What UNIX commands support coloured output?

Why don't you try:

man -K color

That should search for the word color in all your man pages (content, not just headings).

It asks, for each man page, whether you want to open and view the page:

$ man -K color/usr/share/man/mann/Widget.n.gz? [ynq] y/usr/share/man/mann/usual.n.gz? [ynq] y/usr/share/man/mann/Toplevel.n.gz? [ynq] n/usr/share/man/mann/itk.n.gz? [ynq] n/usr/share/man/mann/Archetype.n.gz? [ynq] n/usr/share/man/man8/squid.8.gz? [ynq] n/usr/share/man/man7/Xprint.7.gz? [ynq]/usr/share/man/man7/X.7.gz? [ynq]/usr/share/man/man7/urxvt.7.gz? [ynq]/usr/share/man/man7/term.7.gz? [ynq] q$

Inside each individual man page, you can use your normal search method (e.g., /color<ENTER>) for finding the text. When done with a man page, just exit and it will continue searching.

A quick bit of google search also reveals grc and grcat, which can be used to colorise any arbitrary text or command. Not sure how well they work though. I'm certainly going to try them out now that I've found them.

Ah, here we go. grc uses the /etc/grc.conf file to colorise a given command based on which regexp it matches. A quick grep of my (Ubuntu 8.10) /etc/grc.conf reveals it currently has support for:

[~]$ less /etc/grc.conf | grep '^#'# anything to do with irc# log file# ping command# traceroute command# gcc command# make command# netstat command# diff command# last command# ldap tools# cvs command

But I'm sure you could add your own for other programs you are interested in.

To use grc, simply put it before the command you want to colorise (lets say diff):

grc diff foo.txt bar.txt

And you could certainly alias diff='grc diff' to make diff colorised by default.

I'm quite fond of coloring my prompt so that it stands out. A useful article on that sort of thing is available here.