Configuring and managing multiple SSH keys for GIT accounts, in Ubuntu is shown below:
Using ssh-keygen
create a public/private key and name it as user1_github
, user1_bitbucket
create a file ~/.ssh/config
and put the following in it.
# user1 github account
Host user1_github
HostName github.com
PreferredAuthentications publickey
IdentityFile ~/.ssh/user1_github
# user1 bitbucket account
Host user1_bitbucket
HostName bitbucket.org
PreferredAuthentications publickey
IdentityFile ~/.ssh/user1_bitbucket
Once the configuration is done, you can checkout as below
$ git clone git@user1_github:user1/my_github_repo.git
$ git clone git@user1_bitbucket:user1/my_bitbucket_repo.git
Hope this helps!