Linux - user commond

# Add user

$/usr/sbin/useradd -d /home/njoonk -m njoonk -g njoonk

# Set password

$/usr/bin/passwd njoonk

# Delete user

$userdel testuser #Only a user.
$userdel -r testuser #Only a user with user's directory.

# Create a public in linux

$ ssh-keygen -t rsa

# Input the public-key into the authorized_keys

$ vi authorized_keys
$ chmod 644 .ssh/authorized_keys