How to Check Physical Memory in Linux

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This article specifically written for showing on how to check the physical memory of an operating system which in this context, it is the physical memory of a Linux operating system. Using specific command, the amount of size possessed which is describing the total size of physical memory can be revealed. To be able to show the memory size of the physical memory attached in the server, host or workstation, it can be achieved by executing command available in the operating system :

1. cat /proc/meminfo

It is actually a command to display the content of the file named meminfo located in /proc.

user@hostname:~$ cat /proc/meminfo 
MemTotal: 8085320 kB
MemFree: 312608 kB
MemAvailable: 668600 kB
Buffers: 61944 kB
Cached: 699168 kB
SwapCached: 29040 kB
Active: 3932780 kB
Inactive: 1185576 kB
Active(anon): 3678616 kB
Inactive(anon): 977236 kB
Active(file): 254164 kB
Inactive(file): 208340 kB
Unevictable: 252 kB
Mlocked: 252 kB
SwapTotal: 8298492 kB
SwapFree: 4392368 kB
Dirty: 1400 kB
Writeback: 0 kB
AnonPages: 4348796 kB
Mapped: 2523516 kB
Shmem: 298608 kB
Slab: 216624 kB
SReclaimable: 124844 kB
SUnreclaim: 91780 kB
KernelStack: 17328 kB
PageTables: 92588 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 12341152 kB
Committed_AS: 17194540 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 0 kB
VmallocChunk: 0 kB
HardwareCorrupted: 0 kB
AnonHugePages: 425984 kB
CmaTotal: 0 kB
CmaFree: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 873216 kB
DirectMap2M: 7426048 kB
DirectMap1G: 1048576 kB

As shown in the above output, the total physical memory is stated in the MemTotal display as shown below :

MemTotal: 8085320 kB

It is 8085320 kiloByte. It is actually converted as 7,7 GB and it can be considered if it is rounded to the top as 8 GB.

2. free -m

It is a command which can be utilized to display memory size as shown below :

user@hostname:~$ free -m
total used free shared buff/cache available
Mem: 7895 6672 266 287 957 620
Swap: 8103 3810 4293

The memory size, it is shown in the total Mem : 7985.

3. top

It is a command which is useful for printing or displaying Linux processes. As shown in the following output :

top - 22:53:05 up 5 days, 1:13, 38 users, load average: 1,02, 1,18, 1,04
Tasks: 428 total,   1 running, 425 sleeping,   0 stopped,   2 zombie
%Cpu(s): 25,6 us,  9,9 sy,  0,1 ni, 57,6 id,  6,9 wa,  0,0 hi,  0,0 si,  0,0 st
KiB Mem :  8085320 total,   240348 free,  6822896 used,  1022076 buff/cache
KiB Swap:  8298492 total,  4380812 free,  3917680 used.   645204 avail Mem 

It can be seen that the KiB Mem is 8085320. There is no different between KB and KiB calcuation. It is just the notation which came up at 2000 from IEC to avoid confusion. The notation of KiB stands for KibiByte. The bi in the KibiByte is referring to the term of binary which is symbolized as in 2. It is the division of 1024 derived from the power of 2 for the size or the number can be converted into GiB.

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