Re: [PATCH iproute2-next v2] color: default to dark color theme

[Phil Sutter <phil@nwl.cc>]

On Mon, Mar 10, 2025 at 02:12:16PM -0700, Stephen Hemminger wrote:
> On Mon, 10 Mar 2025 21:36:09 +0100
> Matteo Croce <technoboy85@gmail.com> wrote:
> 
> > From: Matteo Croce <teknoraver@meta.com>
> > 
> > The majority of Linux terminals are using a dark background.
> > iproute2 tries to detect the color theme via the `COLORFGBG` environment
> > variable, and defaults to light background if not set.
> >
> 
> This is not true. The default gnome terminal color palette is not dark.

ACK. Ever since that famous movie I stick to the real(TM) programmer
colors of green on black[1], but about half of all the blue pill takers
probably don't.

> > Change the default behaviour to dark background, and while at it change
> > the current logic which assumes that the color code is a single digit.
> > 
> > Signed-off-by: Matteo Croce <teknoraver@meta.com>
> 
> The code was added to follow the conventions of other Linux packages.
> Probably best to do something smarter (like util-linux) or more exactly
> follow what systemd or vim are doing.

I can't recall a single system on which I didn't have to 'set bg=dark'
in .vimrc explicitly, so this makes me curious: Could you name a
concrete example of working auto color adjustment to given terminal
background?

Looking at vim-9.1.0794 source code, I see:

|     char_u *
| term_bg_default(void)
| {
| #if defined(MSWIN)
|     // DOS console is nearly always black
|     return (char_u *)"dark";
| #else
|     char_u      *p;
| 
|     if (STRCMP(T_NAME, "linux") == 0
|             || STRCMP(T_NAME, "screen.linux") == 0
|             || STRNCMP(T_NAME, "cygwin", 6) == 0
|             || STRNCMP(T_NAME, "putty", 5) == 0
|             || ((p = mch_getenv((char_u *)"COLORFGBG")) != NULL
|                 && (p = vim_strrchr(p, ';')) != NULL
|                 && ((p[1] >= '0' && p[1] <= '6') || p[1] == '8')
|                 && p[2] == NUL))
|         return (char_u *)"dark";
|     return (char_u *)"light";
| #endif
| }

So apart from a little guesswork based on terminal names, this does the
same as iproute currently (in his commit 54eab4c79a608 implementing
set_color_palette(), Petr Vorel even admitted where he had copied the
code from). No hidden gems to be found in vim sources, at least!

Cheers, Phil

[1] And have the screen rotated 90 degrees to make it more realistic,
    but that's off topic.