Many organisations like to set or pre-set the Desktop Picture of managed Macs. There are a few options for Mac Admins.
One of the commonly used methods may break in macOS Mojave because of the new security and privacy controls for AppleEvents, also known as TCC.
Getting the Image File to the Mac
Unless you want to use one of the default macOS Desktop Picture images, you will first need to get the image file on to the client. The best way of doing that is with an installer package.
Note: installing a single image file to
/Library/Desktop Pictures is actually the first exercise/example in my book “Packaging for Apple Administrators.” Get that for a more detailed description.
I will use the same example desktop picture as in the book. You can use your own desktop picture or download
BoringBlueDesktop.png from the book’s resources.
Note: Desktop pictures on macOS can be many file formats. PNG and JPEG are most commonly used. The new dynamic desktop pictures of macOS Mojave have the
heic file extension.
First create a project folder, with a
payload folder inside:
$ mkdir -p BoringDesktop/payload
$ cd BoringDesktop
Then copy the image to the
$ cp /path/to/BoringBlueDesktop.png payload
Then you can build a pkg with
$ pkgbuild --root payload --install-location "/Library/Desktop Pictures/" --identifier com.example.BoringDesktop --version 1 BoringDesktop.pkg
The resulting pkg file will install the image file in
pkgbuild command has many options and arguments. If you get one of them slightly wrong it can lead to unexpected behavior or even break the installation. I recommend using a script to run the
pkgbuild command to avoid errors. You can find a sample build script here. Read the book for a more detailed explanation of
pkgbuild and the build script. If you prefer, you can use
munkipkg, which also simplifies and automates the process of building pkg installers.
This will provide the image in a location that the user might look for. However, for better management you want to set the desktop picture as well.
Lock Down the Desktop Picture
Once the image file is in place. You can set the desktop picture with a configuration profile. Many management systems will have an option in the ‘Restrictions’ payload where you can set the path to the desktop picture.
You can also use this custom profile:
You can learn all the ways to manage and install profiles in my other book ‘Property Lists, Preferences and Profiles for Apple Administrators’
With this configuration profile in place, the desktop picture is locked. The user can still open the Desktop preference pane but the selection will be ignored. You would need to be able to remove the profile to change the desktop picture again.
This is very useful in education and other strictly managed environments.
Suggesting a Desktop Picture
In other, less tightly managed environments, you might prefer to set an initial desktop picture, but allow the user to change it later.
The common means to do this has been to use an AppleScript command:
tell application "Finder" to set desktop picture to POSIX file "/Library/Desktop Pictures/BoringBlueDesktop.png"
If you want to run this from a shell script you would execute it with
osascript -e 'tell application "Finder" to set desktop picture to POSIX file "/Library/Desktop Pictures/Sierra.jpg"'
Note that this sets a user preference so it should be run as the user. See this post for details.
However, with macOS Mojave, Apple is introducing new Privacy and Security measures which require user approval for processes to send AppleEvents. This will put a severe limit on the use of
osascript for admin scripts.
One solution would be to whitelist your management system’s agent which allows it to send Apple Events to the Finder. This requires managing the client with a user-approved MDM.
Another solution is to avoid AppleScript and Apple Events entirely.
Here comes the
To do this, I wrote a simple command line tool which can read and set the desktop picture. Neil Martin had the brilliant idea to call it
You can read the current desktop picture with:
/Library/Desktop Pictures/High Sierra.jpg
and set the desktop picture with
$ desktoppr "/Library/Desktop Pictures/BoringBlueDesktop.png"
When you have multiple displays,
desktoppr will list all desktop pictures:
When you pass a file
desktoppr will set it as the desktop picture for all screens:
$ desktoppr /Library/Desktop Pictures/NaahNananah.jpg
You can also set a specific desktop picture for a specific screen: (index starts at zero)
$ desktoppr 0 /Library/Desktop Pictures/HotStepper.jpg
$ desktoppr 1 /Library/Desktop Pictures/LyricalGangster.jpg
$ desktoppr 2 /Library/Desktop Pictures/MrOfficer.jpg
You can get the code for
desktoppr on Github and an installer package here. The installer pkg will install
/usr/local/bin. When you want to run it from a management script it is safest to include the entire path:
/usr/local/bin/desktoppr "/Library/Desktop Pictures/BoringBlueDesktop.png"
desktoppr tool also sets user preferences, you still need to pay attention that it runs as the user.
For example, you could run
desktoppr from a LaunchAgent (deployed in
/Library/LaunchAgents so it affects all users:
This LaunchAgent will reset the Desktop Picture at every login.
If you want to set the Desktop Picture just once from a management or postinstall script (probably running as root) you can use the following to be safe:
When you find yourself building LaunchAgents or LaunchDaemons often (i.e. more than once) you should really consider using outset.
If you wanted to build an installer package that drops both the picture file and the LaunchAgent, you can do the following:
$ mkdir -p DesktopAndAgent/payload/
$ cd DesktopAndAgent
$ mkdir -p "payload/Library/Desktop Pictures/"
$ cp /path/to/BoringBlueDesktop.png "payload/Library/Desktop Pictures/"
$ mkdir -p payload/Library/LaunchAgents/
$ cp /path/to/com.scriptingosx.setdesktop.plist payload/Library/LaunchAgents
$ pkgbuild --root payload --install-location / --version 1 --identifier com.scriptingosx.desktopandagent DesktopAndAgent-1.pkg