Linux command:
ps -aux | sort -k6nr | head -n 100 | awk '{sum+=$6} END {print sum}'
Explanation: Use ps to list the processes, and use sort to sort, -k specifies the sort position, here is the 6th field, nr is sorted in reverse order by numerical value,
The following head is to calculate 100, and finally use awk to process, add the values of the sixth column, and finally output uniformly to get the memory usage of the first 100 programs
Commonly used is free
free -m
total used free shared buffers cached
Mem: 7970 7803 167 0 28 2194
-/+ buffers/cache: 5580 2390
Swap: 511 487 24
Explanation: free is a command for statistical viewing of memory. The -m parameter is the conversion bit in M.
The above fields represent:
total: total physical memory used: used physical memory (usually refers to the memory used by the program) shared: (each program shares memory)
buffer: only cache, mainly for directories cached: system cache, related to the number of open files, mainly used to improve file read and write speed
Note: The used memory includes cached, which means that the actual memory used by the program is used - cached. When needed, cached will be automatically released and become available.
More detailed memory usage, linux command:
$cat /proc/meminfo MemTotal: 8162240 kB MemFree: 169352 kB MemAvailable: 2489860 kB Buffers: 31932 kB Cached: 2235540 kB SwapCached: 3516 kB Active: 5588576 kB Inactive: 2106312 kB Active(anon): 5401856 kB Inactive(anon): 25620 kB Active(file): 186720 kB Inactive(file): 2080692 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 524284 kB SwapFree: 25572 kB Dirty: 296 kB Writeback: 0 kB AnonPages: 5424008 KB Mapped: 39836 kB Shmem: 16 kB Slab: 187364 kB SReclaimable: 155748 kB SUnreclaim: 31616 kB KernelStack: 8352 kB PageTables: 27088 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 4605404 kB Committed_AS: 7188828 kB VmallocTotal: 34359738367 kB VmallocUsed: 0 kB VmallocChunk: 0 kB DirectMap4k: 16248 kB DirectMap2M: 3129344 kB DirectMap1G: 7340032 kB