Linux free command

Linux Command Reference

The Linux free command is used to display memory status.

The free command displays memory usage, including physical memory, virtual swap file memory, shared memory segments, and buffers used by the system kernel, etc.

Syntax

free [-bkmotV][-s <间隔秒数>]

Parameter description：

• -b Displays memory usage in bytes.
• -k Displays memory usage in KB.
• -m Displays memory usage in MB.

• -h Displays memory usage in an appropriate unit; the maximum is three digits, and the corresponding unit value is automatically calculated. Units are:

  B = bytes
  K = kilos
  M = megas
  G = gigas
  T = teras

• -o Does not display the buffer adjustment column.
• -s<interval seconds> Continuously observe memory usage status.
• -t Displays the total memory column.
• -V Displays version information.

Examples

Display memory usage

# free //显示内存使用信息
total used free shared buffers cached
Mem: 254772 184568 70204 0 5692 89892
-/+ buffers/cache: 88984 165788
Swap: 524280 65116 459164

Display memory usage information in total form.

# free -t //以总和的形式查询内存的使用信息
total used free shared buffers cached
Mem: 254772 184868 69904 0 5936 89908
-/+ buffers/cache: 89024 165748
Swap: 524280 65116 459164
Total: 779052 249984 529068

Periodically query memory usage information.

# free -s 10 //每10s 执行一次命令
total used free shared buffers cached
Mem: 254772 187628 67144 0 6140 89964
-/+ buffers/cache: 91524 163248
Swap: 524280 65116 459164

total used free shared buffers cached
Mem: 254772 187748 67024 0 6164 89940
-/+ buffers/cache: 91644 163128
Swap: 524280 65116 459164

Linux Command Reference