Configuration deep dive

Why this matters

Two problems this solves. The first is "why is this setting what it is?", which --show-origin answers in one line. The second is committing to a work repository with a personal address, which includeIf prevents permanently.

Where a setting comes from

$ git config --list --show-origin | grep user

file:~/.gitconfig	user.name=You
file:~/.gitconfig	user.email=you@example.com

Or for one setting:

$ git config --show-origin --get user.email

file:~/dev/work.gitconfig	ana@northwind-trails.example

Levels, from weakest to strongest (lesson 3.4):

The later ones win. The worktree level exists for lesson 18.6 and is rarely needed otherwise.

includeIf: identity by folder

The reliable fix for two identities on one machine. In ~/.gitconfig:

[user]
	name = Your Name
	email = you@personal.example

[includeIf "gitdir:~/dev/work/"]
	path = ~/dev/work/.gitconfig-work

[user]
	name = Ana Lopez
	email = ana@northwind-trails.example

Then, inside a repository under ~/dev/work/:

$ git config --get user.email

ana@northwind-trails.example

And anywhere else:

$ git config --get user.email

you@example.com

Three details that trip people up:

• The trailing slash matters. gitdir:~/dev/work/ matches everything inside; without it the match is exact.
• The path is relative to the file doing the including, so absolute paths or ~ are safest.
• It matches the repository's location, not the remote. Sorting your folders by employer is what makes it work.

includeIf can carry more than identity: signing keys, a different SSH command, different aliases (lesson 18.3).

Aliases

$ git config --global alias.lg "log --oneline --graph -10"
$ git lg

* d3b92ec chore: add CI configuration and contributing guide
* b81702c docs: add getting started guide and FAQ
* 28593d2 feat: add the trail list command
* e653def chore: start the trailguide project

A few worth having, chosen because they are the ones people type dozens of times a day:

[alias]
	st = status -sb
	lg = log --oneline --graph --decorate -20
	last = log -1 --stat
	unstage = restore --staged
	pushf = push --force-with-lease
	wip = commit -am "wip"
	please = push --force-with-lease

pushf earns its place by keeping the dangerous spelling out of your fingers (lesson 12.8).

An alias starting with ! runs a shell command instead of a Git subcommand, which is powerful and worth using sparingly, since it stops being portable.

Settings worth knowing

Per-repository overrides

Inside a repository, git config user.email … writes to .git/config and beats the global. That is the manual version of includeIf, useful for the one repository that does not fit your folder layout:

$ git config user.email "ana@northwind-trails.example"
$ git config --show-origin --get user.email

How to do it

$ git config --list --show-origin
$ git config --show-origin --get <key>
$ git config --global --edit
$ git config --global alias.st "status -sb"

Common mistakes

• Setting the identity per repository by hand and forgetting on the next clone. includeIf is the fix.
• Omitting the trailing slash in a gitdir: condition.
• A relative include path, which resolves against the including file and surprises people.
• Aliases that hide danger, such as one for push --force.
• help.autocorrect left on, which runs a command you did not type.
• Editing .git/config while a Git command is running.