Weekly News Summary for Admins — 2021-04-16

This week Apple finally sent out the invitations for an event next week. The “Spring Loaded” event will take place next week, April 20, at 10am PDT.

Release of iOS 14.5, macOS 11.3, and siblings are likely on or around that day then. We did get an eighth beta this week. Next week should be interesting.


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macOS Terminal and Shell Book Cover

macOS Terminal and Shell:
You have always wanted to ‘learn Terminal,‘ right? This book teaches how (and why) to use the command line on macOS. Get it on Apple Books!

(If you have already bought the book, please leave a review on the Apple Books Store. Thank you!)


In other news, Parallels and Docker now have officially released Apple silicon native solutions. Ironically, Parallels cannot (yet?) host macOS Big Sur guest systems, only Windows 10 for ARM (preview) and ARM Linux systems.

The Docker does not come as a Universal download, but as two seperate downloads, which seems a common thing in this transition. Why is it that so many apps are separate downloads in this transition?

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Scripting OS X — Weekly News Summary for Admins — 2021-04-09

Another week and no update from Apple. We did get another round of betas (beta7, 20E5229a) for macOS, iOS and siblings.

But we did get an announcement of Apple Tiles… no, wait… third party support for “Find My…” tracking. Apple’s plan to keep releasing something every week continues.


To support this weekly news summary, please consider:

macOS Terminal and Shell Book Cover

macOS Terminal and Shell:
You have always wanted to ‘learn Terminal,‘ right? This book teaches how (and why) to use the command line on macOS. Get it on Apple Books!

(If you have already bought the book, please leave a review on the Apple Books Store. Thank you!)


📰News and Opinion

🐦MacAdmins on Twitter

  • Tim Perfitt: “MDS 4 is coming along. The current build adds a fancy new button.” (Thread)
  • Joel Rennich: “It’s Wednesday… so that means more fun with Single Sign On Extensions! This time we’re doing a bit of an “off-label” use of the SSOE and making it authoritative for a ZTNA service instead of an IdP which lets Xcode use modern auth directly for repos.” (Thread)
  • Kelsey Hightower: “Software isn’t enterprise ready until it has a “contact sales” pricing tier.”

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🤖Scripting and Automation

🍏Apple Support

♻️Updates and Releases

📺To Watch

🎧To Listen

🎈Just for Fun

  • James Thomson: “This isn’t necessarily pretty, but it does work! You can roll dice from an AppleScript, check if they are still rolling, and get the final result. All in a UIKit-based Catalyst app.”

📚 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 as well!

Get Password from Keychain in Shell Scripts

MacAdmin scripts often require passwords, mostly for interactions with APIs.

It is easiest to store the password in clear text, but that is obviously a terrible solution from a security perspective. You can pass the password as an argument to your script, but that is inconvenient and may still appear in clear text in the ps output or the shell history.

You can obfuscate the password with base64, but that is easily reversible. You can even try to encrypt the password, but since the script needs to be able to decrypt the password, you are just adding a layer of complexity to the problem.

macOS has a keychain, where the user can store passwords and allow applications and processes to retrieve them. We can have our script retrieve a password from a local keychain.

There are limitations to this approach:

  • the password item has to be created in the keychain
  • the user has to approve access to the password at least once
  • the keychain has to be unlocked when item is created and when the script runs—this usually requires the user to be logged in
  • the user and other scripts can find and read the password in the Keychain Access application or with the security tool

Because of these limitations, this approach is not useful for scripts that run without any user interaction, e.g. from a management system. Since the user can go and inspect the key in the Keychain Access is also not well suited for critical passwords and keys.

However, it is quite useful for workflow scripts that you run interactively on your Mac. This approach has the added benefit, that you do not have to remember to remove or anonymize any keys or passwords when you upload a script to GitHub or a similar service.

Note: Mischa used this in his ‘OnAirScanner’ script.

Update: I didn’t remember this, but Graham Pugh has written about this before.

How to Store a Password in the Keychain

Since adding the password to your keychain is a one-time task, you can create the password manually.

