Concept of free �m command in Linux Post: 302758705

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Operating Systems Linux Red Hat Concept of free �m command in Linux Post 302758705 by sixstrings on Sunday 20th of January 2013 02:02:32 PM

01-20-2013

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Code:

             total       used       free     shared    buffers     cached
Mem:          3816       3569        247          0        118       2397
-/+ buffers/cache:       1053       2763
Swap:         3823         13       3810

ok, this is the output for my laptop.

The free command is used to display the amount of free and used memory on a system. The -m option tells free to print the output in MB.

My laptop has 4Gb currently.

Linux attempts to utilize all of the memory on the system and not leave any sitting idle, like some other operating systems have done over time. Memory will be used for the OS and applications, but the remainder will be used as "buffers and cache". The kernel will keep items in memory that are needed often or are predicted to be needed for faster access. The memory used for "buffers and cache" is available for applications or the OS to use. If required, it is quickly flushed and used.

To find the actual available memory on my system, take the last number on the Mem line (247) and add it to the last number on the Mem line (2397). So currently, I have about 3G of memory available.

Most of this information is available via the manpage and simple google searches. Take a look and you should have all of your questions answered.

sixstrings

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LEARN ABOUT DEBIAN

free

FREE(1) 							   User Commands							   FREE(1)

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 used by the kernel.  The
       shared memory column should be ignored; it is obsolete.

OPTIONS

       -b, --bytes
	      Display the amount of memory in bytes.

       -k, --kilo
	      Display the amount of memory in kilobytes.  This is the default.

       -m, --mega
	      Display the amount of memory in megabytes.

       -g, --giga
	      Display the amount of memory in gigabytes.

       --tera Display the amount of memory in terabytes.

       -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 = 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.

       -l, --lohi
	      Show detailed low and high memory statistics.

       -o, --old
	      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 number for delay, usleep(3) is
	      used for microsecond resolution delay times.

       --si   Use power of 1000 not 1024.

       -t, --total
	      Display a line showing the column totals.

       --help Print help.

       -V, --version
	      Display version information.

FILES

       /proc/meminfo
	      memory information

SEE ALSO

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

AUTHORS

       Written by Brian Edmonds.

REPORTING BUGS

       Please send bug reports to <procps@freelists.org>

procps-ng							  September 2011							   FREE(1)