How to Monitor RAM Usage on Linux

Memory is an essential component of your Linux system. All programs and files will be copied into RAM at some point, which makes it a precious resource to have. In this tutorial, we will show you how to monitor the RAM usage in your system with a few important commands in Linux.

top Command

The top command is a useful tool that displays information about memory usage and each service utilizing it. To monitor the RAM usage simply execute:

$ top

Output using top to display memory usage

To sort the output by memory usage you can press the m key. To exit from top, just press q.

htop Command

htop is a interactive tool with an easy-to-read breakdown of current memory usage, along with other relevant system information.

htop doesn’t come installed by default on Linux. To install it:

$ sudo apt install htop # Debian/Ubuntu
$ sudo dnf install htop # Fedora/Alma/Rocky/CentOS
$ sudo pacman -S htop # Arch Linux / Manjaro

To view the memory usage using this command, execute:

$ htop

You can use your mouse to click on the memory column (MEM%) to sort processes by their memory usage. To exit from htop, just press q.

free Command

As its name implies, the free command is used to display the total amount of free memory. At the same time it also shows the total amount of used system memory. To use this command, execute:

$ free

Output using free to display memory usage

If you want the output to be more easy to read, you can add the -h (human-readable) option to the command.

$ free -h

Output displaying memory usage

Or if you prefer the output to be displayed in megabytes only, simply add the -m flag to the command:

$ free -m

Output displaying memory usage in mb

vmstat Command

Another useful command tool that helps you display information about the virtual memory statistics and memoy usage. To use this command execute:

$ vmstat

Using vmstat to display memory information

If you want to display a summary of the memory usage instead, add the -s parameter to the command:

$ vmstat -s

Displaying a summary of memory usage with vmstat

The /proc/meminfo file

In this file we can find all the important information about the total amount of the free and used system memory. To view the content of this file you can use the cat command:

$ cat /proc/meminfo

Monitoring RAM Usage Linux via GUI

There are a lot of GUI applications available on Linux that can monitor RAM usage, in case you would prefer them over looking at the terminal. A good one for everyday use is GNOME System Monitor. Here’s how to install it:

$ sudo apt install gnome-system-monitor # Debian/Ubuntu
$ sudo dnf install gnome-system-monitor # Fedora/Alma/Rocky/CentOS
$ sudo pacman -S gnome-system-monitor # Arch Linux / Manjaro

Then open the application or launch from terminal:

$ gnome-system-monitor

You can see current RAM usage under the ‘Resources’ tab.

Monitoring RAM usage in GNOME System Monitor app

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