Live with multiple Git accounts

1. Generate a new SSH key-pair for each of Git account.

  $ ssh-keygen -t rsa -b 4096 -C "[email protected]" -f ~/.ssh/id_rsa_benjaminv_github
  $ ssh-keygen -t rsa -b 4096 -C "[email protected]" -f ~/.ssh/id_rsa_bendhu_github
  $ ssh-keygen -t rsa -b 4096 -C "[email protected]" -f ~/.ssh/id_rsa_benhu1_gitlab

  # The -C option is a comment to help identify the key.
  # The -f option specifies the file name for the key pair.

2. Add the SSH keys to your SSH-agent

  $ ssh-add ~/.ssh/id_rsa_benjaminv_github
  $ ssh-add ~/.ssh/id_rsa_bendhu_github
  $ ssh-add ~/.ssh/id_rsa_benhu1_gitlab

And make these persistent for new terminal sessions by enable AddKeysToAgent yes in STEP 4.

3. Add the public keys to your GitHub accounts respectively.

Visit https://github.com/settings/keys and use “New SSH Key”

# copy public key to clipboard without opening it
% pbcopy < ~/.ssh/id_rsa_benjaminv_github.pub
% pbcopy < ~/.ssh/id_rsa_bendhu_github.pub
% pbcopy < ~/.ssh/id_rsa_benhu1_gitlab.pub

paste the public key to your GitHub account and add a name to identify it.

4. Managing Overall SSH-Keys

By default the file needed is located at ~/.ssh/config

add following lines to the end of the file

# Work github account
Host github.com
  HostName github.com
  User git
  AddKeysToAgent yes
  UseKeychain yes
  IdentityFile ~/.ssh/id_ed25519_werd_github

# Work gitlab account
Host gitlab.com
  HostName gitlab.com
  User bgit
  AddKeysToAgent yes
  UseKeychain yes
  IdentityFile ~/.ssh/id_rsa_gitlab

# Personal github account
Host github.com.personal
  HostName github.com
  User git
  AddKeysToAgent yes
  UseKeychain yes
  IdentityFile ~/.ssh/id_rsa_benjaminv_github

5. Which Account to Use by Default?

The global Git configuration file is stored at $HOME/.gitconfig on all platforms.

This defines the default values for all Git commands.

[user]
  email = [email protected]
  name = ben
[init]
  defaultBranch = main    # stop using master as default branch

to edit it,

$ git config --global user.name "ben"
$ git config --global user.email "[email protected]"

6. Cloning GitHub repositories using no-default accounts

instead of using github.com:benjaminv/benjaminv,
use github.com.personal:benjaminv/benjaminv
to match the configuration in ~/.ssh/config

6.1 Update repo already cloned before this configuration

6.1.1 Update the remote git url

% git remote set-url origin "[email protected]:benjaminv/starting-react.git"
# mind the .personal added to github.com

6.1.2 Update the local user

% git config --local user.name "ben"
% git config --local user.email "[email protected]"

verify the changes by

% cat .git/config

# It looks like following

# [core]
#         repositoryformatversion = 0
#         filemode = true
#         bare = false
#         logallrefupdates = true
#         ignorecase = true
#         precomposeunicode = true
# [remote "origin"]
#         url = [email protected]:benjaminv/starting-react.git
#         fetch = +refs/heads/*:refs/remotes/origin/*
# [branch "main"]
#         remote = origin
#         merge = refs/heads/main
# [user]
#         name = ben
#         email = [email protected]

7. Confirming This is Working

% ssh -T [email protected]

# Hi benjaminv! You've successfully authenticated, but GitHub does not provide shell access.

# Mind the username here, it is benjaminv NOT my default Git account name
GitHub Gitlab macOS plist