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Bing wallpaper on a Mac

I use Bing Desktop on my Windows machine at the office exclusively for the wallpaper images. At home I have a Mac and I wanted an easy way to get the same wallpapers on my Mac. After some online searching I couldn’t find a solution that I was pleased with, so I wrote my own (below).

#!/usr/bin/env bash

# create our directory tree
mkdir -p ~/Pictures/Bing/Archive

# change to our destination directory
cd ~/Pictures/Bing

# today's image
URL=$(curl -s | grep url | sed -e "s/.*url=\"\([^\"]*\).*/\1/" | head -1)
URLSIG=$(md5 -q -s ${URL})
TODAY="$(date +%Y-%m-%d)_${URLSIG}.jpg"

# exit if we already have today's image
if [[ $(find . -type f -name "*${URLSIG}*") ]];
exit 0

# archive old images
mv ./*.jpg Archive/

# download latest image
curl ${URL} -s -o ${TODAY}

# the next time OS X changes the wallpaper it should find the the new file and update the wallpaper
# assumes OS X is configured to rotate the wallpaper from ~/Pictures/Bing at some interval
# i run this script on the 59th minute of every hour and configured OS X to change the wallpaper every hour

The script only downloads the latest image in the Bing Images feed if a file isn’t found with the same URL signature (MD5 hash) in the destination directory tree. If the script decides it needs to download a new file, it first archives the current file and then downloads the new file. The archive step can be commented out if you would like to keep prior wallpapers in the rotation. My preference is to always use the latest wallpaper.

To run the script save it anywhere, like your home directory, and make it executable:

chmod +x

Then you can set up a crontab or run it manually. I set up a crontab for the 59th minute of each hour to run the script

59 * * * * ~/

Finally, I configured OS X to change the wallpaper every hour from the destination directory.

I published this script to GitHub here.

Pause, not Suspend virtual machines in ESX

I recently had to perform a core storage upgrade affecting the NFS backed datastore of some ESX servers I manage. We wanted to avoid shutting down some virtual machines and found this gem online.

This article illustrates the [unsupported] ability to pause a VM by sending the VM process a kill -STOP signal and resume by sending a kill -CONT signal. We needed to do this because we didn’t want the VM doing any IO while the storage was unavailable to the ESX server.

The article was written for ESXi and I have an ESX environment so I didn’t use their approach, instead my one liners to pause and resume *all* the VMs on the host looked like this:

for vm in `ps -ef | grep vmware-vmx | grep -v grep | awk '{ print $2; }'`; do kill -STOP $vm; done

for vm in `ps -ef | grep vmware-vmx | grep -v grep | awk '{ print $2; }'`; do kill -CONT $vm; done

Useful, even if the use case is very esoteric.

Migrating Windows 7 to a machine with a different storage controller

I recently had to migrate a Windows 7 installation from a Precision T3500 to the newer T3600. Normally this would not be a problem, however at the time of the migration I did not realize the storage controller on the T3600 was different than its predecessor and Windows doesn’t have a built-in driver for it. This meant that when the time came to boot the system on the new hardware, Windows could not boot.

To save you time, the easy fix is: Prior to migrating the hard drive, install the storage controller driver and drop the other drivers (like ethernet and usb 3.0) on the c: drive to install after you boot into the new hardware.

If, like me, it is now too late to go back or you’ve already taken the step, you will need to install the driver after the fact following these steps.

1. Find the correct driver for your storage controller and copy it to a flash drive or similar.
2. Boot into Startup Recovery (Windows should do this for you automatically the second time you try booting the system as it won’t be able to find the partition and fail booting the first time).
3. Click on “Load Driver” from the System Recovery Options window and load the driver you have on your flash drive. This will now allow the Windows installation to be found.
4. Click on the “Use recovery tools…” radio button and then click on “Next” to begin the automatic repair operation and immediately cancel it as it will take a long time and may not fix anything. After confirming you want to cancel, look for the View advanced options for system recovery and support link in the Windows cannot repair this computer automatically dialog.
5. In the Choose a recovery tool dialog, click on Open a Command Prompt link to open a command prompt and then run diskpart.exe. Enter the command list vol to get the drive letter for your flash drive and your Windows installation. Exit diskpart once you obtain this information.
6. Find the path to the driver on your flash drive, you only need the directory path containing the files.
7. Type in dism.exe /image:<windows_drive_letter> /add-driver /driver:<path_to_driver> /recurse to install the drivers.
8. Once the drivers are installed, reboot the system by typing wpeutil reboot

You should now be able to boot into Windows to complete the migration.

January post

My customary 2013 January post

The host command

One routinely needs to look up the name or IP of a machine or other device on the network. A popular way of finding out an IP address from a hostname is with the ping command, however, this only works if you need the IP address, not if you need the host name.

There are a number of tools that leverage DNS, such as nslookup, dig and host. They each have their uses which happen to be very similar. The three tools do essentially the same thing, however, it should be noted that nslookup is mostly deprecated in favor of dig and host. My personal preference between these tools is host due to its terse output.

These tools are all DNS clients, and as such they will query whatever DNS resolvers are defined on your network before proceeding to query hosts files etc, note that you can also specify the resolver you want to use via a command line argument to the tools.

