Whenever you do a login, logout, or attempt to log in, everything gets recorded on your system, and there is a specific command that you can use to find out who has logged into your Linux system. In this article, you will see a binary file that is responsible for maintaining records and how to read the binary file using the “utmpdump“ utility.

Source: LXer – What is utmp,wtmp,btmp, and how to read?