Avoiding AppleScript Security and Privacy Requests

AppleScript on macOS is a useful tool for pro users and administrators alike. Even though it probably is not (and shouldn’t be) the first tool of choice for many tasks, there are some tasks that AppleScript makes very simple. Because of this it should be a part of your ‘MacAdmin Toolbelt.’

AppleScript’s strength lies in inter-application communication. With AppleEvents (or AppleScript commands) you can often retrieve valuable information from other applications that would be difficult or even impossible, to get any other way. With AppleScript, you may even be able to create and change data in the target applications.

If you are in any way security and privacy minded this should raise your hairs. Up to macOS 10.13 High Sierra, any non-sandboxed app could use AppleScript and AppleEvents to gather all kinds of personal and private data from various script-enabled apps and services. It could even use script-enabled apps like Mail to create and send email in your name.

Since macOS Mojave, the Security and Privacy controls restricts sending and receiving AppleEvents. A given process can only send events to a different process with user approval. Users can manage the inter-application approvals in the Privacy tab of the Security & Privacy preference pane.

MacAdmins have the option of pre-approving inter-application events with a PPPC (Privacy Preferences Policy Control) configuration profile that is pushed from a DEP-enrolled or user-approved MDM.

Privacy approval

You can trigger the security approval from Terminal when you send an event from the shell to another process with osascript:

> osascript -e 'tell application "Finder" to get POSIX path of ((target of Finder window 1) as alias)'

When you run this command from Terminal, you will likely get this prompt:

You will not get this prompt when you have approved or rejected the Terminal app to send events to this particular target application before. You can check the permissions granted by the user in the Automation section of Privacy tab in the Security & Privacy pane of System Preferences.

For any given source/target application combination, the prompt will only be shown once. When the user approves the privilege (“OK” button), future events will just be allowed.

When the user rejects the connection (“Don’t Allow” button), this event and future events will be rejected without further prompts. The osascript will fail and the AppleScript will return an error –1743.

> osascript -e 'tell application "Finder" to get POSIX path of ((target of Finder window 1) as alias)'
79:84: execution error: Not authorized to send Apple events to Finder. (-1743)

If you want to get the approval dialogs again, you can reset the state of the source application (Terminal) with the tccutil command:

> tccutil reset AppleEvents com.apple.Terminal

This will remove the Terminal application and all target applications for it from the Automation (AppleEvents) area in the Privacy pane and show dialogs for every new request going forward. This can be very useful during testing.

Dealing with rejection

You should write your code in a ways that it fails gracefully when access is not granted. in this case osascript will return an error:

if ! osascript -e ' tell app "Finder" to return POSIX path of ((target of Finder window 1) as alias)'
then
 echo "osascript encountered an error"
 exit 1
fi

However, osascript will return errors for all kind of failures with no easy way to distinguish between them. As an example, the above will also fail when there are no Finder windows open.

If you want to distinguish AppleScript errors, you need to do so in the the AppleScript code:

if ! osascript -s o <<EndOfScript
    tell application "Finder"
        try
            set c to (count of Finder windows)
        on error message number -1743
            error "Privacy settings prevent access to Finder"
        end try
        
        if c is 0 then
            return POSIX path of (desktop as alias)
        else
            return POSIX path of ((target of Finder window 1) as alias)
        end if
    end tell
EndOfScript
then
    echo "osascript failed"
fi

Note: the -s o option of osascript makes it print AppleScript errors to standard out rather than standard error, which can be useful to find the errors in logs of management systems.

Note 2: when you are running osascript from management and installation scripts (which run as the root user) you need to run them as the current user to avoid problems.

Avoiding Privacy prompts

So, we know of one way to deal with the privacy prompts. Ideally, you would want to avoid them entirely. While this is not always possible, there are a few strategies that can work.

Don’t send to other Processes

In past versions of Mac OS X (I use this name intentionally, it’s that long ago.), scripts that showed dialogs might not display on the highest window layer. In other words, the dialog was lost behind the currently active windows. To avoid “lost” dialogs, it became best practice to send the display dialog command (and similar) to a process that had just received an activate command as well:

tell application "Finder"
    activate
    display dialog "Hello, World!"
end tell

As an alternative for Finder, the System Events process is often used as well. Jamf MacAdmins often used “Self Service.” This had the added bonus, that the dialog looks as if it comes from the Finder or Self Service, including the bouncing dock icon.

