#!/bin/sh

SETTING=$1

if [ "$SETTING" == "off" ]; then
  echo "Turning off safe sleep"
  sudo pmset -a hibernatemode 0
  sudo nvram "use-nvramrc?"=false
  echo "Don't forget to reboot!"
  echo You are now free to remove your sleepimage file at /private/var/vm/sleepimage
elif [ "$SETTING" == "on" ]; then
  echo "Turning on safe sleep"
  sudo pmset -a hibernatemode 3
  sudo nvram "use-nvramrc?"=true
  echo "Don't forget to reboot!"
else
  echo "Usage: safesleep on | off"
fi

sudo rm /var/vm/sleepimage

As others have pointed out, this is the image file. Deleting it won't cause any problems, and has the immediate effect of disabling Safe Sleep until reboot.

I find myself doing this occasionally to free up hard drive space. A temporary solution, I know, but it gives me an instant extra 2GB free.

The only time I was able to see a password show up in the sleepimage file was after running VMWare and logging into my Vista vm. That virtual machine's password showed up twice in plain text, so if you use VMWare, that may be a cause for concern although it didn't show up alongside any other strings which would identify it as a password so without knowing what it was already I doubt if anyone but an experienced hacker could fish it out. I didn't test every single app I have installed so it's possible there may be others that aren't safe to use but in general, it appears that Apple's software is not an issue. Ideally, of course, an option to encrypt the sleepimage file along with the swapfiles would be a great addition.

BTW, my Late '08 MBP (w/7200rpm HD) updates the sleepimage file in just a few seconds when I close the lid so the time and battery issues described above shouldn't be much of an issue to users of the newer models - it's pretty seamless.

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