FREE(1)

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

SYNOPSIS
free [option ...]

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 usable memory (MemTotal and SwapTotal in /proc/meminfo). This includes the physical and swap memory minus a few reserved bits and kernel binary code.

used
    Used or unavailable memory (calculated as total - available)

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
      Ki = kibibyte
      Mi = mebibyte
      Gi = gibibyte
      Ti = tebibyte
      Pi = 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.

-L, --line
    Show output on a single line, often used with the -s option to show memory statistics repeatedly.

-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.

-v, --committed
    Display a line showing the memory commit limit and amount of committed/uncommitted memory. The total column on this line will display the memory commit limit. This line is relevant if memory overcommit is disabled.

--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).