Add til about having multiple git identities

git/multiple-git-identities.md

@@ -0,0 +1,82 @@
+# Setup multiple git identities & git user informations
+https://gist.github.com/bgauduch/06a8c4ec2fec8fef6354afe94358c89e
+
+> /!\ Be very carrefull in your setup : **any misconfiguration make all the git config to fail silently !**
+Go trought this guide step by step and it should be fine :wink:
+
+## Setup multiple git ssh identities for git
+* Generate your SSH keys as per your git provider documentation.
+* Add each public SSH keys to your git providers acounts.
+* In your `~/.ssh/config`, set each ssh key for each repository as in this exemple:
+
+  ``` bash
+	Host github.com
+		HostName github.com
+		User git
+		IdentityFile ~/.ssh/github_private_key
+		IdentitiesOnly=yes
+	Host gitlab.com
+		Hostname gitlab.com
+		User git
+		IdentityFile ~/.ssh/gitlab_private_key
+		IdentitiesOnly=yes
+  ```
+
+## Setup dynamic git user email & name depending on folder
+
+> /!\ Require git 2.13+ for conditional include support.
+
+The idea here is to use a different git user name & email depending on the folder you are in.
+
+* In your `~/.gitconfig`, **remove** the `[user]` block and add the following (adapt this exemple to your needs) :
+
+  ``` bash
+	[includeIf "gitdir:~/code/personal/"]
+		path = .gitconfig-personal
+	[includeIf "gitdir:~/code/professional/"]
+		path = .gitconfig-professional
+  ```
+* In your `~/.gitconfig-personal`, add your personnal user informations:
+
+  ``` bash
+	[user]
+		email = user.personal@users.noreply.github.com     # note we use the noreply github mail
+		name = personal_username
+  ```
+* In your `~/.gitconfig-professional`, add your professional user informations:
+
+  ``` bash
+	[user]
+		email = user.professional@dns.com
+		name = professional_username
+  ```
+
+## Test your setup
+* Now each repository will use the custom user info setup depending on the top-level folder.
+* Check your settings are taken into account, for instance in `~/code/personal/` :
+
+  ``` bash
+  $ cd ~/code/personal/
+  $ git config --get user.email    	# should return user.personal@users.noreply.github.com as per the exemple
+  $ git config --get user.name     	# should return personal_username as per the exemple
+  $ git config --get user.signingkey	# should return the GPG key ID as configured for the user
+  ```
+* Do the same for each folder you have setup.
+* You can also display and check the global git config: `git config --list --global`
+  * Or just the local config for the repository folder you are in: `git config --list`
+* Done !
+
+
+## Update & tip
+
+For your information you must now specify the .git folder in the gitdir such as :
+
+```
+[includeIf "gitdir:~/code/personal/repo1/.git"]
+```
+
+Another useful tip, you can use globbing on parent directory to detect new repos without editing your git-config file :
+
+```
+[includeIf "gitdir:~/code/personal/**/.git"]
+```