Multiple github accounts in one computer

Today I've created my second github account after a long time using the service as single user. This account is mostly for professional works in addition to my personal account for open source projects.

I had never had two accounts and was a little lost at first. Here is how I managed my problem (I hope help others):

1. Generate SSH Key for new github user

cd ~/.ssh
ssh-keygen -t rsa -C "user@email.com"

When asked which file write the following:

~/.ssh/id_rsa_githubusername

This will generate two files idrsagithubusername and idrsagithubusername.pub.

You can manually add that to your ssh keys

ssh-add -K id__rsa__githubusername

2. Add new SSH Key to your user on github.com

copy the content of idrsagithubusername.pub:

$ pbcopy < ~/.ssh/id__rsa__githubusername.pub

1. go to https://github.com/settings/ssh
2. click in ADD SSH KEY button on the right
3. paste the content of idrsagithubusername.pub and save it

3. Create SSH config file

$ touch ~/.ssh/config

4. Edit SSH config file with your accounts information

#Default GitHub
Host github-username  //name to identify github account
HostName github.com  //don't change this
User githubusername  //username on github
IdentityFile ~/.ssh/id_rsa_githubusername   //ssh key created

5. Cloning repository for the new user

git clone git@github-username:user/repo.git

NOTE: we change github.com with github-username as specified on our SSH config file.