Mention that case is important when prompting before writing.

user_tools/linux/recovery.sh

 #!/bin/sh
 #
 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # This attempts to guide linux users through the process of putting a recovery
 # image onto a removeable USB drive.
 #
 # We may not need root privileges if we have the right permissions.
@@ skipping 748 matching lines @@
   choose_drive
 
   # Be sure
   dev_desc=$(get_devinfo "$user_choice")
 fi
 echo "
 Is this the device you want to put the recovery image on?
 
   $dev_desc
 "
-prompt "You must enter 'YES' to continue: "
+prompt "You must enter 'YES' (all uppercase) to continue: "
 read tmp
 if [ "$tmp" != "YES" ]; then
   quit
 fi
 
 # Be very sure
 echo "
 
 I'm really going to erase this device. This will permanently ERASE
 whatever you may have on that drive. You won't be able to undo it.
 
   $dev_desc
 "
 
-prompt "If you're sure that's the device to use, enter 'DoIt' now: "
+prompt "If you're sure that's correct, enter 'DoIt' now (case is important): "
 read tmp
 if [ "$tmp" != "DoIt" ]; then
   quit
 fi
 echo "
 
 Installing the recovery image
 
 "
 
@@ skipping 18 matching lines @@
 prompt "Shall I remove the temporary files now? [y/n] "
 read tmp
 case $tmp in
   [Yy]*)
     cd
     \rm -rf ${WORKDIR}
     ;;
 esac
 
 exit 0