Re: Bug#396485: diff & sdiff: please allow full-color output (fwd)

[Matthew Woehlke]

Santiago Vila wrote:
> It would be great if diff and/or sdiff could show their output in color.
>
> ...you could pick the most convenient option for the most users:
> you could show color automatically if stdout is an interactive
> terminal as opposed to a pipe.

Well, I for one like this idea. Given that 'ls' and 'grep' do it, I 
don't think it is unprecedented.

Note some standards (based on 'ls' and 'grep') that should apply:

- The option is '--color[=_when_]', where _when_ is 'yes'/'always', 
'no'/'never', 'tty'/'auto', with 'auto' being default if --color is 
specified and 'no' otherwise. The option '--colour[=_when_]' (in grep, 
but not in ls) may optionally be a synonym.

- The environment variable DIFF_COLOR specifies what colors should be used.

- The correct way to enable color by default is with a system-wide 
alias. This is a distribution decision; when coding, do not consider this.

Alternatively, if this is not suitable for 'diff' itself, it might be an 
excellent candidate for the currently-proposed miscutils project (see 
the coreutils list), since it is relatively easy to do this with the 
help of 'sed'.

--
Matthew
"Inches: An antiquated measurement unit still in use in certain 
backwards countries with incredibly low-cost computer equipment."
  -- groff documentation