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Top Forums UNIX for Beginners Questions & Answers Interpreting Linux's free command output Post 303010964 by omega3 on Thursday 11th of January 2018 05:32:04 AM
Old 01-11-2018
Interpreting Linux's free command output

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 only 1GB in my home laptop but it is 18GB in production server below.


Question2. To know the free RAM available to the system, Can I trust the 'available' column rather than the 'free' column ?
In my home laptop, the 'free' column shows 13GB and available shows 14GB
But, in my production server, when the free command shows just 2GB , the available command shows 9 GB


My Home Laptop with 16 GB RAM (Fedora 26)
Code:
[sysadmin@keithspc ~]$ cat /etc/redhat-release
Fedora release 26 (Twenty Six)
[sysadmin@keithspc ~]$
[sysadmin@keithspc ~]$ uname -a
Linux keithspc 4.12.8-300.fc26.x86_64 #1 SMP Thu Aug 17 15:30:20 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
[sysadmin@keithspc ~]$
[sysadmin@keithspc ~]$ free -h
              total        used        free      shared  buff/cache   available
Mem:            15G        854M         13G        385M        1.0G         14G
Swap:          7.8G          0B        7.8G
[sysadmin@keithspc ~]$
[sysadmin@keithspc ~]$ free -m
              total        used        free      shared  buff/cache   available
Mem:          15939         854       14073         385        1011       14362
Swap:          8034           0        8034
[sysadmin@keithspc ~]$

A production Server (VM) with 24GB RAM (RHEL 7.4)
Code:
[root@manhprod187 ~]# cat /etc/redhat-release
Red Hat Enterprise Linux Server release 7.4 (Maipo)
[root@manhprod187 ~]#
[root@manhprod187 ~]# uname -a
Linux manhprod187 3.10.0-693.5.2.el7.x86_64 #1 SMP Fri Oct 13 10:46:25 EDT 2017 x86_64 x86_64 x86_64 GNU/Linux
[root@manhprod187 ~]#
[root@manhprod187 ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:            23G        3.3G        2.0G         10G         18G        9.0G
Swap:          2.0G        1.4G        674M
[root@manhprod187 ~]#
[root@manhprod187 ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:          23948        3471        2002       11006       18473        9194
Swap:          2063        1389         674
[root@manhprod187 ~]#

 

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Linux::Distribution::Packages(3pm)			User Contributed Perl Documentation			Linux::Distribution::Packages(3pm)

NAME
Linux::Distribution::Packages - list all packages on various Linux distributions SYNOPSIS
use Linux::Distribution::Packages qw(distribution_packages distribution_write); $linux = new Linux::Distribution::Packages({'format' => 'csv', 'output_file' => 'packages.csv'}); $linux->distribution_write(); # Or you can (re)set the options when you write. $linux->distribution_write({'format' => 'xml', 'output_file' => 'packages.xml'}); # If you want to reload the package data $linux->distribution_packages(); DESCRIPTION
This is a simple module that uses Linux::Distribution to guess the linux distribution and then uses the correct commands to list all the packages on the system and then output them in one of three formats: native, csv, and xml. Distributions currently working: debian, ubuntu, fedora, redhat, suse, gentoo, slackware, redflag. The module inherits from Linux::Distribution, so can also use its calls. EXPORT None by default. TODO
* Add the capability to correctly get packages for all recognized distributions. * Seperate out parsing from writing. Parse data to hash and give access to hash. Then write the formatted data from the hash. AUTHORS
Judith Lebzelter, <judith@osdl.org> Alberto Re, <alberto@accidia.net> COPYRIGHT AND LICENSE
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.5 or, at your option, any later version of Perl 5 you may have available. perl v5.10.1 2006-04-19 Linux::Distribution::Packages(3pm)
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