#!/bin/sh
# Script by Ypnose - http://ywstd.fr

# /proc/meminfo         = vmstat -s     (procps-ng sysinfo.c)
# MemTotal              = total memory  (kb_main_total)
# MemFree               = free memory   (kb_main_free)
# Buffers               = buffer memory (kb_main_buffers)
# Cached                =               (kb_page_cache)
# SReclaimable          =               (kb_slab_reclaimable)
# Cached + SReclaimable = swap cache    (kb_main_cached)
# kb_main_used = mem_used = kb_main_total - kb_main_free - kb_main_cached - kb_main_buffers

printf "          TOTAL  USED  FREE  BUF  CACHE\n"

# free command output
# -w: wide mode
# Mem: kb_main_total  kb_main_used  kb_main_free  kb_main_buffers  kb_main_cached
free -wm | awk '
	/^Mem/{ printf("free:     %d  %d  %d  %d  %d\n", $2, $3, $4, $6, $7) }
'

# vmstat command output
vmstat -s -SM | awk '
	BEGIN { printf("vmstat:   ") }
	/(total|used|free|buffer) memory|swap cache/{ printf("%d  ", $1) }
	END { printf("\n") }
'

# /proc/meminfo output
awk '
	/^MemTotal:/ { memtot = $2 / 1024; next }
	/^MemFree:/ { memfree = $2 / 1024; next }
	/^Buffers:/ { membuff = $2 / 1024; next }
	/^Cached:/ { memcach = $2 / 1024; next }
	/^SReclaimable:/ { memrecl = $2 / 1024; next }
	{ memused = memtot - memfree - membuff - memcach - memrecl }
	{ memboth = memcach - memrecl }
	{ membc = membuff + memboth }
	END { printf "meminfo:  %d  %d  %d  %d  %d     BC:%d\n",
		memtot, memused, memfree, membuff, memboth, membc }
' /proc/meminfo