View User Logon status in Linux

I,
W command
This command is used to display the users logged on to the system. W command is powerful. It not only shows who logged on to the system, but also shows the current work of these users, the statistical data is more detailed and scientific than the WHO command.

The display items of the W command are arranged in the following order: current time, system start time, number of logged-on users, average load of the system in the last 1 s, 5 S, and 15 s. The data of each user is displayed in the following order: Logon account, terminal name, remote host name, Logon Time, idle time, jcpu, pcpu, and command line of the currently running process.

The jcpu time refers to the time occupied by all processes connected to the terminal (TTY. This time does not include the previous background job time, but includes the time occupied by the currently running background job. The pcpu time refers to the time occupied by the current process (that is, the process displayed in what. The following describes the specific usage and parameters of the command.

II,
Who command
This command is used to view the current online users. This command is very useful. If you want to establish instant communication with other users, such as using the talk command, you must first make sure that the user is online. Otherwise, the talk process cannot be established. Another example is that the system administrator also needs to use the who command to monitor what every login user is doing at this moment.
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Login Name: logon username;

Terminal line: Use a terminal device;

Login Time: the logon time to the system.

The following describes the common parameters of the WHO command.

-M
The same effect as Who am I shows the user name, logon terminal, and logon time in the system.

-Q
Only the user's Logon account and number of logged-on users are displayed.

-S
Ignore, which is equivalent to WHO

-R
You can view the running level of the current system
Run-Level 3 Apr 21 last = s

-H, -- heading displays the title of a row of columns. Common titles are shown in Table 4-2.

3,
Whoami only displays the user name in the system

IV,
Who am I displays the user name, logon terminal, and logon time in the system.
You can view the username you have logged on to the system, which is the same as LOGNAME.

V,
LOGNAME displays the username you have logged on to the system.

Sat,
Last can be used to view the last time you log on to the system. Of course, root can be used to view the logon status of other users.
The last-N user can view the previous n logins of the user.

Seven,
Tty
You can use tty to report connected devices or terminals.