Linux who command
Use who command is used to find current logged in users in your system along with other useful details. You can find details like remote IP address, terminal details, date/time of login etc.
$ who [options]
Find All Login Users
List all users currently logged in to your system.
root pts/9 2017-09-05 17:32 (192.168.1.13)
Find Current Login User
You can also use the following command to print username of current logged in user.
$ who am i