Another rule:

$ echo 'default rule "MARCELLUS" --> black on blue line' >> ~/.clogrc

This rule says that if the text "MARCELLUS" is found, then the matching line is
colored with a blue background.

$ clog < hamlet
FRANCISCO at his post. Enter to him BERNARDO
BERNARDO Whos there?
FRANCISCO Nay, answer me: stand, and unfold yourself.
BERNARDO Long live the king.
FRANCISCO Bernardo?
BERNARDO He.
FRANCISCO You come most carefully upon your hour.
BERNARDO Tis now struck twelve, get thee to bed, Francisco.
FRANCISCO For this relief much thanks: tis bitter cold, And I am sick at heart.
BERNARDO Have you had quiet guard?
FRANCISCO Not a mouse stirring.
BERNARDO Well, good night.  If you do meet Horatio and Marcellus, The rivals of my watch, bid them make haste.
FRANCISCO I think I hear them. Stand, ho. Whos there?
[31mHORATIO[0m Friends to this ground.
[30;44mMARCELLUS And liegemen to the Dane.[0m
FRANCISCO Give you good night.
[30;44mMARCELLUS O, farewell, honest soldier: Who hath relieved you?[0m
FRANCISCO Bernardo has my place.  Give you good night.
[30;44mMARCELLUS Holla. Bernardo.[0m
BERNARDO Say, What, is Horatio there?
[31mHORATIO[0m A piece of him.