Over time, even though the underlying problem with hidden dialog has been fixed, this practice has persisted. You often even see AppleScript code use this with commands other than user interaction, where it wouldn’t have made sense in the first place. With the privacy restrictions in macOS Mojave, this practice has become actively trouble some, as you are sending the display dialog (or other) command to a separate process. The process running this script will require approval to send events to “System Events.”

osascript <<EndOfScript
    tell application "System Events"
        activate
        display dialog "Hello, World!"
    end tell
EndOfScript

In current versions of macOS, you can just use display dialog and may other commands without an enclosing tell block. Since your AppleScript code isn’t sending events to another process, no privacy approval is provided. This code has the same effect as above, but does not trigger an approval request.

osascript <<EndOfScript
    display dialog "Hello, World!"
EndOfScript

To determine whether an AppleScript command requires a tell block, you have to check where it is coming from. Many AppleScript commands that are useful to MacAdmins are contained in the ‘StandardAdditions’ scripting extension. Scripting extensions, as the name implies, extend the functionality of AppleScript without requiring their own process.

The useful commands in the Standard Additions extension include:

  • user interaction: choose file/folder/from list, display dialog/alert/notification
  • file commands: mount volume
  • clipboard commands: get the clipboard, set the clipboard to
  • sound control: set volume, get volume settings
  • system info

When your script uses only these commands, make sure they are not contained in tell blocks. This will avoid unnecessary prompts for access approval.

Exempt AppleScript commands

Some AppleScript commands are treated differently and will not trigger privacy approval:

  • activate: launch application and/or bring to front
  • open: open a file
  • open location: open a URL
  • quit: quit the application

For example, this will work without requiring approval:

osascript <<EndOfScript
    tell application "Firefox"
        open location "https://scriptingosx.com"
    end
EndOfScript

Use non-AppleScript alternatives

Sometimes, similar effects to an AppleScript can be achieved through other means. This can be difficult to figure out and implement.

As an example, I used this AppleScript command frequently for setup before Mojave:

tell application "Finder" to set desktop picture to POSIX file "/Library/Desktop Pictures/BoringBlueDesktop.png"

While Mojave was in the beta and it wasn’t really clear if or how the PPPC exemptions could be managed, I looked for a different means. I discovered Cocoa functions to read and change the desktop picture without triggering PPPC, and built a small command line tool out of that: desktoppr.

The downside of this approach is that you know have to install and/or manage a command line tool on the clients where you want to use it. There are different strategies for this, but it is extra effort compared to “just” running an AppleScript.

Build PPPC profiles to pre-approve AppleEvents

Even after you have considered the above options to avoid sending AppleEvents to another process, there will still be several situations where it is necessary. For situations where a MacAdmin needs to run a script on several dozens, hundreds, or even thousands of Macs, user-approval is simply not a feasible option.

MacAdmins can pre-approve AppleEvents (and most other privacy areas) between certain processes with a Privacy Preferences Policy Control (PPPC) configuration profile. PPPC profiles can only be managed when pushed from a user-approved or automatically enrolled MDM.

You can build such a profile manually, but it is much easier to use a tool to build these:

Your MDM solution might have a specific tool or web interface for this, consult the documentation or ask you vendor.

There is one big requirement here, though: only applications and tools that are signed with a valid Apple Developer ID can be pre-approved this way, as the signature is used to identify and verify the binary.

Determining the process that needs approval

While you can sign shell scripts and other scripts this is often not necessary. As we have seen earlier, when we ran our script from Terminal, it wasn’t the script that requested approval but the Terminal application. When your scripts run from a management system or another tool, it may not be easy to determine which process exactly needs approval.

The most practical approach to determine this, is to log the output of the ’Transparency, Consent, and Control” system (tcc) and look which process is sending the requests.

First, either use a clean test system, or reset the approvals for the processes that you suspect may be involved with tccutil.

Then open a separate Terminal window and run this command which will show a stream of log entries from the tcc process:

> log stream --debug --predicate 'subsystem == "com.apple.TCC" AND eventMessage BEGINSWITH "AttributionChain"'

There will be a lot of noise in this output.

Then run the script in question, the way you are planning to run it during deployment. If you are planning to run the script from a management system, then do that right now. You will get a lot output in the stream above.

Even when you don’t have a good idea what the parent process is going to be, you can filter the output for osascript since this is usually the intermediary tool used.

