free: used value not equal to "total - free - buffers - cache"
root@intel-x86-64:~# free -m
total used free shared buff/cache available
Mem: 7827 365 7517 9 172 7462
Swap: 0 0 0
root@intel-x86-64:~# vmstat -s
8015652 K total memory
373996 K used memory
89812 K active memory
90424 K inactive memory
7697692 K free memory
43768 K buffer memory
132716 K swap cache
0 K total swap
0 K used swap
0 K free swap
20489 non-nice user cpu ticks
15 nice user cpu ticks
12781 system cpu ticks
102918297 idle cpu ticks
5017 IO-wait cpu ticks
0 IRQ cpu ticks
1170 softirq cpu ticks
0 stolen cpu ticks
0 non-nice guest cpu ticks
0 nice guest cpu ticks
106157 K paged in
102380 K paged out
0 pages swapped in
0 pages swapped out
13836884 interrupts
15601342 CPU context switches
1711702817 boot time
22774 forks
root@intel-x86-64:~# free -V
free from procps-ng 4.0.4
root@intel-x86-64:~# head -n /proc/meminfo
head: invalid number of lines: '/proc/meminfo'
root@intel-x86-64:~# head -n 10 /proc/meminfo
MemTotal: 8015652 kB
MemFree: 7711600 kB
MemAvailable: 7655572 kB
Buffers: 43776 kB
Cached: 107304 kB
SwapCached: 0 kB
Active: 89828 kB
Inactive: 90292 kB
Active(anon): 1208 kB
Inactive(anon): 37904 kB
For free and vmstat command, used != "total - free - buffers - cache"
Edited by Sandy