Open the Keychain Access application and choose “New Password Item…” from the Menu. Then enter the Keychain Item Name, Account Name and the password into the fields. The “Keychain Item Name” is what we are going to use later to retrieve the password, so watch that you are typing everything correctly.

You can also add the password from the command line with the security command.

> security add-generic-password -s 'CLI Test'  -a 'armin' -w 'password123' 

This will create an item in the Keychain with the name CLI Test and the account name armin and the horribly poor password password123.

How to Retrieve the Password in the Script

To retrieve a password from the keychain in a script, use the security command.

> security find-generic-password -w -s 'CLI Test' -a 'armin'

This will search for an item in the keychain with a name of CLI Test and an account name of armin. When it finds an item that matches the name and account it will print the password.

The first time you run this command, the system will prompt to allow access to this password. Enter your keychain password and click the ‘Always Allow’ button to approve the access.

This will grant the /usr/bin/security binary access to this password. You can see this in the Keychain Access application in the ‘Access Control’ tab for the item.

When you create the item with the security add-generic-password binary, you can add the -T /usr/bin/security option to immediately grant the security binary access.

Whether you grant access through the UI or with the command, keep in mind that a every other script that uses the security binary will also gain access to this password.

For very sensitive passwords, you can just click ‘Allow’ rather than ‘Always Allow.’ Then the script will prompt interactively for access every time. This is more secure, but also requires more user interaction.

Once you have tested that you can retrieve the password in the interactive shell, and you have granted access to the security binary, you can use command substitution in the script to get the password:

cli_password=$(security find-generic-password -w -s 'CLI Test' -a 'armin')

This command might fail for different reasons. The keychain could be locked, or the password cannot be found. (Because it was either changed, deleted or hasn’t been created yet.) You want to catch that error and exit the script when that happens:

pw_name="CLI Test"
pw_account="armin"

if ! cli_password=$(security find-generic-password -w -s "$pw_name" -a "$pw_account"); then
  echo "could not get password, error $?"
  exit 1
fi

echo "the password is $cli_password"

Scripting OS X — Weekly News Summary for Admins — 2021-04-02

Anther week, another beta release. Apple has released the sixth beta for macOS 11.3 (20E5224a), iOS 14.5, and siblings.

Apple has also announced the dates for WWDC 2021. It will take place June 7–11 “to a screen near you.” I have updated the conference overview on Scripting OS X. So, we have two months left before we enter the next major beta cycle. But, did we ever leave the Big Sur beta cycle?


To support the weekly news summary, please consider:

macOS Terminal and Shell Book Cover

macOS Terminal and Shell:
You have always wanted to ‘learn Terminal,‘ right? This book teaches how (and why) to use the command line on macOS. Get it on Apple Books!


📰News and Opinion

🐦MacAdmins on Twitter

  • Nathaniel Strauss: “We’re 4 months into Big Sur. If your product still doesn’t have support you’ve missed 1/3 of the OS cycle. You’re not behind, you’re slipping into irrelevant.”
  • Edward Marczak: “Big thanks to everyone in the #macadmin community releasing open source solutions. So much thought and care goes into this work that’s not only needed to fill gaps, but also every bit as good as commercial products. Thank you also for sharing documentation and good example code.”
  • James Turner: “Running a mixed fleet I am confident saying that the value in the community and open source solutions available for #macadmin is immeasurable.”
  • Nathaniel Strauss: “First time a DMG has advertised at me. @ReflectorApp Hey, consider not doing this. There are admins out there using your Sparkle feed for automation. Pretty sure that’s not a valid version string.” (Image)

🔐Security and Privacy

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♻️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 — 2021-03-26

No major Apple announcement either this week. We got the fifth beta for macOS 11.3, iOS 14.5 and siblings. Apple also released new versions for the apps formerly known as iWork. Is this the start of the spring release season?

Talking about spring releases, Mac OS X was released twenty years ago this week!


To support the weekly news summary, please consider:

macOS Terminal and Shell Book Cover

macOS Terminal and Shell:
You have always wanted to ‘learn Terminal,‘ right? This book teaches how (and why) to use the command line on macOS. Get it on Apple Books!


