As a Linux user, you must be aware of the importance of monitoring system resources such as memory usage. Memory is a crucial component of your system, and if it is not managed properly, it can lead to system crashes, poor performance, and other issues. In this article, we will discuss how to check memory usage in Linux.
What is Memory Usage?
Memory usage refers to the amount of memory that is currently being used by the system. In Linux, memory is divided into two categories: physical memory and virtual memory. Physical memory is the actual RAM installed on your system, while virtual memory is a combination of RAM and swap space (hard disk space used as an extension of RAM).
When your system runs out of physical memory, it starts using virtual memory. However, using too much virtual memory can slow down your system because hard disk access is slower than RAM access.
Checking Memory Usage in Linux
There are several tools available in Linux to check memory usage. In this section, we will discuss some commonly used tools.
1. free
The free command is used to display the amount of free and used memory in the system. To use this command, open the terminal and type the following command:
free -hThe -h option is used to display the memory usage in a human-readable format. The output will look like this:
total used free shared buff/cache available
Mem: 7.8G 1.6G 4.4G 120M 1.8G 5.9G
Swap: 2.0G 0B 2.0GThe Mem column shows the total amount of physical memory, the amount of memory used, and the amount of free memory. The Swap column shows the total amount of swap space, the amount of swap space used, and the amount of free swap space.
2. top
The top command is used to display real-time information about the system, including memory usage. To use this command, open the terminal and type the following command:
topThe output will look like this:
top - 11:17:18 up 1:30, 1 user, load average: 0.00, 0.02, 0.00
Tasks: 181 total, 1 running, 180 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 0.3 sy, 0.0 ni, 99.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 8167592 total, 4411408 free, 1932480 used, 1821704 buff/cache
KiB Swap: 2097148 total, 2097148 free, 0 used. 5472000 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2771 root 20 0 551520 42984 34584 S 0.0 0.5 0:00.76 Xorg
3077 user 20 0 888456 77228 47552 S 0.0 0.9 0:08.89 gnome-shell
3193 user 20 0 495032 32928 26756 S 0.0 0.4 0:01.70 gnome-terminal-
3199 user 20 0 31608 3728 3208 R 0.0 0.0 0:00.03 top
1 root 20 0 225288 14508 9328 S 0.0 0.2 0:01.54 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 0 0 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/0
5 root 0 0 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H The KiB Mem line shows the total amount of physical memory, the amount of memory used, and the amount of free memory. The KiB Swap line shows the total amount of swap space, the amount of swap space used, and the amount of free swap space. The %MEM column shows the percentage of memory used by each process.
3. htop
The htop command is a more advanced version of the top command. It provides real-time information about the system, including memory usage, in a more user-friendly interface. To use this command, open the terminal and type the following command:
htopThe output will look like this:
The MEM% column shows the percentage of memory used by each process.
Conclusion
Checking memory usage is an essential task for any Linux user. In this article, we discussed some commonly used tools to check memory usage, including free, top, and htop. By using these tools, you can monitor your system’s memory usage and ensure that it is managed properly.