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Werulz
Asked: 2013-03-07 09:16:09 +0800 CST

Get full physical Ram memory with bash

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I know some of you might find my question stupid but i need to know how much ram is installed on a centos box Yes i know it can easily be done by using the command

awk '/MemTotal/{print $2}' /proc/meminfo

However the problem is that the memory shown is not really want i need.The value shown will always be less than expected as some ram is used to load the kernel.Thus a 512 MB ram server will always show a little less than 524288 kb.

The reason while i need the full physical ram is very simple.I need to modify settings automatically on a box via my bash script. Thus if server has total 512 MB ram , one set of setting is used , if 1gb then another.....

I cannot gamble with the value return by the command above as value varies from system to system.

Any good valid option guys.......

Kind Regards

centos

2 Answers

  1. Best Answer

    Here you go... From my larger script at: Documenting server details

    # Calculate installed RAM
dmidecode -t 17 | awk '( /Size/ && $2 ~ /^[0-9]+$/ ) { x+=$2 } END{ print "\t" "Installed Ram: " x "MB"}'

    Output: Installed Ram: 28672MB (or divide by 1024)

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  2. Unfortunately, dmidecore requires root privileges.

    Another way to retrieve values, more accurate than MemTotal in /proc/meminfo : 

    $ dmesg | gawk '/BIOS-e820/&&/usable/{tot+=strtonum("0x"$4)-strtonum("0x"$2)}END{print "Total RAM: "tot/1048576" MB"}'
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