How to use multiple SSH keys for different git accounts

Create different public key

create a different ssh key for each account (GitHub, GitLab, ...)

$ ssh-keygen -t rsa -C "your_email@youremail.com" -f ~/.ssh/github-github_user_name
$ ssh-keygen -t rsa -C "your_email@youremail.com" -f ~/.ssh/gitlab-gitlab_user_name

for example, 2 key pais created as follows:

Key pair 1:

~/.ssh/github-github_user_name
~/.ssh/github-github_user_name.pub

Key pair 2:

~/.ssh/gitlab-gitlab_user_name
~/.ssh/gitlab-gitlab_user_name.pub

Add the private keys

all cached keys can be deleted before

$ ssh-add -D

If you get the following error: "Could not open a connection to your authentication agent."

Try this:

$ eval "$(ssh-agent)"

add these two keys as following

$ ssh-add ~/.ssh/github-github_user_name
$ ssh-add ~/.ssh/gitlab-gitlab_user_name

Modify the ssh config file

create the config file if it does not exist and open it using a text editor (vi / vim / gedit / nano...)

$ cd ~/.ssh/
$ touch config
$ vim config

add all the accounts

#github-github_user_name account
Host gh-github_user_name
    HostName github.com
    User github_user_name
    IdentityFile ~/.ssh/github-github_user_name

#gitlab-gitlab_user_name account
Host gh-gitlab_user_name
    HostName gitlab.com
    User gitlab_user_name
    IdentityFile ~/.ssh/gitlab-gitlab_user_name

Check the saved keys

finally, check the saved keys

$ ssh-add -l

if the ssh keys don't show up, run:

$ ssh-add ~/.ssh/github-github_user_name
$ ssh-add ~/.ssh/gitlab-gitlab_user_name

one of the following methods (A or B) is used

A) Make the config global

the git username and email can be set globally and then use the normal flow to push the code

while working with GitHub

$ git config --global user.name "github_user_name"
$ git config --global user.email "your_email@youremail.com"

while working with GitLab

$ git config --global user.name "gitlab_user_name"
$ git config --global user.email "your_email@youremail.com"

B) Clone the repository and modify the git configuration

clone the repository

$ git clone git@github.com:github_user_name/repo.git repo-github_user_name

if repo-github_user_name is not defined at then end of the command, the folder name will be same as the repo name.

enter the repository folder and modify the git configuration locally

$ cd repo-github_user_name
$ git config user.name "gibhub_user_name"
$ git config user.email "your_email@gmail.com"

$ cd repo-gitlab_user_name
$ git config user.name "giblab_user_name"
$ git config user.email "your_email@gmail.com" 

then use normal flow to push the code

$ git add .
$ git commit -m "your comments"
$ git push

Check your SSH connection (extra)

If you want to connect to your machine via SSH, you can be sure that your ISP or router does not block this protocol and its port by using the following:

$ ssh -T git@github.com

For more use Testing your SSH connection by GitHub

Credits

This is a customized version of Multiple SSH Keys settings for different GitHub account documented by jexchan

Misc

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