Saturday, August 29, 2009

Changing the Time Machine backup interval

By default, Time Machine runs and backups up every hour. If this frequency does not suit you, you can change it. The interval is controlled in a file called "" which is here


Look for a section



I've found the editing it in a text editor makes the file go funny, so easiest of you use Property List Editor from the Developer Tools kit. Its in the applications / utilities folder

Update: you can also change the interval from the command line:

    sudo defaults write /System/Library/LaunchDaemons/ StartInterval -int 7200

makes the intervals 2 hours

Wednesday, August 26, 2009

Editing .gpx files

I'm using my iPhone 3Gs and the Trails application as a GPS logger. The problem is that if GPS becomes unavailable, Trails records the cell tower location instead. This means that data points are bogus, and you get results like you are hiking and your reported is over 5000 mph. ;-)

So I've been looking for a way to remove these bogus data points. They are easy enough to spot: if you are at any kind of altitude they have always record zero ele; also even after a few minutes they do not move.

After much searching, I've found gpsWrite which can cut bogus data points. It can open and save .gpx files.

The only minor problem is that when it writes the file it puts no spaces or blank lines between the xml entries which makes it very hard to read the file.

I looked on the web site to see if there was a way to contact the developer, but there is no 'contact / email' section. If this was fixed I would consider registering for the $12.95.

Saturday, August 22, 2009

AP Grapher - forgetting SSIDs

AP Grapher for Apple OSX is a great utility for scanning for wireless points, SSIDs and, for your own base stations, what security they are running.

But after a while it accumulates lots of old stations. You can reset the list and have it forget them and start again by deleting or renaming the file

~/Library/Application Support/AP Grapher/basestations.plist.

Restart AP Grapher and it'll start from fresh

Tuesday, August 11, 2009

Resetting Keychain Login Password

If you've ever lost your OSX password and had the admin reset it, or had to start from the DVD to reset your password, you'll know that you also lose the Keychain Login Password. So every time you try to do something thats requires a password, or something saved, you get asked for your keychain password.

Rather tedious.

This is how to reset it:
  1. Go to Applications > utilities > Keychain Access
  2. From the Edit menu, choose Keychain List
  3. Delete the "login" keychain.
Job done!

Thursday, August 6, 2009

Using Remote Disc on non MacBook Air

If you have a Mac that doesn't have an optical drive, or your optical drive has failed, or for whatever reason your OSX machine doesn't have an optical drive, you can access a CD / DVD read-only on another OSX or windoze windows machine.

First setup the share.

On a Mac go to System Preferences > Sharing and select "DVD or CD Sharing".

For windows follow the instructions.

If your OSX machine is not a MacBook air, to access Remote Disc you need to run two commands in Terminal:

defaults write EnableODiskBrowsing -bool true
defaults write ODSSupported -bool true

Then, restart.

To use Remote Disc

select it in the Finder.

If, on the machine sharing out the Disc, you have selected the "ask" you'll need to click "Ask to use...". While this is kind of good for security, though no username / password is required, its tedious because every time you click on the Remote Disc you have to ask, and the request has to be accepted

after you click on "Ask to use.." it goes off and asks for permission

when the permission is granted, you then have access.

The dics shows up in the finder. This is only an example... you cannot play a commercial DVD, burn a CD, browse or play music remotely. You should be able to play non-commercial ones over Remote Disc..

Tuesday, August 4, 2009

Dahon Jack Review

Now for something a little different... a review of the Dahon Jack.

This is my third Dahon folder. My first was a Curve, the second a Mu, and now the Jack.

The reason I switched from the Curve to the Mu was that the Curve with it 16" wheels and 3 speed hub simply wasn't fast enough! The Mu was slightly lighter, had the same fold time, but with the 20" wheels and the 8 speeds it was faster and nicer to ride. Also the Mu had better equipment: better brakes, nicer saddle, comfyier grips. Same uber fast fold time.

But, at about 100Kg I am at the weight limit of the Mu, and the combination of this, the less than 100% robust steering and rather lumpy London roads meant that I was not very confident in the longevity of the Mu. Also I found the adjustment mechanism for the folder steering very hard to work correctly.

Looking around for another bike that was still super fast to fold, but didn't have the weaknesses of the Mu, first I looked at the Dahon Cadenza. Great looking bike, excellent equipment, but, you need a tool to be able to fold and unfold. As I need to take the bike on trains and the Tube, this was a show stopper. If I went back to hardly ever needing to travel with a bike, or, I wanted a bike to, say, take on holiday, the Cadenza would be ideal.

So I settled on the Jack. Its robust, acceptable light, has 7 gears and it is generally competent.

  • as rigid as a regular bike
  • the stand under the bottom bracket makes parking it at work or on the train easy
  • easy to ride

  • the equipment is a bit cheap - I was prepared to spend more on better equipment
  • the gearing is a little short for my taste - I am going to investigate getting a larger chainwheel
  • no mudguards - I have some on order
but these are fairly minor criticisms.

