Linux Server Construction

LINUX-Frequently used commands

free command　Checking the memory status of Linux

Ｓyntax

free [Option]

The free command is a command to check the memory status of Linux.
The items displayed include total memory, used space, free space, buffers, and cache. These memory status is displayed in real time.
The free command displays the data based on the "/proc/meminfo" file, so you can run "cat /proc/meminfo will give you the same result.

Frequently used options

-b Display memory capacity in bytes
-k Display memory capacity in kilobytes
-m Display memory capacity in megabytes
-g Display memory capacity in gigabytes
-t Show total memory and swap space

Example: Checking the memory status of Linux.

$ free

total used free shared buffers cached

Mem: 8061116 7944800 116316 220 7172 105892

-/+ buffers/cache: 7831736 229380

Swap: 2097148 2097148 0

Mem	Main memory size（※1）
/+buffers/cache	Memory size including page cache and buffer cache
Swap	Memory size of the swap area
total	Total capacity（※2）
used	Capacity for use
free	free space
shared	Shared memory (memory in an area that can be shared between processes)
buffers	buffer cache
cached	page cache
※1：The size of the main memory does not include the buffer cache and page cache. ※2：Memory used by the OS for disk cache (page cache, buffer cache, etc.) is also included.

Example: Display the total physical memory and swap space

$ free -mt

total used free shared buffers cached

Mem: 7872 7750 121 0 3 89

-/+ buffers/cache: 7657 214

Swap: 2047 2047 0

Total: 9920 9798 121

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