List of upcoming conferences, dates, and their video archives on my website:

📰News and Opinion

🌅macOS 11 Big Sur and Apple silicon Macs

🔨Support and HowTos

🤖Scripting and Automation

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♻️Updates and Releases

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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!

Twenty Years of Mac OS X

Mac OS X 10.0 was released March 24, 2001. Twenty years ago today.

The PowerBook, iMac, iPod, iPhone, iPad, and Apple Watch are obviously big steps along the way from Apple as a ‘beleagured,’ minor computer maker with an uncertain future to the $2 trillion tera-corp they are today. It is easy to focus on the hardware. But Mac OS X was at least as important.

Back then, it was essential that Apple move forward from ‘classic’ Mac OS. Protected memory, multi-user setups, and support for multiple applications running safely side-by-side were the main advantages of Mac OS X over Mac OS 9. But Mac OS X also brought with it the Unix core (and shell), a new display technology, and the Cocoa frameworks.

The transition was rough for the existing Mac users. The early versions were not as complete and stable as one would have hoped. The processing requirements of early Mac OS X pushed existing Mac hardware to their limits. Many application vendors dragged their feet adopting Mac OS X and the new technologies and features available.

But Mac OS X made the Mac interesting for a whole new group of people. It was the only platform at then time that they had Microsoft and Adobe productivity app as well as the Unix shell and tools available. This was a huge bonus for web designers and developers, but also for scientists.

Apple built some of the best laptops of the time. It might seem strange now, but having a portable, battery-powered Unix workstation, which also ran Word, Excel, Photoshop, and could edit videos, was un-imaginable just a few years before.

Then, Apple stripped down Mac OS X, so it could run on on a phone. Up until then, portable devices had very basic and minimal operating systems. They were also locked down and installing additional software was complicated and often expensive.

The early versions of iPhone OS were also basic and minimal compared to Mac OS X, but they held the promise of extension and growth. The iPhone had potential and Apple delivered on that promise with every system update. They treated the iPhone as a computer, rather than a gadget. It took a few years, but with the iPhone, people went from having one computer, to two computers: one in your pocket and one on your desk or in your bag.

Today, Apple has a range of operating systems from the watch on your wrist to the large screen in your living room, all going back to Mac OS X 10.0 twenty years ago. macOS is just one element in this ecology of devices. We don’t just have one computer, we have many. A spectrum of computers, most of them wireless and battery-powered, each with different strengths. These computers might all be from Apple, or from a variety of vendors.

macOS is part of this spectrum. In the past years, Apple has changed the name and just last year the major version number of their operating system for laptops and desktops.

Sometimes it seems that Apple has lost sight of what makes Macs an important tool. With Apple silicon for Macs, it seems that Apple is re-focusing on the Mac and seeing how they can improve macOS, while also improving the eco-system as a whole.

“macOS 11” holds a promise for continued and even re-newed growth. Like the first “Mac OS X” twenty years ago, and the first iPhone OS, there is potential.

I am looking forward to the next twenty years!

Script Identity Crisis – get the Path to the Current Script

In shell scripting, there are many situations where you want to know the path to the script file itself.

I use this frequently in scripts that build pkgs, because I want the script to access or create files relative to the script or its enclosing folder. In other words: the script sits in some project folder, and you want to get the path to that project folder.

Some scripts just use the current working directory, but since you can launch scripts from outside the current working directory, this is quite unreliable.

One example is this script from my book ‘Packaging for Apple Administrators‘ which builds an installer package for a desktop picture from resources in the same folder.

In that package build script I have the following line:

projectfolder=$(dirname "$0")

This is a useful but somewhat tricky line. It will work in most situations, but not all. To understand when it might fail, we will have to unravel it from the inside.

The $0 variable is the first element of the command line as it is entered in to the prompt and contains the command itself. In our case it will most likely be ./buildBoringDesktopPkg.sh.

