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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FILES | BUGS | SEE ALSO | COLOPHON |
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FREE(1) User Commands FREE(1)
free - Display amount of free and used memory in the system
free [options]
free displays the total amount of free and used physical and swap
memory in the system, as well as the buffers and caches used by the
kernel. The information is gathered by parsing /proc/meminfo. The
displayed columns are:
total Total installed memory (MemTotal and SwapTotal in
/proc/meminfo)
used Used memory (calculated as total - free - buffers - cache)
free Unused memory (MemFree and SwapFree in /proc/meminfo)
shared Memory used (mostly) by tmpfs (Shmem in /proc/meminfo)
buffers
Memory used by kernel buffers (Buffers in /proc/meminfo)
cache Memory used by the page cache and slabs (Cached and
SReclaimable in /proc/meminfo)
buff/cache
Sum of buffers and cache
available
Estimation of how much memory is available for starting new
applications, 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, available on kernels 3.14, emulated on kernels
2.6.27+, otherwise the same as free)
-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.
-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
K = kibibyte
M = mebibyte
G = gibibyte
T = tebibyte
P = 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.
-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.
-c, --count count
Display the result count times. Requires the -s option.
-l, --lohi
Show detailed low and high memory statistics.
-s, --seconds delay
Continuously display the result delay seconds apart. You may
actually specify any floating point number for delay using
either . or , for decimal point. usleep(3) is used for
microsecond resolution delay times.
--si Use kilo, mega, giga etc (power of 1000) instead of kibi,
mebi, gibi (power of 1024).
-t, --total
Display a line showing the column totals.
--help Print help.
-V, --version
Display version information.
/proc/meminfo
memory information
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
⟨procps@freelists.org⟩
ps(1), slabtop(1), top(1), vmstat(8).
This page is part of the procps-ng (/proc filesystem utilities)
project. Information about the project can be found at
⟨https://gitlab.com/procps-ng/procps⟩. If you have a bug report for
this manual page, see
⟨https://gitlab.com/procps-ng/procps/blob/master/Documentation/bugs.md⟩.
This page was obtained from the project's upstream Git repository
⟨https://gitlab.com/procps-ng/procps.git⟩ on 2018-02-02. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2018-01-13.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
procps-ng 2016-06-03 FREE(1)
Pages that refer to this page: pcp-free(1), slabtop(1), top(1), w(1), proc(5), tmpfs(5), vmstat(8)
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HTML rendering created 2018-02-02 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.
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