Check Free Memory on Linux for Running Program

To determine the memory usage of Linux machine, you can easily google for this. But, several results may confuse you that which one is the most efficient way. After my hard finding, I found that "free" command is the best choice that fits best for checking memory usage. A free command can display the total amount of free and used physical memories, and swap memory in the system, as well as the buffers that used by the kernel.

Just type free -g, this will show you the total, used, and free memory.

free displays amount of free and used memory in the system. -g as optional, memory will be shown in Gigabytes.

For example,

             total       used       free     shared    buffers     cached

Mem:            62         54          8          1          2         45

-/+ buffers/cache:          6         56

Swap:           99          4         95

Total memory is 62 GB
Used memory is 6 GB (2nd row)
Free memory is 56 GB (2nd row)

              total        used        free      shared  buff/cache   available

Mem:             31           0          23           0           6          29

Swap:            15           0          15

Total memory is 31 GB
Free memory is 29 GB (+ buffers/cache)

To automatically determine the amount of free memory of multiple remote machines one-by-one, you may use the following code shell script which I wrote for my system.

#!/bin/bash

for i in compute-1 compute-2 compute-3 compute-4 compute-5 compute-6

do

CPU=`ssh $i "grep -c '^processor' /proc/cpuinfo"`

MEM1=`ssh $i "free -g|grep 'buffers/cache'"`

MEM2=`ssh $i "free -g|grep 'Mem'"`

echo "$i $MEM1" > mem.info.$i

echo "$i $MEM2" >> mem.info.$i

#MEMCHECK=`grep 'buffers' mem.info.$i`

if [ $(grep -c "buffers" mem.info.$i) -ne 0 ];then

FREEMEM=`awk 'FNR == 1 {print $5}' mem.info.$i`

else

FREEMEM=`awk 'FNR == 2 {print $8}' mem.info.$i`

fi

echo "Node: $i : Number of Processor = $CPU cores and Free Memory = $FREEMEM GB"

rm mem.info.$i

done

P.S. You need a password-less SSH for accessing all machines that you list in for loop.

Rangsiman Ketkaew