Add environment variable to control colored output

[inferrna]

There is such possibility https://docs.rs/clap/latest/clap/enum.ColorChoice.html#variant.Always but it requires code modification. So, it would be nice to control this behavior with clap-specific environment variable.

For example
Inside app just

let args = Args::parse()

then, when it needed

CLAP_ALWAYS_COLORED=1 ./myapp | ansi2html > pretty_doc.html

[epage]

Is there a reason you want a clap-specific env variable?

As part of the color work we will be doing soon, I was planning to support

• CLICOLOR, FORCE_CLICOLOR, https://bixense.com/clicolors/
• NO_COLOR, https://no-color.org/

[inferrna]

FORCE_CLICOLOR or CLICOLOR_FORCE would be great, thank you. Is there a tracking issue for this feature?

[epage]

Doesn't look like it; feel free to create one.

[epage]

#4765 will address this