who_just_login.py

# coding: utf-8
import commands
import time


def get_current_ssh_user():
    output = commands.getoutput('users')
    return output.split(' ') if output else None

def get_current_ssh_user_set():
    users = get_current_ssh_user()
    return set(users) if users else set()


if __name__ == '__main__':
    init_user_set = get_current_ssh_user_set()
    print 'init_users are %s' % commands.getoutput('users')

    # loop
    current_user_set = init_user_set
    while True:
        new_user = get_current_ssh_user_set() - current_user_set.intersection(get_current_ssh_user_set())
        if new_user:
            print 'new user %s login at %s' % (new_user, time.strftime('%Y-%m-%d %H:%M:%S'))
            current_user_set = get_current_ssh_user_set()
        new_logout = current_user_set - current_user_set.intersection(get_current_ssh_user_set())
        if new_logout:
            print 'new user %s logout at %s' % (new_logout, time.strftime('%Y-%m-%d %H:%M:%S'))
            current_user_set = get_current_ssh_user_set()
            
        time.sleep(5)