In my example I found several entries similar to this:

   0    tccd: [com.apple.TCC:access] AttributionChain: RESP:{ID: com.barebones.bbedit, PID[1179], auid: 501, euid: 501, responsible path: '/Applications/BBEdit.app/Contents/MacOS/BBEdit', binary path: '/Applications/BBEdit.app/Contents/MacOS/BBEdit'}, ACC:{ID: com.apple.osascript, PID[18756], auid: 501, euid: 501, binary path: '/usr/bin/osascript'}, REQ:{ID: com.apple.appleeventsd, PID[577], auid: 55, euid: 55, binary path: '/System/Library/CoreServices/appleeventsd'}

The important information here is the responsible path which give me the binary and the enclosing application that tcc considers ‘responsible.’ This is the application you need to approve.

When you are running your scripts from a management system, your MDM vendor/provider should already have documentation for this, to save you all this hassle.

With all this information, you can build the PPPC profile with one of the above tools, upload it to your MDM and push it to the clients before the deployment scripts run.

Conclusion

While the added privacy around AppleEvents is welcome, it does add several hurdles to automated administration workflows.

There are some strategies you can use to avoid AppleScripts triggering the privacy controls. When these are not sufficient, you have to build a PPPC profile to pre-approve the parent process.

Weekly News Summary for Admins — 2020-09-25

If you thought that the week after the iOS 14 release would be a quiet week, you would have been wrong.

We got updates for the Keynote, Pages, Numbers, and iMovie, the first bug fix updates for iOS 14 and siblings, macOS Big Sur beta8 and, quite surprisingly: 10.15.7.

It makes you wonder why this update got the 10.15.7 and not “yet another Supplemental Update,” but this is a very welcome change. Many thanks to Mr Macintosh and Howard Oakley for covering the updates so well.

Virtual JNUC 2020 is next week! (September 29 through October 1). My session will be on “Scripting Jamf Pro: Best Practices” on Oct 1 at 11am CDT (18:00 Central European). There will be a live Q&A during and after the session. You can still register for free.

The MacSysAdmin Online will be later in October. Participation will be free, but you can support the team by buying the MacSysAdmin Online T-Shirt, which will also enroll you in an exclusive giveaway raffle.

And just in this week, the “EveryWorld” conference will be online from November 25 to 27. There is a call for participation.

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

News and Opinion

macOS 11 Big Sur

macOS Catalina 10.15 and iOS 14 Updates

MacAdmins on Twitter

  • Steve Hayman: “Well that’s easy.” (Read the thread for some Hayman scripting wisdom.)
  • Carl Ashley: “The elephant in the room: Keeping up to date with OS/app releases isn’t always important. Sometimes, being able to get s**t done with something that works is more important.” (Thread)
  • William Smith: “Next month, support for Microsoft Office for Mac changes in two ways: 1. With the release of Big Sur, only these N–2 versions are supported: macOS Big Sur macOS Catalina macOS Mojave 2. Office 2016 for Mac is end-of-lifed. Updates end. Support ends. KB docs begin retiring.”
  • mikey: “TIL there’s an osascript cache at ~/Library/Caches/com.apple.osascript/Cache.db
  • Carl Ashley: “Why is it, that in 2020, after many years of having MDM available, are we still not yet able to specify values to pass on to Setup Assistant, or even values for the settings that Setup Assistant sets that we can use in normal profile payloads?” (Thread)

Bugs and Security

Support and HowTos

Scripting and Automation

Apple Support

iWork 10.2 updates

Updates and Releases

To Listen

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!

Weekly News Summary for Admins — 2020-09-18

Update season has started. After the event on Tuesday, where Apple announced new Watches and iPads, iOS 14 shipped on Wednesday, giving developers and admins less than 24 hours advance warning and probably the shortest lived GM ever.

We also got macOS Big Sur beta 7 and new betas for iOS 14.2 and siblings.

The future releases of hardware and software this year should remain interesting. I expect at least two more events like this, one focussing on the new iPhones and the other for a new Apple Silicon Mac (or more). I would also guess that we will get the “missing” iOS 14.1 with the new iPhones, and 14.2 shortly after.

The reason this newsletter is a bit later than usual, is that I was finishing recording and editing my presentation for MacSysAdmin Online to submit it today, just in time for the deadline. This is the second presentation for a major MacAdmin conference that I recorded and finished this month. It feels strange that neither of these presentations will be streamed until October, but I am very much looking forward to when you get to see them and all the other presentations from both conferences.

Virtual JNUC 2020 is happening September 29 through October 1. My session will be on “Scripting Jamf Pro: Best Practices” on Oct 1 at 11am CDT (18:00 Central European). There will be a live Q&A during and after the session. You can still register for free.

The MacSysAdmin Online will be later in October. Participation will be free, but you can support the team by buying the MacSysAdmin Online T-Shirt, which will also enroll you in an exclusive giveaway raffle.