Monday, August 3, 2009

Paintbrush - a word of thanks!

Just wanted to say what a great piece of software Painbrush for Mac is.

As the web page says "When Apple released the original Macintosh in 1984, they included two applications: MacWrite and MacPaint. Twenty-five years later, every Mac still includes a basic text editor in TextEdit, but a simple paint program is a thing of the past."

Fast to load, easy to operate. What more can you ask. Oh free you ask. Yes is it.

I've donated to show my thanks!


Saturday, August 1, 2009

Deep Sleep HIbernate on G4 PowerBook and iBook

Howto enable Deep Sleep / Hibernate on G4 PowerBook and iBook.

Was looking for how to do this, and found the original source is not around anymore. Found an archive version from

1. Apply Safe Sleep Property

To summarize, new PowerBooks have the “has-safe-sleep” property. To apply this property to your Mac, something needs to be run in Open Firmware at boot. In the Terminal enter the folling, hitting return at the end of each line:

sudo nvram nvramrc='" /" select-dev
" msh" encode-string " has-safe-sleep" property
sudo nvram "use-nvramrc?"=true

In a Terminal shell it should look as follow:

computer:~ User$ sudo nvram nvramrc='" /" select-dev
> " msh" encode-string " has-safe-sleep" property
> unselect
> '
computer:~ User$ sudo nvram "use-nvramrc?"=true

The Mac must be restarted to set the changes.

2. Allow Hibernate Mode

To continue, you must have at least as much free disk space as physical memory , plus 750MB. To enable Sleep Safe, in the Terminal enter:

sudo pmset -a hibernatemode 3

This should create the file /var/vm/sleepimage.

If (and only if) you have secure virtual memory enabled, enter 7 (rather than 3) to disable encrypted hibernation. Encrypted Safe Sleep does not yet work.

When your Mac is set to sleep, it will now enter regular Sleep mode first (consuming minimal power). It will only enter Safe-Sleep if the battery is very low on power, or is unpluged. If you prefer to skip regular sleep, and use Safe Sleep mode instead (note: it takes a few seconds more to sleep and wake-up) enter:

sudo pmset -a hibernatemode 1

Enter 5 (rather than 1) with secure virtual memory.

To disable Safe Sleep:

sudo pmset -a hibernatemode 0

The Mac does not need to be restarted to set the changes to hibernate mode.

What is secure virtual memory?
Secure virtual memory is a software feature that encrypts your swap-files and sleep-image. The option is found in the Security pane in System Preferences. It is not enabled by default, and is does not need to be enabled to use Safe Sleep. In-fact, encrypted Safe Sleep appears to not yet work.

3. Verify Sleeping

Put the Mac to sleep and wait for the light to start pulsing. Wait a few more seconds. Wake it normally (by hitting the space bar for example).

Open Console and view system.log, or simply open the file /var/log/system.log. Look for a line indicating that the process worked. It is similar to:

Nov 11 12:15:33 computername kernel[0]: System SafeSleep

4. Verify Safe Sleep

Now attempt to actually Safe Sleep for real. Put the Mac to Sleep, and wait for the light to start pulsing. Remove the power-source plug and the battery. Wait for the light to stop pulsing and turn off, which may take a a couple of minutes. Your Mac should now be in Safe Sleep mode. Plug the power back in and add the battery. Start-up. It should show the previous saved desktop (blurred and in grayscale) along with a progress bar as pictured above. The system should be back to the way you left it.

Safety: To be safe, don’t use FireWire target disk mode on a Mac that is in Safe Sleep/hibernation, since you may end up with filesystem corruption.


You may have problems with a bad hibernate images, which may repeatedly kernel panic. Try restarting which will start the image again. It may work. It may not, and repeatedly fail. This can happen if you don’t set “hibernatemode” properly when using secure virtual memory. If a bad hibernate image keeps booting then crashing reboot the mac holding down Command-Option-O-F to get in to Open Firmware. Type:

setenv boot-image

Hit return, then enter:


Disable Safe Sleep

To disable Safe Sleep enter in the Terminal:

sudo pmset -a hibernatemode 0

No need to restart.

For a more full undo, disable all nvramrc variables:

sudo nvram "use-nvramrc?"=false

Enter password, then restart.


Safe sleep isn’t perfect yet for all users. Safe Sleep should really only serve as a backup to regular Sleep, for times when the laptop battery is depleted or you need to unplug and move your desktop.

You should not use Safe Sleep as a replacement to regular Sleep. Regular Sleep is much faster, and uses very little power.It take about 15 seconds to enter Safe Sleep, and about 40 seconds to wake-up from it. That is much longer than the 2 seconds it takes for regular Sleep and wake-up.

Safe Sleep seems very promising though and it will be interesting to see if Apple officially supports it with older laptops.

[Updated on Nov 14, 2005 with wording changes and info on secure virtual ram.] [Updated on Nov 15, 2005 with warning on using target disk mode.]