Managing Multiple GitHub Accounts

Have you ever tried to push code to your personal GitHub repository, only to encounter a frustrating error like this?

```

ERROR: Permission to personal-user/repo.git denied to office-user.

```

It is a classic headache. Your computer is "helpfully" trying to use your professional work credentials for your personal projects. Here is the cleanest way to fix it using the SSH config method.

The Problem

By default, Git and SSH often grab the first key they find (usually your work key) and offer it to GitHub. GitHub recognizes you as your work account, realizes that account does not have permission to write to your personal repo, and rejects the push.

The Solution: The ~/.ssh/config File

The most elegant fix is to create aliases for GitHub. This tells your computer exactly which key to use for which account.

Step 1: Create Your SSH Keys

Ensure you have separate keys for both accounts:

- ~/.ssh/id_rsa_office (or id_ed25519_office)

- ~/.ssh/id_rsa_personal (or id_ed25519_personal)

Generate a new key if needed:

```bash

ssh-keygen -t ed25519 -C "you@work.com" -f ~/.ssh/id_ed25519_office

ssh-keygen -t ed25519 -C "you@gmail.com" -f ~/.ssh/id_ed25519_personal

```

Add each public key to the correct GitHub account under Settings → SSH and GPG keys.

Step 2: Edit Your SSH Config

Open your terminal and type:

```bash

nano ~/.ssh/config

```

Step 3: Add the Configuration Block

Paste the following (adjust filenames to match yours):

```

# Office GitHub Account

Host github.com-office

HostName github.com

User git

IdentityFile ~/.ssh/id_ed25519_office

IdentitiesOnly yes

# Personal GitHub Account

Host github.com-personal

HostName github.com

User git

IdentityFile ~/.ssh/id_ed25519_personal

IdentitiesOnly yes

```

IdentitiesOnly yes prevents SSH from offering other keys and accidentally picking the wrong one.

Step 4: Update Your Remote URL

When you clone a personal repo, use the alias instead of github.com:

```bash

git clone git@github.com-personal:your-username/your-repo.git

```

If you already have a project folder, update the remote:

```bash

git remote set-url origin git@github.com-personal:your-username/your-repo.git

```

For work repos, use github.com-office in the same way.

Step 5: Set Local Git Identity

Make sure commits use the correct name and email inside each project:

```bash

git config user.name "Your Name"

git config user.email "you@gmail.com"

```

Use git config --local so each repo keeps its own identity.

Step 6: Test the Connection

```bash

ssh -T git@github.com-personal

ssh -T git@github.com-office

```

You should see a success message naming the correct GitHub user for each host.

Why This Works

By using github.com-personal in your remote URL, you trigger the matching block in your SSH config. Your machine knows: for this URL, use the personal key and ignore the office one.

Conclusion

No more switching keys manually or hitting permission errors. With a small edit to ~/.ssh/config, you can move seamlessly between professional work and personal open-source projects.