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

Apple Event: Time Flies

News and Opinion

macOS 11 Big Sur and iOS 14

MacAdmins on Twitter

  • Mr. Macintosh: “I’m hearing that the Jamf Pro 10.24 beta Big Sur fixes are in 10.24.1. Official support will be listed in the patch notes of 10.25 (not sure on 10.25 version numbering). 10.24.1 = Big Sur compatible. 10.25 = Big Sur official supported version.”
  • Andreas Schenk: “Using an iPad as an additional screen for macOS with sidecar seems to still deliver notifications from iPadOS, even if macOS is in DND mode. So if you happen to run a presentation using sidecar, first set the iPad to do not disturb, then use sidecar.”

Bugs and Security

Support and HowTos

Scripting and Automation

Apple Support

Updates and Releases

To Listen

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!

Weekly News Summary for Admins — 2020-09-11

Apple has announced an event next week September 15, 10am PDT. They have seeded many people in the press and on social media with the information that there will be no iPhones at this event. Expectations are for a new watch and iPad Air.

A new watch will likely require watchOS 7, which will require iOS 14, so the Apple systems upgrade season will start soon after this event. If previous years can be used to extrapolate (not at all certain this year) the iOS system upgrades could be available Friday, September 18 or September 25.

I am not concerned at all about no iPhones or Macs at this event. These will probably be remote, pre-recorded events like they did at WWDC. Apple can easily do multiple of these events until well into October, giving every product full attention.

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

Headlines

News and Opinion

macOS 11 Big Sur and iOS 14

macOS Catalina 10.15 and iOS 13 Updates

MacAdmins on Twitter

  • Arek Dreyer: “On your Mac, you can Option-Click the Notification Center icon to toggle Do Not Disturb.”
  • Arek Dreyer: “A bunch of Apple Reference and User Guide pages now have a ”Search the user guide” field, nice!”
  • Nathaniel Strauss: “Still true in Big Sur beta 6. Apple privacy/security team won a stupid fight… and everyone else lost. PPPC is needlessly confusing for most people. Schools won’t use Big Sur for at least 4–6 months after release. What a mess.” (More info from Michael Tsai)
  • Corey Quinn: “Myth: Companies are accelerating their cloud migrations due to COVID19. Fact: Companies are suddenly making better decisions since their executives aren’t being exposed to enterprise software ads in airports.”

Bugs and Security

Support and HowTos

Scripting and Automation

Apple Support

Updates and Releases

To Listen

Just for Fun

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!

macOS Version Big Sur Update

Versioning software is a surprisingly difficult task. The version number conveys technical information: how much change can you expect and might it break existing workflows and data? Users will be more willing to pay for a major upgrade with new features, so the version number is used as a marketing tool. But for developers and MacAdmins, the version number has to be as granular as possible, ideally with a different number for each build made.

Because of these, sometimes opposing, interests, it is no wonder that versioning is often a problem for MacAdmins.

A brief history of the Mac operating system versions

Before the “Mac OS” label, the Macintosh operating system was called “System 7.” “Mac OS 8”, code-named “Copland,” was supposed to be the new operating system with all the new features, but the project kept slipping and then was cancelled. The “System 7.7” update was then re-named “Mac OS 8” to get Apple out of some third party licensing deals, which were set to expire on version 8. Marketing and legal matters decided the versioning here. (But it wasn’t all just marketing: Mac OS 8 also got the new interface design that had been created for Copland.)

When Apple announced the NextSTEP based major overhaul for the Macintosh in the late nineties, they chose to not give it a different name and new version numbers. Instead they chose to label the new system as “Mac OS X”, where the “X” was read as the roman numeral ten. I assume this was a marketing choice to demonstrate continuity with the previous versions, which had been “Mac OS 8” and “Mac OS 9.”

The first version of Mac OS X had the numerical version number 10.0.0 and got four “updates” to 10.0.4 Then it got the first major “upgrade” to 10.1. This broke with conventional versioning as major upgrades should get a new major number. When “Mac OS X 10.2 Jaguar” was announced at WWDC in 2002, it was obvious that Apple now considered “Mac OS X” a brand and would stick to the 10 in the system version numbers.

With the “Xserve,” the ‘X’ became a moniker to represent Apple’s “professional” or “EXpert” hardware and distinguish them from the ‘i’ prefix used for the consumer friendly devices and software. (iMac, iBook, iPod, iTunes, iMovie, iPhoto, etc.) Later “pro” software tools, such as “Xcode,” “Xsan,” and “Xgrid” picked up that prefix. Confusingly, the leading “X” was pronounced ‘ecks’ and the trailing ‘X’ in “Mac OS X” was still pronounced as ‘ten.’ Or at least that was what Apple marketing insisted it should be called.

