Free (command)

free is a UNIX command which displays the total amount of free and used physical and swap memory in the system, as well as the shared memory and buffers used by the kernel.

= Syntax =

free [-b|-k|-m] [-o] [-s delay] [-t] [-V]

Options

 * [-b|-k|-m|-g] : The -b  switch  displays  the amount of memory in bytes; the -k switch (set by default) displays it in kilobytes; the -m switch in megabytes and the -g switch in gigabytes.


 * [-t] : Displays a line containing the totals.


 * [-o] : Disables the display of a "buffer adjusted" line. Unless specified free subtracts/adds buffer memory from/to the used/free memory reports (respectively!).


 * [-s] : Activates continuous polling delay seconds apart. You may actually specify any floating point number for delay, usleep(3) is used for microsecond resolution delay times.


 * [-v]</tt> : Displays version information.

= Examples =

Invoked on a machine with 512 MB of RAM, with the "-m" switch (to give counts in megabytes):

$ free -m total      used       free     shared    buffers     cached Mem:          499        490          9          0         91        117 -/+ buffers/cache:       281        218 Swap:         964          6        958 $

= Related Commands =


 * df - Lists free space on disks
 * ps - Lists processes
 * slabtop - 'Realtime' list of slab cache information
 * top - 'Realtime' list of processes/memory/CPU states etc.