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)

          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 cache

          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

   -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.


          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


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


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