In 2012, Apple dropped the “Mac” from the operating system for “OS X Mountain Lion” (10.8) The “X” represented the “pro” nature of Mac platform, as opposed to “iOS” for iPhone and iPad. Apparently, the “X” was considered a stronger brand for “pro” than “Mac” at the time…

This changed when Apple finally dropped the “X-as-ten” and returned the “Mac” with “macOS Sierra” (10.12) in 2016.

Even without the “X” in the system name, the ‘10’ has remained in the version number up to macOS 10.15 Catalina.

(The “X-as-ten” lives on with “Final Cut Pro X” and “Logic Pro X”. The prefix “X” lives on with “Xcode.”)

Big Sur goes to 11

The naming and versioning of the Mac platforms operating system was largely driven by symbolism, marketing and even legal matters. The same is true this year: Apple has finally given up on the “ten” and will raise the major version of macOS to 11.

I have a post on my opinion and reaction to macOS 11. Whatever the reasons, this is the year that we will get macOS 11.

When you go to “About this Mac” on a Mac running the Big Sur beta, it will proudly announce that it is running macOS 11.0. You get the same result when you run sw_vers:

% sw_vers -productVersion
11.0

This seems easy enough, however, there is a catch to this.

10.16 vs 11.0

Big Sur will not always report 11.0 as the macOS version. It might report 10.16 in some cases. These cases are meant for situations where software might just check the second part of the version for version checks.

The rules are detailed in this post from Howard Oakley.

In Big Sur you can force the compatibility mode by setting the SYSTEM_VERSION_COMPAT environment variable to 1:

export SYSTEM_VERSION_COMPAT=1
> sw_vers -productVersion
10.16

Checking the Version

When you have a script that checked the version of macOS (or Mac OS X or OS X), so far it was safe to ignore the first number of the product version and only compare the second. For example to see if macOS was Mojave or newer, you probably would have done something like this:

minorVersion=$(sw_vers -productVersion | awk -F. '{ print $2; }')
if [[ $minorVersion -ge 14 ]]; then
  echo "Mojave or higher"
fi

Now, with the release of macOS 11.0, this setup will return 0 for the minorVersion and fail.

The obvious solution here would be to extract the majorVersion as well and compare that first:

majorVersion=$(sw_vers -productVersion | awk -F. '{ print $1; }')
minorVersion=$(sw_vers -productVersion | awk -F. '{ print $2; }')
if [[ $majorVersion -ge 11 || $minorVersion -ge 14 ]]; then
  echo "Mojave or higher"
fi

This will work well enough, even when the script runs in a setup where it might get 10.16 as the version number. But is not particularly nice to read. Also, when you want to compare update versions, these will be (presumably) the minorVersion for Big Sur and later and the third part of the version number in Catalina and earlier and things will get even more messy quickly.

Maybe there is a better way of doing this than using the product (marketing) version of macOS?

Build Version

As I mentioned earlier, the user visible version may not be granular enough for the needs of developers. And because of this macOS has a second version, called the “build version”

The build version for the current version of macOS Catalina as I am writing this is 19G2021.

> sw_vers -buildVersion
19G2021

You can also see the build version in the “About this Mac” window when you click on the version number.

The build version consists of three parts and a fourth optional one. The first number is the Darwin Version. The following capital letter designates the update. The following number (up to four digits) is the specific build number. Sometimes the build number is followed by a lower case letter.

Darwin Version

This part of the version takes its name from the Darwin core of macOS.

The Darwin Version is number that is increased on every major release of macOS. Mac OS X 10.2 Jaguar was the first release of Mac OS X to consistently report its Darwin Version as 6. From that you can conclude that 10.0 had Darwin version 4 which makes sense, because it was the fourth release of NextSTEP, the operating system Mac OS X is based on.

macOS 10.15 Catalina, has a Darwin version of 19 and Big Sur reports 20.

You can also get the Darwin version in the shell from the OSTYPE environment variable:

> echo $OSTYPE
darwin19.0

But keep in mind that environment variable may not be set depending on the context your script runs in.

A safer way to get the Darwin version is with the uname command:

> uname -r
19.6.0

This Darwin version includes the update information.

Updates

In the build version updates are tracked with a capital letter. The letter A stands for the .0 or first release of a major version. B signifies the second release or first update or .1 release, and so on.

