## Generate new SSH key
`$ ssh-keygen -t rsa -C "your_email@email.com"`

for example, created key for 2 accounts
```
~/.ssh/id_rsa_user1
~/.ssh/id_rsa_user2
```

## Add SSH keys to ssh-agent
```
$ ssh-add -K ~/.ssh/id_rsa_user1
$ ssh-add -K ~/.ssh/id_rsa_user2
```

you also need to modify `.ssh/config`
```
#user1 account
Host github.com-user1
	HostName github.com
	User git
	IdentityFile ~/.ssh/id_rsa_user1

#user2 account
Host github.com-user2
	HostName github.com
	User git
	IdentityFile ~/.ssh/id_rsa_user2
```

## Add SSH key to github account
copy key to your clipboard then paste it into your github setting
`$ pbcopy < ~/.ssh/id_rsa_{user}.pub`

## Usage
**setting global git user**
```
git config --global user.email "global_email@email.com"
git config --global user.name "global-name"
```

**setting local git user**
```
git config user.email "local_email@email.com"
git config user.name "local-name"
```

then, you also have to delete all SSH keys and add a needed key because global key always overide the local one
```
# delete all keys before
$ ssh-add -D

# add needed key
$ ssh-add ~/.ssh/id_rsa_{user}
```

use `ssh-add -l` to list all added keys

## Bonus
**shell command**
```
guser() {
  G_USER=${1:="global-name"}
  if [ $G_USER = "local-name" ]
  then
    git config user.name "local-name"
    git config user.email "local_email@email.com"
  fi
  ssh-add -D
  ssh-add $HOME/.ssh/id_rsa_$G_USER
  ssh-add -l
}
```

you can use `guser` for global user and `guser {local-name}` for local user