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.
I know that free command displays memory usages however I like to know how the option and the results when I use this command..
PLease respond ASAP
thanx... I am a newbie.. :D (1 Reply)
CentOS 2 and 3 are a 100% compatible rebuild of the RHEL 2 and 3 versions, in full compliance with RedHat's redistribution requirements. It is for people who need an enterprise class OS without the cost of certification and support.
Read more here.
I've just installed it on a spare box and it... (0 Replies)
HI
I'm a rookie in C programming and I'm working in Monta Vista Linux. I have to write a program that displays free memory. I have memtester(allready written by someone else) and now I have to type how much amount of memory tester will test and I want that memtester finds out himself how much of... (11 Replies)
Linux Kernels 2.6.16 and up provide a way to instruct the kernel to drop the page cache, inode and dentry caches on command. This tip can help free Linux memory without a reboot.
Note: This is a non-destructive operation. Dirty objects are not freeable, hence; you must run sync beforehand.
... (0 Replies)
Hi All,
Please explain me the concept of link counts when you try to view the contents of any file or directory using ls command.
-sh-3.00$ ls -lrt
total 194
drwxr-xr-x 2 root root 4096 Aug 12 2004 srv
drwxr-xr-x 2 root root 4096 Aug 12 2004 mnt
drwxr-xr-x 2 root root ... (1 Reply)
Hi,
I am facing one problem, On our Linux server Free memory decreases gradually but my java process memory does not increase.
Please any one tell, why free memory decreases gradually (1MB in approx 15 minutes).
kernel details:-
Linux linux4 2.6.9-42.ELsmp #1 SMP Wed Jul 12 23:27:17 EDT... (13 Replies)
Hello, I am not sure where to post this questions...
I have Windows XP in my home computer. I need to install Linux on
my home computer for learning purpose. Can one please recommend
any free download link to download free linux...
Any help is appreciated...
Thank you... (1 Reply)
hi- im running glassfish 3.1 on debian server and there are times where I need to start the domain when we cannot access the web application. I checked the memory and it's confusing me. Am i still ok? can you explain the below?
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME... (1 Reply)
I have two questions on Linux's free command. Below, I have provided output from my home laptop (fedora 26 ) which has 16GB Physical RAM and a production server (RHEL 7.4) which has 24GB RAM.
Question1. What exactly does the buffer/cache column say in free command's output ? buffer/cache is... (9 Replies)
Discussion started by: omega3
9 Replies
LEARN ABOUT X11R4
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 and caches used by the ker-
nel. 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)
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
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 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.
-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.
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).
procps-ng 2016-06-03 FREE(1)