The current Catalina build version starts with 19G so we know it is the seventh release or sixth update to Catalina (10.15.6). The current Big Sur beta starts with 20A so it is the first release or .0 version.

Build numbers

The significance of the build number is most often seen during the beta phase. While the Darwin version and update letter are fixed during the beta phase, the build number increases with every beta release. This is the most granular number we have to determine the version.

For each update and major release the build number starts over, so it can only be used to compare releases for the same major release and update version.

Traditionally, there was a difference between two- and three-digit build numbers and four-digit build numbers. The builds with lower numbers of digits were general release builds, that will run on all Macs that support this version of macOS. The four digit build numbers designated either a security update or a hardware specific build.

Hardware specific builds occur when a new Mac model is released. These usually get a hardware specific build of macOS, since the drivers necessary for the new hardware are not included in the current general release version. Even though the product version numbers of macOS are the same for the general release and the hardware specific release, they have different build numbers.

Usually, the hardware specific drivers are merged into the general release on the next update. However, until the builds are merged, MacAdmins may have to manage hardware specific system installers and workflows for new hardware. This was especially annoying with the release of the 2018 MacBook Pro which had a specific build of 10.13.6 that was never merged into the general 10.13 build. MacAdmins that wanted or needed to support 10.13 had to manage a separate installer for these MacBooks.

Intruigingly, the Big Sur beta is different: its build number started in the 4000s and switched to the 5000s with beta 3.

Special builds

Some releases of macOS have a trailing lower case letter after the build number. This is particularly common during the beta phase. It is unclear what this letter designates exactly. It might designate that the installer application was re-built one or more times.

You can use regular expressions to parse out all the individual pieces of the build version:

if [[ $buildVersion =~ ([[:digit:]]{1,2})([[:upper:]])([[:digit:]]+)(.*) ]]; then
    darwinVersion=$match[1]
    updateLetter=$match[2]
    buildNumber=$match[3]
    specialBuild=$match[4]
else
    echo "couldn't parse build version"
    exit 2
fi

But in most cases, you will not need this level of detail.

Using the Build Version

The build version provides a way to compare macOS system versions that is not subject to the whims of marketing. We can even use it distinguish hardware specific builds of macOS from general versions or determine if security or supplemental updates have been applied.

For most comparisons, we only need the Darwin version and maybe the update.

The Darwin version has had two digits since Mac OS X 10.6 Snow Leopard. It is safe to assume that you won’t be managing Macs running 10.5 Leopard any more. (And if you do, they will probably be “hand-fed” and not subject to your deployment and update automations.) Assuming a two digit Darwin version, we can use string comparison to compare build versions:

# check if Mojave or higher
if [[ $(sw_vers -buildVersion) > "18" ]]; then
...

Since all versions of Mojave start with 18A... they are all alphabetically greater than 18. The same would go if you want to check for a maximum macOS version:

# check if Mojave or earlier
if [ $(sw_vers -buildVersion) < "19" ]; then
...

You can also filter for specific minimum updates:

# check if Mojave 10.14.6 or later
if [ $(sw_vers -buildVersion) > "18E” ]; then
...

By using the build version, we are avoiding all the trouble that the “marketing-driven” build version brings with it.

zsh solution

The above works for sh, bash and zsh scripts. However, when you are using zsh, there is another useful solution. zsh provides a function to compare versions called is-at-least.

When you use zsh in the Terminal interactively, it is probably already loaded, but when you want to use it in scripts, you should use autoload to make sure it is loaded. Then you can use is-at-least this way:

autoload is-at-least
# check for Mojave or higher
if is-at-least 10.14 $(sw_vers -productVersion); then
...

Since both 11.0 and 10.16 are higher than 10.14 this will work no matter what number Big Sur might be reporting, but if you want to check that the system is Big Sur, you want to use 10.16 as the minimum, which covers both possible values:

autoload is-at-least
# check for Big Sur or higher
if is-at-least 10.16 $(sw_vers -productVersion); then
...

Conclusion

The change of the version number in macOS 11 Big Sur might affect or even break some of your system version checking in your deployment and management scripts. There are some nice and easy solutions that are more resilient to changes in the “marketing” product version.

Weekly News Summary for Admins — 2020-09-04

How can it be September already!? Where did the summer go?

Apple’s beta phase is heating up with a new beta release for iOS and macOS. We also got iOS and iPadOS 13.7.

Since Fall is here, so are some more virtual conferences. I will have sessions prepared for Virtual JNUC and MacSysAdmin Online.

Virtual JNUC 2020 is happening September 29 through October 1. You can still register for free.

