How to check the memory of linux

The free command displays the system's used and free memory, including physical memory, interactive area memory (swap) and kernel buffer memory.

Directly enter the free command, it will be displayed as follows (Recommended learning: linux operation and maintenance)

The default display unit of the free command is kb. You can use the free -m and free -g commands to view it, which represent MB and GB respectively.

In addition, free -h will automatically select the unit. Suitable for understanding the capacity unit display

Mem:表示物理内存统计，如果机器剩余内存非常小，一般小于总内存的20%，则判断为系统物理内存不够
Swap: 表示硬盘上交换分区的使用情况，如剩余空间较小，需要留意当前系统内存使用情况及负载，当Swap的used值大于0时，则表示操作系统物理内存不够，已经开始使用硬盘内存了。
第1行数据11G表示物理内存总量；6.5G表示总计分配给缓存(包含buffers与cache)使用的数量，但其中可能部分缓存并未实际使用；
1.3G表示未被分配的内存；shared表示共享内存；4.0G表示系统分配但未被使用的buffers数量；4.7G表示系统分配但未被使用的available数量

ps -eo pmem,pcpu,rss,vsize,args | sort -k 1 -r | less execute the above command to Check the memory usage of each program process , as shown in the figure below. The first column is the percentage of memory occupied by the process. You can see which applications occupy more memory, which can be used to troubleshoot problems:

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