function memory_usage_mem {
  local ret="KiB Mem :"

  cat /proc/meminfo | grep MemTotal: > tmp-write
  local total=$(awk "{print \$2}" ./tmp-write)

  cat /proc/meminfo | grep MemFree: > tmp-write
  local free=$(awk "{print \$2}" ./tmp-write)

  let local used=$(( $total-$free ))

  cat /proc/meminfo | grep Buffers: > tmp-write
  local buff=$(awk "{print \$2}" ./tmp-write)
  cat /proc/meminfo | grep -w Cached: > tmp-write
  local cache=$(awk "{print \$2}" ./tmp-write)
  let local buffCache=$(( $buff+$cache ))

  echo "$ret $total total, $free free, $used used, $buffCache buff/cache"
}

function memory_usage_swap {
  local ret="KiB Swap:"

  cat /proc/meminfo | grep SwapTotal: > tmp-write
  local total=$(awk "{print \$2}" ./tmp-write)

  cat /proc/meminfo | grep SwapFree: > tmp-write
  local free=$(awk "{print \$2}" ./tmp-write)

  let local used=$(( $total-$free ))

  echo "$ret $total total, $free free, $used used."
}