The MacSysAdmin Online will be later in October. Participation will be free, but you can support the team by buying the MacSysAdmin Online T-Shirt, which will also enroll you in an exclusive giveaway raffle.

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

macOS 11 Big Sur and iOS 14

macOS Catalina 10.15 and iOS 13 Updates

Bugs and Security

Support and HowTos

Scripting and Automation

Apple Support

To Listen

Just for Fun

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!

Weekly News Summary for Admins — 2020-08-28

Some great posts from fellow MacAdmins this week. New betas for iOS 14 and iOS 13.7(!) dropped, but none for macOS so far.

Remember that you can still register for Virtual JNUC 2020 for free. you won’t just get to see my great talk, but there are many other amazing talks from amazing MacAdmins.

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

News and Opinion

macOS 11 Big Sur and iOS 14

MacAdmins on Twitter

  • William Smith: “Outlook for Mac 16.38 can let users try New Outlook. MacAdmins can manage this preference: Domain: com.microsoft.Outlook Key: EnableNewOutlook Values (integer): 0 = Switch hidden (default) 1 = Switch displayed, off 2 = Switch displayed, on 3 = Enabled, switch hidden”
  • mikeymikey: “If you’re not a full Screen aficionado – you may have seen that hovering over the zoom control gives you options you don’t care for – but did you know those options change to non-full screen windowed choices if you hold down Option?”
  • tlark: “The thing that kills me the most about TCC/PPPC is there is no real clear documentation on how to properly implement it. You stream logs, run things and play a game of whack-a-mole. I am all about increased security posture, but come on Apple, help us configure it.”

Bugs and Security

Support and HowTos

Scripting and Automation

Updates and Releases

To Listen

Just for Fun

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!

Running a Command as another User

This post is an update to an older post on the same topic. macOS has changed and I had a few things to add. Rather than keep modifying the older post, I decided to make this new one.

As MacAdmins, most of the scripts we write will use tools that require administrator or super user/root privileges. The good news here that many of the management tools we can use to run scripts on clients already run with root privileges. The pre– and postinstall scripts in installation packages (pkgs), the agent for your management system, and scripts executed as LaunchDaemons all run with root privileges.

However, some commands need to be run not as root, but as the user.

For example, the defaults command can be used to read or set a specific setting for a user. When your script, executed by your management system, is running as root and contains this command:

defaults write com.apple.dock orientation left

Then it will write this preference into root’s home directory in /var/root/Library/Preferences/com.apple.dock.plist. This is probably not what you intended to do.

Get the Current User

To get the correct behavior, you need to run the command as a user. Then the problem is as which user you want to run as. In many cases the answer is the user that is currently logged in.

I have written a few posts about how to determine the currently logged in user from shell scripts and will use the solution from those:

currentUser=$( echo "show State:/Users/ConsoleUser" | scutil | awk '/Name :/ { print $3 }' )

This will return the currently logged in user or loginwindow when there is none. This is the Posix sh compatible syntax, which will also run with bash or zsh.

Running as User

There are two ways to run a command as the current user. The first is with sudo:

sudo -u "$currentUser" defaults write com.apple.dock orientation left

The second is with launchctl asuser.

uid=$(id -u "$currentUser")
launchctl asuser $uid launchctl load com.example.agent

The launchctl command uses the numerical user ID instead of the user’s shortname so we need generate that first.

It used to be that the sudo solution would not work in all contexts, but the launchctl asuser solution would. This changed at some point during the Mojave release time.

Now, the lauchctl asuser works and is required when you want to load and unload LaunchAgents (which run as the user), but it does not seem to work in other contexts any more.

So, for most use cases, you want to use the sudo solution but in some you need the launchctl form. The good news here is, that you can play it safe and use both at the same time:

launchctl asuser "$uid" sudo -u "$currentUser" command arguments

This works for all commands in all contexts. This is, however, a lot to type and memorize. I built a small shell function that I use in many of my scripts. Paste this at the beginning of your scripts:

# convenience function to run a command as the current user
# usage:
#   runAsUser command arguments...
runAsUser() {  
  if [ "$currentUser" != "loginwindow" ]; then
    launchctl asuser "$uid" sudo -u "$currentUser" "$@"
  else
    echo "no user logged in"
    # uncomment the exit command
    # to make the function exit with an error when no user is logged in
    # exit 1
  fi
}

and then you can use the function like this:

runAsUser defaults write com.apple.dock orientation left

runAsUser launchctl load com.example.agent

Note: the function, as written above, will simply do nothing when the Mac is sitting at the login window with no user logged in. You can uncomment the exit 1 line to make the script exit with an error in that case. In your script, you should generally check whether a user is logged in and handle that situation before you use the runAsUser function. For example you could use:

if [ -z "$currentUser" -o "$currentUser" = "loginwindow" ]; then
  echo "no user logged in, cannot proceed"
  exit 1
fi

Insert this at the beginning of your code (but after the declaration of the currentUser variable) and you can assume that a user is logged in and safely use the $currentUser variable and the runAsUser function afterwards. The exact detail on when and how you should check for a logged in user depends on the workflow of your script. In general, earlier is better.

