1-The below command will show you ,How much RAM is installed in your computer.
[root@localhost ~]# cat /proc/meminfo
MemTotal: 28459120 kB
MemFree: 26640436 kB
MemAvailable: 27011524 kB
Buffers: 2296 kB
Cached: 673640 kB
SwapCached: 0 kB
Active: 456056 kB
Inactive: 324872 kB
Active(anon): 105620 kB
Inactive(anon): 33436 kB
Active(file): 350436 kB
Inactive(file): 291436 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 14352380 kB
SwapFree: 14352380 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 105036 kB
Mapped: 56104 kB
Shmem: 34064 kB
Slab: 127928 kB
SReclaimable: 71040 kB
SUnreclaim: 56888 kB
KernelStack: 4048 kB
PageTables: 12416 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 28581940 kB
Committed_AS: 792536 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 335348 kB
VmallocChunk: 34358943740 kB
Percpu: 2176 kB
HardwareCorrupted: 0 kB
AnonHugePages: 22528 kB
CmaTotal: 0 kB
CmaFree: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 273580 kB
DirectMap2M: 3729408 kB
DirectMap1G: 27262976 kB
[root@localhost ~]# 2-Free command will show you the total free memory amount, physically used and swap memory.
[root@localhost ~]# free -m -h
total used free shared buff/cache available
Mem: 27G 1.0G 25G 33M 729M 25G
Swap: 13G 0B 13G
[root@localhost ~]# 3-The top command is used to display memory and buffers information.
[root@localhost ~]# top
top - 16:30:29 up 22:14, 1 user, load average: 0.00, 0.01, 0.05
Tasks: 179 total, 1 running, 178 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.0 us, 0.0 sy, 0.0 ni, 99.9 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 28459120 total, 26640408 free, 1071708 used, 747004 buff/cache
KiB Swap: 14352380 total, 14352380 free, 0 used. 27011520 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
514 root 20 0 0 0 0 S 0.3 0.0 0:26.68 xfsaild/dm-0
13156 root 20 0 3722672 26872 5392 S 0.3 0.1 0:14.88 OlaServer
1 root 20 0 193828 7004 4200 S 0.0 0.0 0:07.85 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.03 kthreadd
4 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
5 root 20 0 0 0 0 S 0.0 0.0 0:08.20 kworker/u16:0
6 root 20 0 0 0 0 S 0.0 0.0 0:00.15 ksoftirqd/0
7 root rt 0 0 0 0 S 0.0 0.0 0:00.22 migration/0
8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh
9 root 20 0 0 0 0 S 0.0 0.0 0:33.35 rcu_sched
10 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 lru-add-drain
11 root rt 0 0 0 0 S 0.0 0.0 0:00.39 watchdog/0
12 root rt 0 0 0 0 S 0.0 0.0 0:00.31 watchdog/1
13 root rt 0 0 0 0 S 0.0 0.0 0:00.25 migration/1
14 root 20 0 0 0 0 S 0.0 0.0 0:00.06 ksoftirqd/1
16 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/1:0H
18 root rt 0 0 0 0 S 0.0 0.0 0:00.28 watchdog/2
[root@localhost ~]# 4-The vmstat command is used to see the memory statistics in which the user can view some additional information related to processes, block IO, traps, paging, and CPU activity.
[root@localhost ~]# vmstat -s
28459120 K total memory
1072568 K used memory
456876 K active memory
324796 K inactive memory
26639372 K free memory
2296 K buffer memory
744884 K swap cache
14352380 K total swap
0 K used swap
14352380 K free swap
35835 non-nice user cpu ticks
25 nice user cpu ticks
23867 system cpu ticks
64068895 idle cpu ticks
8760 IO-wait cpu ticks
0 IRQ cpu ticks
147 softirq cpu ticks
0 stolen cpu ticks
330917 pages paged in
594141 pages paged out
0 pages swapped in
0 pages swapped out
11900232 interrupts
11915693 CPU context switches
1648730744 boot time
15302 forks
[root@localhost ~]#
[root@localhost ~]# 5-This below command will show you the more information of memory .
[root@localhost ~]# lshw -short -C memory
H/W path Device Class Description
===============================================================
/0/1/3 memory 64KiB L1 cache
/0/1/4 memory 256KiB L2 cache
/0/1/5 memory 10MiB L3 cache
/0/2/6 memory 64KiB L1 cache
/0/2/7 memory 256KiB L2 cache
/0/2/8 memory 10MiB L3 cache
/0/6 memory 28GiB System Memory
/0/6/0 memory 8GiB DIMM DDR3 1333 MHz (0.8 ns)
/0/6/1 memory 8GiB DIMM DDR3 1333 MHz (0.8 ns)
/0/6/2 memory 4GiB DIMM DDR3 1333 MHz (0.8 ns)
/0/6/3 memory 8GiB DIMM DDR3 1333 MHz (0.8 ns)
/0/6/4 memory [empty]
/0/6/5 memory [empty]
/0/6/6 memory [empty]
/0/6/7 memory [empty]
/0/6/8 memory [empty]
/0/6/9 memory [empty]
/0/6/a memory [empty]
/0/6/b memory [empty]
/0/6/c memory [empty]
/0/6/d memory [empty]
/0/6/e memory [empty]
/0/6/f memory [empty]
/0/6/10 memory [empty]
/0/6/11 memory [empty]
/0/6/12 memory [empty]
/0/6/13 memory [empty]
/0/6/14 memory [empty]
/0/6/15 memory [empty]
/0/6/16 memory [empty]
/0/6/17 memory [empty]
/0/23 memory 128KiB BIOS
[root@localhost ~]#