4 ways to check size of physical memory in Linux
Introduction
In this article we will see basic commands to check the physical memory on the server under Linux. Many beginners struggle to know their system well in the context of resources such as CPU, Memory, Disks, etc. So I decided to write this small item pointing command to check the RAM on the Linux server. These commands will work in different flavors of Linux like Red Hat, CentOS, Suse, Ubuntu, Fedora, Debian etc.
1) Using free command
This command is mainly used to check the RAM and SWAP on the system. Using a different change, you can change the output byte format. Like -b for bytes, -k for kilobytes, -m for megabytes, and -g for gigabytes.
# free -b total used free shared buff/cache available Mem: 3976634368 3096838144 187990016 51572736 691806208 540106752 Swap: 4001361920 8826880 3992535040 # free -k total used free shared buff/cache available Mem: 3883432 3024204 183600 50364 675628 527488 Swap: 3907580 8620 3898960 # free -m total used free shared buff/cache available Mem: 3792 2953 179 49 659 515 Swap: 3815 8 3807 # free -g total used free shared buff/cache available Mem: 3 2 0 0 0 0 Swap: 3 0 3
2) Using /proc/meminfo file
# cat /proc/meminfo |grep Mem MemTotal: 3883432 kB MemFree: 183268 kB MemAvailable: 527276 kB
3) Using top command
# top top - 12:36:36 up 8 days, 2:58, 2 users, load average: 0.14, 0.14, 0.08 Tasks: 213 total, 1 running, 212 sleeping, 0 stopped, 0 zombie %Cpu(s): 0.2 us, 0.7 sy, 0.0 ni, 99.0 id, 0.2 wa, 0.0 hi, 0.0 si, 0.0 st KiB Mem : 3883432 total, 182356 free, 3025080 used, 675996 buff/cache KiB Swap: 3907580 total, 3898960 free, 8620 used. 526608 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2303 root 20 0 2378464 541076 7692 S 1.0 13.9 417:16.56 OpsCenterDBd
4) Using vmstat
[root@opscenter ~]# vmstat -s 3883432 K total memory 3025552 K used memory 2439780 K active memory 870348 K inactive memory 181812 K free memory 138712 K buffer memory 537356 K swap cache 3907580 K total swap 8620 K used swap 3898960 K free swap 2323674 non-nice user cpu ticks 2978 nice user cpu ticks 944914 system cpu ticks 135133743 idle cpu ticks 692582 IO-wait cpu ticks 121 IRQ cpu ticks 49623 softirq cpu ticks 0 stolen cpu ticks 1931906 pages paged in 23034525 pages paged out 377 pages swapped in 2353 pages swapped out 956323695 interrupts 2040196891 CPU context switches 1505191059 boot time 849343 forks