How to view memory usage in Linux

To view the memory in Linux, we generally use the free command:
[Root @ scs-2 tmp] # free
Total used free shared buffers cached
Mem: 3266180 3250004 16176 0 110652 2668236
-/+ Buffers/cache: 471116 2795064
Swap: 2048276 80160 1968116

The following is an explanation of these values:
Total: total physical memory size.
Used: used.
Free: available.
Shared: The total memory Shared by multiple processes.
Buffers/cached: disk cache size.
Row 3 (-/+ buffers/cached ):
Used: used.
Free: available.
The fourth line won't be explained much.
Difference: used/free of the second row (mem) differs from used/free of the third row (-/+ buffers/cache. The difference between the two is that from the perspective of usage, the first line is from the OS perspective, because for OS, buffers/cached is used, so its available memory is 16176KB, the memory used is kb, including the + buffers + cached used by the kernel (OS) + Application (X, oracle, etc.
The third line indicates that, from the application perspective, for applications, buffers/cached is equivalent to available, because buffer/cached is designed to improve file read performance, when the application needs to use the memory, buffer/cached will be quickly recycled.
From the application perspective, the available memory = system free memory + buffers + cached.
For example:
2795064 = 16176 + 110652 + 2668236

Next, we will explain when the memory will be exchanged and by which side. When the available memory is less than the rated value, a meeting will be held for exchange.
Rating:
Cat/proc/meminfo

[Root @ scs-2 tmp] # cat/proc/meminfo
MemTotal: 3266180 kB
MemFree: 17456 kB
Buffers': 111328 kB
Cached: 2664024 kB
SwapCached: 0 kB
Active: 467236 kB
Inactive: 2644928 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 3266180 kB
LowFree: 17456 kB
SwapTotal: 2048276 kB
SwapFree: 1968116 kB
Dirty: 8 kB
Writeback: 0 kB
Mapped: 345360 kB
Slab: 112344 kB
Committed_AS: 535292 kB
PageTables: 2340 kB
VmallocTotal: 536870911 kB
VmallocUsed: 272696 kB
VmallocChunk: 536598175 kB
HugePages_Total: 0
HugePages_Free: 0
Hugepagesize: 2048 kB

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