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)

       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)

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.

       -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.

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
              ⟨procps@freelists.org⟩

SEE ALSO

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