Create new user

To generate SSH Public key from Private key use:

ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub

1. Add User

useradd User.Name -g users

2. Create home folder, ssh folder and change permissions

mkdir -p /home/User.Name/.ssh
chmod 700 /home/User.Name/.ssh

3. Add ssh public key

echo "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCnlzGwyX5JdWkfRlaE30N7ZNqKcvlPyckP+YDWAN+rpXp2KW9p611l2sNaNBeVPLffO3dQM9y1YMiZIVXWW5xjYm5b0ispzrmuLmTodVmRxIzxG84u0RER9F3g4QRxq4vODR4bKSIMUr1XEAN9BI99kXjU+zuh871bePPxtYrBuSEBerNqk/oAtWYIG+XTYi8f2E4opz+yCYWQJtlZavIJheTf0+Zvy5YKhjHWPNWjQYMeMZchHyhBhUP+/cYJ8TPdvNUl+O0K91ZDWSTxHY8EWNeb45bskf4unKLIfckL8xMIJv1mWu0WPad17rfq6eyAnFDan26YGqKvsyLPKygB username@linux" > /home/User.Name/.ssh/authorized_keys

4. Change permissions of ssh public key

chmod 644 /home/User.Name/.ssh/id_rsa.pub

5. Change permissions of authorized_keys file

chmod 600 /home/User.Name/.ssh/authorized_keys

6. Change permissions of /home

chmod 755 /home/User.Name