So with this information, if I want to look up a machine’s hostname when only armed with it’s IP, as long there is a valid reverse DNS zone that host can query the command would look like this

$ host domain name pointer fw.domain.local.

or if I am looking for an IP or any information from a CNAME or A record (say, a hostname)

$ host fw
fw.domain.local has address

$ host intranet
intranet.domain.local is an alias for www1.domain.local.
www1.domain.local has address

Note that in the case of intranet it resolves it as an alias (CNAME) and then proceeds to resolve the actual host record as well giving me the IP address as well.

This is one of my favorite tools included with the dnsutils Linux package or Cygwin for Windows.

Optimal Gmail experience on the iPhone

Google recently announced that they are discontinuing EAS for new non Apps accounts (ie, Gmail).

Google’s reasons? Who knows, it’s likely a combination of sticking it to the man or simply wanting to pursue open standards where applicable.

Affected platforms and workarounds (that I know about)

  • Android owners: not affected, Google sync works on Android devices out of the box
  • iOS users: go download the official (and awesome!) Gmail app for mail. For calendar sync go to your phone’s Settings and add a new Gmail account enabling Calendar sync when asked (you can also enable mail sync but due to the Gmail app you don’t really have to). Finally, for contact sync, add a new account of type “Other” and choose “Add a CardDav account”. Use as the server name and your Gmail credentials to finalize the setup. I’m hoping that in a future iOS release Apple will add a Contact slider like it has for Calendar sync in the Gmail account type properties.
  • Windows Phone 8: who uses this?, but seriously, I don’t know… yet. If I had to guess, I’d say the cleanest solution would be for Microsoft to start supporting CardDAV and CalDAV in addition to IMAP in their mobile mail application. At least then, Windows Phone users would have a “supported” configuration. I’m keeping an eye out for what Redmond decides to do other than Twitter blast the Google PR execs.

December 2012

The year has come and gone… many things happened this year, however let’s see if I can keep up with myself and post at least one useful nugget a few times a week…or dare I say: daily?!

Keeping up with the January posts each year

I’ll try to post more this year, however just wanted to keep the tradition alive and get in my January post this year.


Customizing Windows 7’s logon screen and user picture with Group Policy


How can we get our logo on here?

Is what my boss’s boss asked me right after I installed Windows 7 on his machine. Being one of the first 5 people in the office with a Windows 7 workstation and a pioneer in my rollout, I quickly told him: of course! … then I got to work on the best way to accomplish that.

Prep work

The first thing I did was create a location on my network accessible by all authenticated users, this is where the custom artwork will live.

The user picture

Is a 128×128 pixel bitmap, which our logo happens to fit nicely into, so I grabbed the graphical part of our logo and shrunk it to fit into a square 128×128 pixel bitmap, saved it to its home on the network and moved on to the background images.

The background images

Windows 7 supports multiple files, a default file called backgroundDefault.jpg and 12 other files with the resolutions appended to the default name (ie. background1920x1200.jpg). The system will determine which file to use (if the file with your screen resolution exists) in %windir%\system32\oobe\info\backgrounds (can be created if it doesn’t exist). If you omit an explicitly sized file for a screen resolution, the default file will be stretched to fit your resolution. One final note, images must be less than 256kb in size. The list of supported resolutions is below:



Once I had the background images for the resolutions that we have in the office, I saved those files to a subfolder in the network location I created previously and launched the Group Policy Management console.

Group Policies

Now that we have our resource files on the network we just need to tell Group Policy what to do.

Create a new Group Policy Object in an OU that contains the computers you want to customize and make the following changes to the policy.

From the Computer Configuration –> Policies –> Administrative Templates: enable Apply the default user logon picture to all users (from Control Panel/User Accounts) and enable Always use custom logon background (from System/Logon).

From Computer Configuration –> Preferences –> Windows Settings –> Files: add a new File item with a target path of %programdata%\Microsoft\User Account Pictures\user.bmp, from General make the source the 128×128 user picture we saved on the network (use its UNC path), you can leave everything else with its default setting but make its Action Replace.

From Computer Configuration –> Preferences –> Windows Settings –> Files: add a new File item with a target path of %systemroot%\System32\oobe\info\backgrounds\ (make note of the trailing \, it is required to indicate the target is a directory, not a file), from General set the source file(s) to be the directory we saved (use its UNC path) but append \* to the filepath, to indicate that you want to copy all the files from this subdirectory to the target. As with the previous item, you can leave everything else with its default values but make its Action Replace.

From User Configuration, leave everything blank.

Once done, your output should look like the screenshots below (replacing \\domain.local with your own domain’s FQDN):



Further reading: Rafael Rivera’s Within Windows post was a valuable point of reference for this project.

Saved Windows Credentials on Windows 7 Home Premium

The problem

I have a few Windows 7 Home Premium machines at home which I network together. I don’t use HomeGroups yet, and may not in the near future but I do keep some resources on the network that each machine has to access. Windows 7 Home Premium (and lower) does not remember credentials for other Windows machines (if you click the “Remember this password” checkbox in many authentication dialogs, Windows will not remember them and re-use them on next logon) so this becomes a problem when you are using service accounts to access shared media across machines (I don’t have an Active Directory domain at home).

The workaround/solution

My old solution was to create a service account on the machines needing to access the shared resources and hide the service account from view on each machine.

My new solution is to use the Windows Credentials Manager (in the Start Menu, search for “Manage Windows Credentials”). This will bring you to the Operating System’s Credential Manager, where you can Add a Windows credential. From this window, type in the server name and local username and password that authenticates on that server (like your service account) and click on OK.

Windows will now use those credentials whenever it tries to authenticate against that machine.

All you need to do now is to remember to change the password here whenever you change it on your servers for your service accounts.