When to Run as User

Generally, you should run as the user when the command interacts with the user interface, user processes and applications, or user data. As MacAdmins these are common commands you should run as the user;

  • defaults, when reading or changing a user’s preferences
  • osascript
  • open
  • launchctl load|unload for Launch Agents (not Launch Daemons)

This is not a complete list. Third party configuration scripts may need to be run as root or user. You will need to refer to documentation or, in many cases, just determine the correct action by trial and error.

Sample Script

I have put together a script that combines the above code into a working example.

Weekly News Summary for Admins — 2020-08-21

Welcome back! I get the impression I was the only one to take a while off this summer. So many post to sort through and link to…

I will be presenting at Virtual JNUC2020 this year. My session is “Scripting Jamf: Best Practices” (JNUC307) and is scheduled for Oct 1 at 11am CT (18:00 Central European time). The entire session schedule can be reviewed on their site and you can still register for free!

I am also preparing something for the MacSysAdmin Online. This will be a free online event this year where they will publish some of the best presentations from previous years and new content as well. You can support the team by buying the MacSysAdmin Online T-Shirt, which will also enroll you in an exclusive giveaway raffle.

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

News and Opinion

macOS 11 Big Sur and iOS 14

macOS Catalina 10.15 and iOS 13 Updates

MacAdmins on Twitter

  • William Smith: “Small undocumented change with Policies in Jamf Pro 10.22 that I didn’t learn about until today: New policies no longer automatically include the Restart payload.”
  • Victor (groob): “Instead of asking ”experts“ for how you’d go about doing something, tell them what you tried, and ask why it’s not working.”
  • Anthony Reimer: “Intriguing. On the new 27-inch iMac, you can not customize the 256 GB of storage on the base model. You must move up to the middle model to get 512GB or more of storage.”
  • Victor (groob): “Four betas. Four subtle ways Apple broke a core workflow in MDM zero touch provisioning. All undocumented.”
  • Graham Pugh: “Jamf Self Service policies will not run on macOS 10.12 Sierra on Jamf Pro versions 10.22 and above. Jamf will not fix this as they drop support for Sierra in the next release.”
  • Anthony Reimer: “I’ve updated my Mac Obsolescence chart with the new iMac (hopefully making an appearance in a home near me). obsolescence.jazzace.ca
  • Per Olofsson: “Companion niche tip: creating a sparsebundle from a folder and then converting it to a compressed read only dmg is multithreaded and faster than creating the dmg directly. In my testing the resulting dmg will also be smaller.”
  • Neil Martin: “TIL in profilecreator if you long-click the export button, you can export your payloads as MCX-style plists – handy!”
  • Erik Schwiebert: “Two month alert! Microsoft support for Office 2016 for the Mac ends on October 13, 2020

Bugs and Security

Support and HowTos

Scripting and Automation

Updates and Releases

To Watch

To Listen

Just for Fun

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!

Weekly News Summary for Admins — 2020-07-24

You can’t really tell it from the weather here in the Netherlands, but summer is here!

Summer brings more beta testing: the third beta of the new Apple systems dropped this week. It also brings vacation. This newsletter will be on vacation until late August. As usual, I will keep gathering interesting posts and links and return with a big August summary.

Hope you get to enjoy your summer and vacation. Stay safe!

If you would rather get the weekly newsletter by email, you can subscribe to the Scripting OS X Weekly Newsletter here!! (Same content, delivered to your Inbox once a week.)

News and Opinion

macOS 11 Big Sur and iOS 14

Coronavirus and Remote Work

MacAdmins on Twitter

  • Rich Trouton: “I’ve bought a share of Jamf stock. Now I can show up at both JNUC and shareholder meetings with my gripes.”

Bugs and Security

Support and HowTos

Scripting and Automation

Updates and Releases

To Watch

To Listen

Support

If you are enjoying what you are reading here, please spread the word and recommend it to another Mac Admin!

If you want to support me and this website even further, then consider buying one (or all) of my books. It’s like a subscription fee, but you also get a useful book or two extra!