free - Display amount of free and used memory in the system
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
total Total installed memory (MemTotal and SwapTotal in /proc/meminfo)
used Used memory (calculated as total - free)
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)
Memory used by kernel buffers (Buffers in /proc/meminfo)
cached Memory used by the page cache (calculated as Cached - Shmem in /proc/meminfo - the Cached value is
actually the sum of page cache and tmpfs memory)
Display the amount of memory in bytes.
Display the amount of memory in kilobytes. This is the default.
Display the amount of memory in megabytes.
Display the amount of memory in gigabytes.
--tera Display the amount of memory in terabytes.
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.
-c, --count count
Display the result count times. Requires the -s option.
Show detailed low and high memory statistics.
Display the output in old format, the only difference being this option will disable the display of the
"buffer adjusted" line.
-s, --seconds seconds
Continuously display the result delay seconds apart. You may actually specify any floating point num-
ber for delay, usleep(3) is used for microsecond resolution delay times.
--si Use power of 1000 not 1024.
Display a line showing the column totals.
--help Print help.
Display version information.