FREE(1) User Commands FREE(1)

NAME

free – Display amount of free and used memory in the system

顯示記憶體使用率

SYNOPSIS

free [options]

DESCRIPTION

free displays the total amount of free and used physical and swap mem‐
ory in the system, as well as the buffers and caches used by the ker‐
nel. The information is gathered by parsing /proc/meminfo. The dis‐
played columns are:

此指令讀取位於 /proc/meminfo 內的記憶體資料

total Total installed memory (MemTotal and SwapTotal in /proc/meminfo)

總記憶體大小

used Used memory (calculated as total – free – buffers – cache)

已用的記憶體大小

free Unused memory (MemFree and SwapFree in /proc/meminfo)

未使用的記憶體大小

shared Memory used (mostly) by tmpfs (Shmem in /proc/meminfo)

已用的共享記憶體

buffers
Memory used by kernel buffers (Buffers in /proc/meminfo)

已用的緩存

cache Memory used by the page cache and slabs (Cached and SReclaimable
in /proc/meminfo)

已用的快取

buff/cache
Sum of buffers and cache

已用緩存與快取的總數

available
Estimation of how much memory is available for starting new ap‐
plications, without swapping. Unlike the data provided by the
cache or free fields, this field takes into account page cache
and also that not all reclaimable memory slabs will be reclaimed
due to items being in use (MemAvailable in /proc/meminfo, avail‐
able on kernels 3.14, emulated on kernels 2.6.27+, otherwise the
same as free)

可分配的記憶體大小

OPTIONS

-b, –bytes
Display the amount of memory in bytes.

-k, –kibi
Display the amount of memory in kibibytes. This is the default.

-m, –mebi
Display the amount of memory in mebibytes.

-g, –gibi
Display the amount of memory in gibibytes.

–tebi Display the amount of memory in tebibytes.

–pebi Display the amount of memory in pebibytes.

–kilo Display the amount of memory in kilobytes. Implies –si.

–mega Display the amount of memory in megabytes. Implies –si.

–giga Display the amount of memory in gigabytes. Implies –si.

–tera Display the amount of memory in terabytes. Implies –si.

–peta Display the amount of memory in petabytes. Implies –si.

以上為顯示容量單位

-h, –human
Show all output fields automatically scaled to shortest three
digit unit and display the units of print out. Following units
are used.

B = bytes
Ki = kibibyte
Mi = mebibyte
Gi = gibibyte
Ti = tebibyte
Pi = pebibyte

If unit is missing, and you have exbibyte of RAM or swap, the
number is in tebibytes and columns might not be aligned with
header.

顯示3位數單位

-w, –wide
Switch to the wide mode. The wide mode produces lines longer
than 80 characters. In this mode buffers and cache are reported
in two separate columns.

寬模式，緩存與快取分開顯示

-c, –count count
Display the result count times. Requires the -s option.

設定刷新次數，滿足刷新次數後中止指令。須與 -s 選項一起使用

-l, –lohi
Show detailed low and high memory statistics.

顯示最高與最低記憶體使用率

-s, –seconds delay
Continuously display the result delay seconds apart. You may
actually specify any floating point number for delay using ei‐
ther . or , for decimal point. usleep(3) is used for microsec‐
ond resolution delay times.

設定顯示刷新秒數

–si Use kilo, mega, giga etc (power of 1000) instead of kibi, mebi,
gibi (power of 1024).

使用10進制代替2進制

-t, –total
Display a line showing the column totals.

顯示記憶體+置換總量

–help Print help.

顯示幫助

-V, –version
Display version information.

顯示版本資料

FILES

/proc/meminfo
memory information

BUGS

The value for the shared column is not available from kernels before
2.6.32 and is displayed as zero.

Please send bug reports to
⟨[email protected]⟩

SEE ALSO
ps(1), slabtop(1), top(1), vmstat(8).

procps-ng 2018-05-31 FREE(1)

（資料來源，終端對於 free 的說明：man free, free)

實際應用，延伸閱讀：Ubuntu 20.04 MEMTESTER 檢測 Ram