Shallow Thoughts

Configuring git colors

I spent a morning wrestling with git after writing a minor GIMP fix that I wanted to check in. Deceptively simple ideas, like "Check the git log to see the expected format of check-in messages", turned out to be easier said than done.

Part of the problem was git's default colors: colors calculated to be invisible to anyone using a terminal with dark text on a light background. And that sent me down the perilous path of git configuration.

git-config does have a manual page. But it lacks detail: you can't get from there to knowing what to change so that the first line of commits in git log doesn't show up yellow.

But that's okay, thought I: all I need to do is list the default settings, then change anything that's a light color like yellow to a darker color. Easy, right?

Well, no. It turns out there's no way to get the default settings -- because they aren't part of git's config; they're hardwired into the C code.

But you can find most of them with a seach for GIT_COLOR in the source. The most useful lines are these the ones in diff.c, builtin-branch.c and wt-status.c.

gitconfig

The next step is to translate those C lines to git preferences, something you can put in a .gitconfig. Here's a list of all the colors mentioned in the man page, and their default values -- I used "normal" for grep and interactive where I wasn't sure of the defaults.

[color "diff"]
	plain = normal
	meta = bold
	frag = cyan
	old = red
	new = green
	commit = yellow
	whitespace = normal red
[color "branch"]
	current = green
	local = normal
	remote = red
	plain = normal
[color "status"]
	header = normal
	added = red
	updated = green
	changed = red
	untracked = red
	nobranch = red
[color "grep"]
	match = normal
[color "interactive"]
	prompt = normal
	header = normal
	help = normal
	error = normal

The syntax and colors are fairly clearly explained in the manual: allowable colors are normal, black, red, green, yellow, blue, magenta, cyan and white. After the foreground color, you can optionally list a background color. You can also list an attribute, chosen from bold, dim, ul, blink and reverse -- only one at a time, no combining of attributes.

So if you really wanted to, you could say something like

[color "status"]
	header = normal blink
	added = magenta yellow
	updated = green reverse
	changed = red bold
	untracked = blue white
	nobranch = red white bold

Minimal changes for light backgrounds

What's the minimum you need to get everything readable? On the light grey background I use, I needed to change the yellow, cyan and green entries:

[color "diff"]
	frag = cyan
	new = green
	commit = yellow
[color "branch"]
	current = green
[color "status"]
	updated = green

Disclaimer: I haven't tested all these settings -- because I haven't yet figured out where all of them apply. That's another area where the manual is a bit short on detail ...

Tags: git, programming, color
[ 22:26 Feb 02, 2010    More programming | permalink to this entry ]

Vim tip: fixing the light-background color schemes

I use a light background for my X terminals (xterm and rxvt): not white, but a light grey that I find easy on the eyes. Long ago, I spent the time to set up a custom vim color scheme that works with the light background.

But sometimes I need to run vim somewhere where I don't have access to my custom scheme. It always starts up with a lot of the words displayed in yellow, completely unreadable against a light background. :set background=light doesn't help -- the default colorscheme is already intended for a light background, yet it still uses yellow characters.

I tried all the colorschemes installed with ubuntu's vim (you can get a list of them with ls /usr/share/vim/vim71/colors). The only light-background vim schemes that don't use yellow all have their primary text color as red. Do a lot of people really want to edit red text? Maybe the same people who think that yellow is a dark color?

Curiously, it turns out that if you use one of these light color schemes on a Linux console (with its black background), the yellow text isn't yellow (which would show up fine against black), but orange (which would be better on a light background).

Mikael knew the answer:

:set t_Co=88

This tells vim to use 88-color mode instead of its default of 8, and the yellow text turns light blue. Not terrifically readable but much better than yellow. Or, instead, try

:set t_Co=256

and the yellow/light blue text turns an ugly, but readable, orange (probably the same orange as the console used).

So, vim users with dark-on-light terminal schemes: add set t_Co=256 in your .vimrc (no colon) and you'll be much happier.

Update: Pádraig Brady has a great page explaining more about terminal colour highlights, including a TERM=xterm-256color setting to get vim to use 256 colors automatically. There's also a lot of good advice there on enabling colors in other console apps.

The only catch: on Ubuntu you do have to install the ncurses-term package, which will get you xterm-256color as well as 256color variants for lots of other terminal types. Here's useful page on 256-Color XTerms in Ubuntu.

Tags: editors, vim, color, tips
[ 21:29 Mar 22, 2009    More linux/editors | permalink to this entry ]

Helpful Vim Tip: Finding Syntax for Colors

An upgrade from woody to sarge introduced a new problem with editing mail messages in vim: Subject lines appeared in yellow, against my light grey background, so they weren't readable any more.

Vim color files have always been a mystery to me. I have one which I adapted from one of the standard color schemes, but I've never been clear what the legal identifiers are or how to find out. But I changed both places where it said "ctermfg=Yellow" to another color, and nothing changed, so this time I had to find out.

Fortunately a nice person on #vim suggested :he synID (he is short for "help", of course) which told me all I needed to know. Put the cursor on the errant line and type: :echo synIDattr(synID(line("."), col("."), 1), "name")

That told me that the Subject line was syntax class "mailSubject". So I tried (copying other lines in my color file) adding this line:

hi mailSubject term=underline ctermfg=Red guifg=Red

and now all is happy again in vim land. I wish I'd learned that synID trick a long time ago!

Tags: vim, color, editors, tips
[ 09:59 Jun 22, 2005    More linux/editors | permalink to this entry ]