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Where is the format of git log --oneline --decorate defined?

Using git Iog --format=format:'my format', I cannot reproduce the colours of the branches, tags and HEAD as shown by git log --oneline --decorate.

 git log --oneline --decorate

shows HEAD in light blue, the branch names in green and the punctuations (,,) in brown.

The closest I have come to getting what I want is: 

git log --graph --abbrev-commit --decorate --date=short --format=format:'%C(bold blue)%h%C(reset) %C(bold green)%ad%C(reset)%d %C(white)%s%C(reset)' -20

with the only difference being that the branches/HEAD/tags are not coloured like with the previous command.

augustin
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2 Answers2

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It does not appear to be possible with git version < 1.8.3.

Since git 1.8.3, one could use the colour %C(auto) token: 

   git log --graph --decorate --date=short --format='%C(bold blue)%h%C %C(bold green)%ad %C(auto)%d  %C(white)%s%C(reset)' -10

The key element being: 

%C(auto)%d ...  %C(reset)

See also:

Color in git-log
Git pretty format colors

augustin
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  • Instead of `%d` you may want to use `%D` for some use cases but `%d` does match the `--oneline --decorate` rendering. Also note that `%Creset` does also work but `%Cauto` does not work and one must use `%C(auto)` for nice colors. Also, you may often want `tformat` instead of `format`. – Mikko Rantalainen Nov 05 '18 at 10:23
  • @MikkoRantalainen, you are correct about `tformat`. There is a shorthand `--format=xxx` for `--format=tformat:xxx`, but I do not really know when it was introduced, and the answer as it stands is backward-compatible to 1.8.3, so I'm reluctant to edit it. `--abbrev-commit` seems superfluous, even probably for 1.8.3, however, because `%h` already stands for the abbreviated form. I'll leave both point to augustin to decide. The third one is that `%C(reset)` is excessive right before the next `%C…`. It's a very helpful answer, even in its current form. – kkm inactive - support strike Dec 13 '19 at 01:37
  • @kkm I edited the answer as per your suggestions. Thanks. – augustin Dec 21 '19 at 03:10
3

TL;DR - I don't think it's possible for you to get the exact format that git log --oneline provides because the --format option doesn't allow any conditional statements, while git-log is using a function to generate that string on a per commit message.

The closest I got with the colors is this:

git log --format=format:'%C(auto)%h%C(reset) %C(auto)%s%C(reset)'

Looks like this on my machine:

terminal-screenshot

Long version:

The most documentation you can read on git-log is here: https://git-scm.com/docs/git-log

I delved into the source (available on github here) to see what exactly git does for the --oneline option, here's what I found:

  • The trail starts here in revision.c, where the command line options are parsed

  • The option is then parsed in pretty.c to match CMIT_FMT_ONELINE of the cmit_fmt enum (defined in commit.h)

  • Finally, the actual printing happens over in pretty.c at pp_commit_easy.

  • This is where it gets tricky and complicated. You can see references to CMIT_FMT_ONELINE in a handful of places in pretty.c. I believe that only pp_title_line is executed for each commit when the --oneline option is specified. You can see that there's a bunch of conditional formatting going on as the string buffer is constructed.

So yeah, I don't think there's a way to replicate the actual format with the tags and (HEAD -> master) meta information. You can probably write a shell script that does the same, but its performance may not match up to that of git's.

Vidur
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