Oh, Git Configurations! Let's Simplify It

Oh, Git Is Complex!

Git is a complex system. To see the proof, check out:

1. ohshitgit.com
2. gitfightrules.com

To mitigate that, we are going to get inside the head of Linus Torvalds! (Just a little bit - maybe into a single neuron). In this part, we will focus on configurations. I always thought that to understand a system, I needed to understand its configurations (or even better, its installation).

When I get to a new company, the first thing I try to figure out is:

1. How do I install this?
2. How do I configure this?

How Does Linus Torvalds Think?

"Everything is a file."

Yes, this is how Linus thinks: everything is a file.

As Linus loves this idea that everything is a file, you can just view git configurations as a file.

So, if we manage to learn which files Linus uses in git, we might be able to penetrate oh-my-complex-git!

3 Fallback Layers of Config

1. System - Your OS git config - git config --system
2. Global - Your User git config - git config --global
3. Local - Your Repository git config - git config --local

git config --system # => /etc/gitconfig

git config --glboal # => ~/.gitconfig or ~/.config/git/config

git config --local # => .git/config

Git first reads the git config from .git/config -> [fallback to] ~/.gitfconfig -> [fallback to] /etc/gitconfig.

Email per Repo

If you have different email addresses for different repositories, this goes into .gitconfig == git config --local

Get the Global Config With git config --list --global

➜  tmp git config --list --global

user.name=Tomer Ben David
user.email=tomer.bendavid@ohohoh.com
core.autocrlf=input
format.pretty=format:%h %Cblue%ad%Creset %ae %Cgreen%s%Creset

Would that be the same as cat ~/.gitconfig? What do you think?

➜  tmp cat ~/.gitconfig
[user]
    name = Tomer Ben David
    email = tomer.bendavid@ohohoh.com
[core]
    autocrlf = input
[format]
  pretty = format:%h %Cblue%ad%Creset %ae %Cgreen%s%Creset

Yes and no! It's a different notation, but generally the same!

Get the Merged Config With git config --list

The merged config is the combination of all configs with the hierarchy. Let's see it on my machine:

git config --list

➜  tmp git config --list
core.excludesfile=~/.gitignore
core.legacyheaders=false
core.quotepath=false
mergetool.keepbackup=true
push.default=simple
color.ui=auto
color.interactive=auto
repack.usedeltabaseoffset=true
alias.s=status
alias.a=!git add . && git status
alias.au=!git add -u . && git status
alias.aa=!git add . && git add -u . && git status
alias.c=commit
alias.cm=commit -m
alias.ca=commit --amend
alias.ac=!git add . && git commit
alias.acm=!git add . && git commit -m
alias.l=log --graph --all --pretty=format:'%C(yellow)%h%C(cyan)%d%Creset %s %C(white)- %an, %ar%Creset'
alias.ll=log --stat --abbrev-commit
alias.lg=log --color --graph --pretty=format:'%C(bold white)%h%Creset -%C(bold green)%d%Creset %s %C(bold green)(%cr)%Creset %C(bold blue)<%an>%Creset' --abbrev-commit --date=relative
alias.llg=log --color --graph --pretty=format:'%C(bold white)%H %d%Creset%n%s%n%+b%C(bold blue)%an <%ae>%Creset %C(bold green)%cr (%ci)' --abbrev-commit
alias.d=diff
alias.master=checkout master
alias.spull=svn rebase
alias.spush=svn dcommit
alias.alias=!git config --list | grep 'alias\.' | sed 's/alias\.\([^=]*\)=\(.*\)/\1\     => \2/' | sort
include.path=~/.gitcinclude
include.path=.githubconfig
include.path=.gitcredential
diff.exif.textconv=exif
credential.helper=osxkeychain
user.name=Tomer Ben David
user.email=tomer.bendavid@ohohohoh.com
core.autocrlf=input
format.pretty=format:%h %Cblue%ad%Creset %ae %Cgreen%s%Creset

That was it - all the git config on my machine! I hope I didn't put any passwords in there! If I did please, let me know - code review is important, guys!

Git Config --local/global/system user.name - Get a Single Config

Ask layer by layer for a config:

➜  tmp git config --local user.name
fatal: BUG: setup_git_env called without repository # We called from a non-repository folder.
➜  tmp git config --global user.name
Tomer Ben David
➜  tmp git config --system user.name # => nothing in the global config file.
➜  tmp

Aha! So it's coming from the global (user) config!

Note that in the file, it's with [user] and the name, and the git config returns the combined name user.name.

If you need a hierarchy larger than three, then in the file, it will look like this:

[branch "gke"]
    remote = origin
    merge = refs/heads/gke

So, this one should be branch.gke.remote. Let's verify this:

➜  .git git:(gke) git config branch.gke.remote # => yes it is branch.gke.remote!
origin

Set a New Config With git config mysection.mykey myvalue

➜  .git git:(gke) git config mysection.mykey myvalue
➜  .git git:(gke) git config mysection.mykey
myvalue

So, we were able to set it. Let's look at the file:

➜  .git git:(gke) cat config
[core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true
    ignorecase = true
    precomposeunicode = true
[remote "origin"]
    url = https://bitbucket.org/yshenbaum/k8s-course.git
    fetch = +refs/heads/*:refs/remotes/origin/*
[branch "gke"]
    remote = origin
    merge = refs/heads/gke
[mysection] ##### =====> Here it is! see the section in []
    mykey = myvalue

Summary

You now know exactly where your git config files are. This is very helpful and much more explainable than using the git commands. I'm not sure I was able to simplify it, but it makes at least some sense at the end of the day for us programmers!

Resources

Ry's Git Tutorial here is my BOOK Review