git-diff console default colors meanings-CodePudding

I'm now a little lost on the meanings of various colors in the default color scheme of git-diff in the console. I can't seem to find any documentation on them. I'm using xfce4-terminal in Manjaro/XFCE.

It looks like the default color scheme for git-diff is "zebra". I have eight import statements shown in my diff represented in seven different colors. That seems a little crazy to me.

Thank you.

CodePudding user response：

TL;DR

You probably have diff.colorMoved set in your Git configuration (run git config --get diff.colorMoved; to see who's setting it, use git config --list --show-origin). The default if this mode is requested is indeed zebra, which apparently calls to your mind the same thing it does to mine: Angry Fruit Salad.

Long

Back in the Dim Time, there was no color. We were grateful for the Glass TTY that replaced our old printers. Plain diff was invented and it had three things it mentioned:

added lines, signified by a;
deleted lines, signified by d; and
changed lines, signified by c.

For instance:

$ cat old
$ cat old
line one
line two
line three
line four
line five
$ cat new
line one
inserted
line two
line four
line 5
$ diff old new
1a2
> inserted
3d3
< line three
5c5
< line five
---
> line 5

Later, context diff was invented as a more useful way to show this:

$ diff -c old new
*** old 2021-09-13 16:11:48.145950000 -0700
--- new 2021-09-13 16:11:56.597068000 -0700
***************
*** 1,5 ****
  line one
  line two
- line three
  line four
! line five
--- 1,5 ----
  line one
  inserted
  line two
  line four
! line 5

The marker letters a, d, and c are replaced with front-of-line markers , -, and ! respectively.

Of course, "changed" just means "deleted and added". In unified mode, plain diff uses these instead, so there's no ! any more:

$ diff -u old new
--- old 2021-09-13 16:11:48.145950000 -0700
    new 2021-09-13 16:11:56.597068000 -0700
@@ -1,5  1,5 @@
 line one
 inserted
 line two
-line three
 line four
-line five
 line 5

I'll skip over the precise difference between "context" and "unified" diff since it's not that interesting, but both provide context. "Unified" usually makes the output smaller and easier for humans to read, at the cost of making it slightly harder to machine-parse.

Colo(u)r and Git

Eventually, our black-and-white displays gave way to color, windowing, and all the other fanciness. Naturally, someone added colors to diff output: red for removed text, and green for added text, quite commonly. This was no doubt chosen because the most common form of color-blindness is red-green. So, along comes git diff, which uses these colors to ditch the left column ("gutter") insertion to get rid of the spaces and and - markers ... oh, wait, it doesn't:

$ git diff old new
diff --git a/old b/new
index 9864d22..8e331db 100644
--- a/old
    b/new
@@ -1,5  1,5 @@
 line one
 inserted
 line two
-line three
 line four
-line five
 line 5

This fixes the color blindness issue, right?