY="$BLACK;1"
RED=31
BOLDRED="$RED;1"
GREEN=32
BOLDGREEN="$GREEN;1"
YELLOW=33
BOLDYELLOW="$YELLOW;1"
BLUE=34
BOLDBLUE="$BLUE;1"
PURPLE=35
BOLDPURPLE="$PURPLE;1"
CYAN=36
BOLDCYAN="$CYAN;1"
WHITE=37
BOLDWHITE="$WHITE;1"

USAGE="$0 {REGXP=COLOR}
Passes a text stream from stdin to stdout, adding terminal codes to colorise the output.
Any string matching REGXP will be output as COLOR.
All instances of the '/' character in REGXP must be escaped.
Note that in ambiguous cases like: \"x=.*\"=RED, the LAST = character is considered the seperator.
The following COLORs are supported:
	BLACK  GREY
	RED    BOLDRED
	GREEN  BOLDGREEN
	YELLOW BOLDYELLOW
	BLUE   BOLDBLUE
	PURPLE BOLDPURPLE
	CYAN   BOLDCYAN
	WHITE  BOLDWHITE
Any unrecognised color will be interpreted as a direct SGI escape (the section between CSI and 'm') to substitute in.

Options:
	-v --verbose : Print the generated sed expression before running.
"

SEDEXPR=""
for arg in "$@"; do
	case "$arg" in
		"-v"|"--verbose")
			VERBOSE=true
		;;
		"-h"|"--help")
			echo "$USAGE"
			exit 1
		;;
		*)
			regex=${arg%=*}
			color=${arg##*=}
			color=${!color:-$color}
			SEDEXPR="$SEDEXPR s/$regex/\x1b[${color}m\0\x1b[m/;"
		;;
	esac
done

if [ "$VERBOSE" ]; then
	echo "sed $SEDEXPR"
fi

sed "$SEDEXPR"