free

 FREE(1)                                                                                                                      User Commands                                                                                                                      FREE(1)

NAME
       free - Display amount of free and used memory in the system

SYNOPSIS
       free [options]

DESCRIPTION
       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, available on kernels 2.6.32, displayed as zero if not available)

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

       cache  Memory used by the page cache and slabs (Cached and Slab 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)

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

       -k, --kilo
              Display the amount of memory in kilobytes.  This is the default.

       -m, --mega
              Display the amount of memory in megabytes.

       -g, --giga
              Display the amount of memory in gigabytes.

       --tera Display the amount of memory in terabytes.

       -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 = kilos
                M = megas
                G = gigas
                T = teras

              If unit is missing, and you have petabyte of RAM or swap, the number is in terabytes 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 seconds
              Continuously display the result delay seconds apart.  You may actually specify any floating point number for delay, usleep(3) is used for microsecond resolution delay times.

       --si   Use power of 1000 not 1024.

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

       --help Print help.

       -V, --version
              Display version information.

FILES
       /proc/meminfo
              memory information

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

AUTHORS
       Written by Brian Edmonds.

REPORTING BUGS
       Please send bug reports to ⟨procps@freelists.org⟩

procps-ng                                                                                                                      July 2014                                                                                                                        FREE(1)