Viewing Linux memory usage can be achieved through multiple commands. ① Use the free command to quickly view the overall memory status, and execute free -h is more readable; ② Use top or htop to monitor memory changes in real time, and the htop interface is more friendly; ③ Check /proc/meminfo to obtain detailed memory information, suitable for troubleshooting or writing scripts; ④ Use grep to accurately find specific fields, such as MemFree or Swap; ⑤ Press F6 to sort the process by memory in htop, which is convenient for debugging and analysis. Mastering these methods can meet daily needs and avoid omissions in detail.
It is not difficult to check memory usage under Linux system, but many users may not know what methods are available when they first come into contact. Commonly used commands and tools are actually very direct and can provide detailed information.

Use the free
command to quickly view
This is the easiest and most common way to quickly understand the overall memory status.

After executing this command, you will see an output similar to the following:
free -h
The output results include total memory, used memory, free memory, and cache usage. The -h
parameter is added to make the number easier to read (such as displaying it in GB or MB).

If you just want to see how much memory there is left in the system, this command is enough.
Use top
or htop
to view real-time status
top
is a tool that monitors system resources in real time, and it will also display memory usage.
Run the command:
top
The memory usage overview can be seen in the top area. Compared to free
, it is more suitable for observing memory changes trends, especially when the system load is high.
If you want the interface to be better and the operation is more convenient, you can install htop
:
sudo apt install htop # Debian/Ubuntu system htop
Its color distinction is more obvious, and it is easier to scroll to view the process.
View details via /proc/meminfo
This is a hidden but very useful way. Linux places a lot of system information under /proc
, and the meminfo
file records detailed memory data.
You can use the following command to view:
cat /proc/meminfo
You can see various details here, such as the specific usage of Slab, Cached, Buffers, etc. This file will be helpful if you are troubleshooting memory problems or if you need to get exact values ??by writing scripts.
Tips: Use grep
to accurately find specific fields
For example, if you want to only read the "available memory" information, you can do this:
grep MemFree /proc/meminfo
Or check multiple related items at once:
-
grep -E 'Mem|Swap' /proc/meminfo
-
free -m | grep Mem
- Press F6 in
htop
to choose to sort the process by memory
These small operations are quite practical when debugging or writing scripts.
Basically these commonly used methods. Different tools can be used for different scenarios, and it is not complicated, but it is easy to ignore details, such as unit conversion and whether cache is included. By mastering these commands, you can basically cope with daily needs.
The above is the detailed content of How to check memory usage in Linux. For more information, please follow other related articles on the PHP Chinese website!

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