[dap]

Good point, and it makes me even more convinced that all rules of thumb have important exceptions. In fact, I've also used tools that use ANSI colorization, and disable that when not talking to a tty, and wished that they wouldn't because I was piping them to "less -R" :) (At least that's a graceful failure mode, and it's pretty clear what probably happened even if one doesn't exactly understand the details.)

[burke]

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, so you could do "uses_colours | ttycat | less -R".

I'm sure it's possible, but you'd have to acquire a new pty and decide what termios settings you want. It's a nontrivial hack, I think.

I'm actually kind of surprised it's not in moreutils[1].

[1]: https://joeyh.name/code/moreutils/

EDIT: Hmm, maybe it's not possible. I can't figure out exactly how to do it, anyway.

EDIT again: Apparently `script` does this on Linux: http://monosnap.com/image/Qlig4CHmQgV9pxvSmndVUgMTU88Adz

EDIT again: Expect's `unbuffer` also does it: http://expect.sourceforge.net/example/unbuffer.man.html#toc

[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"

[dnlrn]

It’s not possible in the way you think, because the two programs don’t know about each other. All the pipe character does is put the stdout into the stdin of the other program.

So this feature must actually be present in the shell and maybe it is. I’m no expert but maybe zsh already offers something like this?