How to Monitor Linux Users and Processes in Real-Time?

Linux is an open-source operating system that has become increasingly popular among developers and system administrators. It is known for its stability, security, and flexibility, and is widely used in enterprise environments. However, as with any operating system, it is important to keep an eye on system performance to ensure that everything is running smoothly. This is where monitoring users and processes in real time becomes essential.

In this article, we'll be discussing how to monitor Linux users and processes in real time.

We'll cover some of the most popular tools used for this purpose, such as w, who, last, top, htop being used to manage users and processes in a Linux sub-system. In the next section of the article, we'll explain how to use these tools to monitor system performance in real time. So, let's get started!

Monitoring Linux Users in Real-Time

First, we are going to talk about how to monitor Linux users in real-time. Some of the most commonly used command-line tools that will help you keep an eye on user activity are w, who, and last commands. Let’s understand each of them one by one in detail.

1. The W Command

The 'w' command is responsible for showing you a list of all the currently logged-in users along with their login time, current processes, and system load.

The command is very straightforward to use. Simply type 'w' in your terminal to see the list of users currently logged into your system −

Example

$ w

Output

 16:36:11 up 7 days,  6:21,  1 user,  load average: 0.07, 0.02, 0.00
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
user1    pts/0    192.168.1.1      09:13    0.00s  0.02s  0.00s w

The output of the above command shows that there is one user currently logged in, user1. It also shows the time of their login, their terminal (TTY), their remote IP address, and the current system load.

2. The Who Command

The 'who' command is very similar to 'w' command. The only difference is that it only shows you a list of currently logged-in users without much additional details.

Again, using this command is also very easy. Simply type ‘who’ in your Linux terminal.

Example

$ who

Output

user1  pts/0        2022-04-01 09:13 (192.168.1.1)

As you can see in the above output, the 'who' command only shows you a list of logged-in users, their terminal, and their IP address, unlike the ‘w’ command which showed much more information.

3. The Last Command

The 'last' command shows you a list of all the recent logins and logouts. To see the list, type 'last' in your terminal −

Example

$ last

Output

user1    pts/0        192.168.1.1      Fri Apr  1 09:13   still logged in
user2    pts/1        192.168.1.2      Thu Mar 31 14:05 - 14:14  (00:08)
user3    pts/2        192.168.1.3      Thu Mar 31 13:44 - 13:49  (00:05)

As you can observer in the output above, the 'last' command shows you a list of users who logged in and logged out recently. It also shows the date, time, and IP address of each user.

Now that we know about some basic command-line tools to monitor users in real-time. Let’s move ahead and understand how can we manage processes in real-time

Monitoring Linux Processes in Real-Time

In this section of the article, we are going to cover how to monitor Linux processes in real-time for a Linux system. There are again several tools available for this purpose, but we will focus on two popular command-line tools: top and htop.

1. Top Command

First, let's look at the top command. The top is a built-in command-line tool that displays real-time system information, including CPU usage, memory usage, and running processes.

To launch the top, open a terminal and type "top" into the command prompt. The output will update in real time and display the current state of your system.

Example

$ top

Here is an example output of the top command −

Output

top - 22:07:36 up  2:24,  2 users,  load average: 0.00, 0.00, 0.00
Tasks: 127 total,   1 running, 126 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.3 us,  0.3 sy,  0.0 ni, 99.4 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
MiB Mem :   7941.1 total,   4157.1 free,   2448.8 used,   1335.3 buff/cache
MiB Swap:   2048.0 total,   2048.0 free,      0.0 used.   5045.6 avail Mem 

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND  
 1432 root      20   0  339968  55808  19112 S   1.0   0.7   0:44.08 Xorg     
 2462 username  20   0  908564  95916  54456 S   0.3   1.2   0:10.32 gnome-te+
 2586 username  20   0 2203836 297076 111832 S   0.3   3.6   1:01.09 gnome-sh+
 3122 username  20   0 2415716 407556  92312 S   0.3   5.0   1:47.80 firefox 
    1 root      20   0  168952   9724   6664 S   0.0   0.1   0:02.62 systemd  
    2 root      20   0       0      0      0 S   0.0   0.0   0:00.03 kthreadd 

As you can see, the output shows the process ID (PID), user, CPU usage, memory usage, and more. You can also sort the output based on different criteria, such as CPU usage or memory usage. To do this, press the "O" key (capital letter O) and then choose the field you want to sort by.

Next, let's look at the htop command.

2. Htop Command

Htop is a more advanced version of top that provides a more user-friendly interface and additional features, such as the ability to scroll vertically and horizontally through the process list.

The output of htop returns color-coded output that makes it easier to read and understand. It also offers additional features such as the ability to search for a specific process by name, filter processes by CPU usage, and even kill processes directly from the htop interface.

To launch htop, open a terminal and type "htop" into the command prompt. The output will update in real time and display the current state of your system.

$ htop

Here's an example of what the output looks like

As you can see in the output image above, htop provides a lot of useful information about the processes running on your system, including their CPU and memory usage, process IDs, and more. You can navigate the interface using your arrow keys, and you can sort processes by various criteria by pressing the corresponding key (e.g. F6 to sort by CPU usage).

In addition to the top and htop commands, there are several other tools available for monitoring Linux processes in real time, such as iotop, nethogs, and iftop.

Conclusion

In this article, we have discussed how to monitor Linux users and processes in real time. First, we covered some of the commonly used command-line tools, such as w, who, and last, to monitor Linux users. In the latter half of the article, we discussed some of the most popular tools used for monitoring Linux users and processes, such as top, htop. By using these tools, you can identify performance bottlenecks, troubleshoot issues, and optimize your system to run smoothly. Whether you are a system administrator or a developer, these tools will help you monitor and optimize your Linux system for maximum efficiency.