Respect NO_COLOR environment variable

[Seirdy]

• [X] I have read through the manual page (man fzf)
• [X] I have the latest version of fzf
• [X] I have searched through the existing issues

Info

• OS
  • [X] Linux
  • [ ] Mac OS X
  • [ ] Windows
  • [ ] Etc.
• Shell
  • [X] bash
  • [X] zsh
  • [ ] fish

Problem / Steps to reproduce

Running fzf with the NO_COLOR environment variable should disable ANSI color output as described by no-color.org.

[LuRsT]

@Seirdy, fzf is listed on that website with a way to have colors disabled:

From the man page:

       --color=[BASE_SCHEME][,COLOR:ANSI]
              Color configuration. The name of the base color scheme is followed by custom color mappings. Ansi color code of -1 denotes terminal default foreground/background color.  You  can  also  specify
                  (...)
                  bw      No colors (equivalent to --no-color)

Isn't this enough for your use case?

[Seirdy]

@LuRsT I am aware that it is possible to use this option and to make it the default by including it in $FZF_DEFAULT_OPTS; however, this doesn't address the problem outlined at https://no-color.org:

Unfortunately, every new piece of software seems to have a different way of disabling colored text

I believe that FZF shouldn't require this additional configuration if the $NO_COLOR environment variable is set. Following this standard will reduce the burden of looking up how each CLI tool disables color output.

[LuRsT]

I guess that'd be @junegunn 's call. What do you think?

[junegunn]

It is not clear to me that the protocol is, and will be, widely agreed upon. The linked page shows that only a small number of tools, most of them I've never heard of, decided to have implemented it. There is even a competing standard that has existed over the years. I've also noticed there are some projects implementing FORCE_COLOR instead of or along with NO_COLOR.

For now, I don't see a compelling reason for fzf to implement the protocol. I'd like to revisit this after NO_COLOR has garnered wide adoption.

[Seirdy]

Currently, the NO_COLOR standard seems to be more popular; it is accepted by popular software such as NPM, Homebrew, Gatsby, Symfony, and Elixir.

Furthermore, these standards aren't mutually exclusive; all that's necessary is an order of precedence. That being said, I understand if this issue needs to be put on hold until one standard receives wider adoption.