SSH login without password

ssh config.md

Create rsa key

user$ ssh-keygen -t rsa

Create .ssh in server target (The directory may already exist, which is fine)

user$ ssh user@server mkdir -p .ssh

Append user's new public key to user@server:.ssh/authorized_keys

user$ cat .ssh/id_rsa.pub | ssh user@server 'cat >> .ssh/authorized_keys'

SSH config

Edit: ~/.ssh/config

Host [regex-host]
 User [user]
 IdentityFile [file.pem]

Send to multiples servers

 for i in {1..5};
 do
  cat ~/.ssh/id_rsa.pub | ssh user@"server$i" 'cat >> ~/.ssh/authorized_keys'
 done