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
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)
Memory used by kernel buffers (Buffers in /proc/meminfo)
cache Memory used by the page cache and slabs (Cached and
SReclaimable in /proc/meminfo)
Sum of buffers and cacheavailable
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)
Display the amount of memory in bytes.
Display the amount of memory in kibibytes. This is the
Display the amount of memory in mebibytes.
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.
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
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.
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).
Display a line showing the column totals.
--help Print help.
Display version information.
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
This page was obtained from the project's upstream Git repository
⟨https://gitlab.com/procps-ng/procps.git⟩ on 2016-12-10. If you dis‐
cover 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
procps-ng 2016-06-03 FREE(1)