[JdeBP]

> I've always thought it would be nice to have a utility like cat that I could pipe commands to, which would trick them into thinking all their streams were attached to a tty,

Daniel J. Bernstein wrote a "pty" package back around 1991 that did this. Version 4 of the package was published in 1992 to comp.sources.unix (volume 25 issues 127 to 135). It's still locatable on the World Wide Web.

Bernstein later updated this, around 1999, with a "ptyget" package that was more modular and that had the session management commands moved out of the toolset to elsewhere. The command from that package to do exactly what you describe is "ptybandage". There is also "ptyrun". Paul Jarc still publishes a fixed version of ptyget (that attempts to deal with the operating-system-specific pseudo-terminal device ioctls in the original) at http://code.dogmap.org./ptyget/ .

As a bonus feature for people who use source code, there are similar "ptybandage" and "ptyrun" scripts, for which you will need Laurent Bercot's execline tool (http://skarnet.org./software/execline/), in the source archive for the nosh package at http://homepage.ntlworld.com./jonathan.deboynepollard/Softwa... . These make use of the terminal-management tools in the nosh toolset.

With both of these, you should be able to run "ptybandage uses_colours_if_tty | less -R"