Git

Favourite command

git add . && git commit --amend --no-edit && git push --force-with-lease

Multiple accounts on Github

Make sure both accounts can login using SSH public keys.

One can use the default ~/.ssh/id_ed25519 but the other accounts needs to have specific key files like ~/.ssh/id_ed25519_account2

Then to make it seamless when these accounts are used do the following.

First setup a special host in ~/.ssh/config to handle the second account:

Host github-account2.com
  Hostname github.com
  IdentityFile ~/.ssh/id_ed25519_account2

Already now running git clone git@github-account2.com:someowner/somerepo.git would use the SSH key for account2.

But we can do better.

Git has functionality to replace URL’s, so if we know which paths are for account2 it could be achieved like this:

git config --global url."git@github-account2.com:someowner/".insteadOf "git@github.com:someowner/"

Now it is possible to clone with git clone git@github.com:someowner/somerepo.git, and since it matches ... someowner/ it will use the SSH key for account2.

And git@github.com:otherowner/otherrepo.git would use the default SSH key.

Mapping https to SSH

The same mechanism can be used to remap https://github.com/... URL’s into SSH ones:

git config --global url."git@github.com:otherowner/".insteadOf "https://github.com/otherowner/"
git config --global url."git@github-account2.com:someowner/".insteadOf "https://github.com/someowner/"

(each url."<url>" can have multiple .insteadOf. But setting it will fail, if multiple .insteadOf exists. There is an --add and a --replace-all options to control that.)

This will make requests for https://github.com/... remap and use SSH instead. And by that do SSH public key login.

That combined with:

export GOPRIVATE='github.com/otherowner/*,github.com/someowner/*'

Makes private Golang modules work seamlessly.

Sign commits on Github

Main article.

Step 1 - Produce a GPG key

Either an existing one, check with:

gpg --list-secret-keys --keyid-format=long

Or create a new one:

Run gpg --full-generate-key
Choose your key type, default RSA and RSA is fine, so press Enter.
Choose the key size, must be at least 4096 bits.
Choose the length of time the key should be valid. Default doesn’t expire, so press Enter.
Choose y if everything is correct.

Enter `user ID` information:

Name, use same as Github.
Email, use one that you use to commit.
Comment, can be empty.
Choose o for okay.

Now Linux will prompty you to enter a password for the new key.

Step 1a - Add extra emails

Usually there is more than one email used to commit, so to enter a second email.

Get your GPG key ID:

gpg --list-secret-keys --keyid-format=long

Returns something like:

/Users/hubot/.gnupg/secring.gpg
------------------------------------
sec   4096R/3AA5C34371567BD2 2016-03-10 [expires: 2017-03-10]
uid                          Hubot
ssb   4096R/42B317FD4BA89E7A 2016-03-10

The key ID is the line with sec so 3AA5C34371567BD2.

With the key ID do:

Run gpg --edit-key <GPG key ID>
At the gpg prompt type adduid to add a new user ID.
Enter user ID information as above.
At the gpg prompt type save to store the new user ID.

Step 2 - Export key to Github importable format

To add the GPG key in Github it needs to be in ASCII armor format.

To do that run:

gpg --armor --export <GPG key ID>

The key will look like this:

-----BEGIN PGP PUBLIC KEY BLOCK-----

  ... key content ...

-----END PGP PUBLIC KEY BLOCK-----

Copy everything, and enter in Github -> Settings -> SSH and GPG keys -> New GPG key

Note! If user ID’s are added or remove, the key needs to be exported and imported on Github again.

Step 3 - Set your GPG signing key in Git

Run:

git config --global user.signingkey <GPG key ID>

Step 4 - Sign your commits

Either on a commit by commit basis:

git commit -S -m *your commit message*

Or configure a single repository to allways sign:

git config commit.gpgsign true

Or configure git globally to sign:

git config --global commit.gpgsign true

Git