Flashes swap memory by disabling and then enabling all swap devices. It first performs a check if enough memory is available on the system. Then it syncs all dirty buffers and disables/enables swap. Motivation is to be able to quickly force swap data into memory without waiting for OS to do it. Probably, you should not need this on a healthy ser…

swapnuke.sh

#!/bin/bash

function printDebug()
{
  if [ ! -z "$debug" ]; then
    echo "$1"
  fi
}

debug="$1"

memFree=$(egrep '^MemFree:' /proc/meminfo | awk '{print $2}')
memCached=$(egrep '^Cached:' /proc/meminfo | awk '{print $2}')
memAvailable=$(expr "$memFree" + "$memCached")

swapTotal=$(egrep '^SwapTotal:' /proc/meminfo | awk '{print $2}')
swapFree=$(egrep '^SwapFree:' /proc/meminfo | awk '{print $2}')
swapUsed=$(expr "$swapTotal" - "$swapFree")

if [ ! -z "$debug" ]; then
  memTotal=$(egrep '^MemTotal' /proc/meminfo | awk '{print $2}')
  echo "Total memory: $memTotal"
  echo "Free: $memFree"
  echo "Cached: $memCached"
  echo "Available: $memAvailable"
  echo "Swapped: $swapUsed"
  echo
fi

if [ "$swapUsed" -eq "0" ]; then
  printDebug "NO NEED TO FLASH, SWAP USES 0 BYTES."
elif [ "$memAvailable" -gt "$swapUsed" ]; then
  printDebug "FLASHING SWAP..."
  sync && swapoff -a && swapon -a
  printDebug "DONE."
else
  printDebug "NOT ENOUGH FREE MEMORY."
  exit 1
fi

For more conservative use replace:

if [ "$memAvailable" -gt "$swapUsed" ]

with

if [ "$memFree" -gt "$swapUsed" ]

This "conservative option" will not affect cached disk pages.

Run as sudo:

sudo swapnuke.sh

or with more verbosity (my preference):

sudo swapnuke.sh v