The dirname command removes the last element from a path. This will return the path to the directory containing the item you give it. When we do dirname $0 after launching the script with ./buildBoringDesktopPkg.sh we will get . which is the current working directory, but also the parent directory of the script.

When you launch the build script with a different working directory, i.e. like

> Projects/BoringDesktop/buildBoringDesktopPkg.sh

The $0 argument will be Projects/BoringDesktop/buildBoringDesktopPkg.sh the dirname will return Projects/BoringDesktop/. This is all good and it will still find the resources and create the pkg file in its project folder.

In most situations the syntax used to call your script will be a relative or absolute path to the script. Something like ./buildPkg.sh or ~/Projects/Tools/my_script.sh. When the shell ‘sees’ a slash / in the command, it will assume this is the path to the script or executable and use that.

But when there is no slash / in the command, the shell will use the directories listed in the PATH environment variable to look for the command. This is the reason you can type sw_vers instead of having to write /usr/bin/sw_vers.

This is also the reason you have to type ./my_script.sh to run a script you are working on. Your script is not in the PATH, but the command contains a slash and tells the shell exactly where to look (in the current directory). When you just type my_script.sh the shell will look in the PATH directories, not find your script, and error out. (Unless your current directory happens to be in the PATH.)

Note: Learn the details about PATH in my new book: “macOS Terminal and Shell

So, there are a lot of pieces that are really confusing here. Let’s create a script that will help us visualize this:

#!/bin/sh

echo "pwd: $(pwd)"
echo "\$0: $0"
echo "dirname \$0: $(dirname $0)"

This script shows the values of the current working directory, the $0 argument, and the value returned by dirname $0. Save this script as script_path_test.sh in your Desktop folder.

> cd Desktop                      
> ./script_path_test.sh     
pwd: /Users/armin/Desktop
$0: ./script_path_test.sh
dirname $0: .
> cd ~                  
> Desktop/script_path_test.sh     
pwd: /Users/armin
$0: Desktop/script_path_test.sh
dirname $0: Desktop

So far, so good. While some of these paths look a little odd, they all return the expected values.

But now imagine we like our script so much, that we use it a lot. To save on typing the path to the script all the time, we add a symbolic link to it to /usr/local/bin. This puts our script in the default PATH (for an interactive shell) and we can now execute it without needing to type the path to it:

> sudo ln -s ~/Desktop/script_path_test.sh /usr/local/bin/script_path_test.sh
> script_path_test.sh
pwd: /Users/armin
$0: /usr/local/bin/script_path_test.sh
dirname $0: /usr/local/bin

So, this is less ideal. When you enter just script_path_test.sh the shell finds the symbolic link in /usr/local/bin and runs it. The $0 argument points to the symbolic link instead of the actual script and hence dirname $0 points to /usr/local/bin which is not where the resources for our script are.

(Remember to delete this symbolic link from /usr/local/bin/ when you are done with this.)

We need a tool that resolves symbolic links.

There are quite a few solutions to this, many of which can be found in this Stack Overflow post.

GNU-based systems have a realpath command line tool, which does exactly this. macOS does not have this tool. You can add GNU tools to macOS with many of the popular package managers, but that introduces a dependency and seems overkill.

Python has a function that does this. Add this line to the script:

echo "python realpath: $(python -c "import os; print(os.path.realpath('$0'))")"

This works fine, however, the built-in Python for macOS is deprecated. We don’t want to introduce this dependency, when it might go away in a future macOS update.

Then I found this post where I learned that zsh has a parameter expansion modifier to return the absolute path while resolving symbolic links.

Let’s modify our script to use zsh:

#!/bin/zsh

echo "pwd: $(pwd)"
echo "\$0: $0"
echo "dirname \$0: $(dirname $0)"

echo "\${0:A}: ${0:A}"
echo "dirname \${0:A}: $(dirname ${0:A})"

and then we can run our script:

> script_path_test.sh
pwd: /Users/armin
$0: /usr/local/bin/script_path_test.sh
dirname $0: /usr/local/bin
${0:A}: /Users/armin/Desktop/script_path_test.sh
dirname ${0:A}: /Users/armin/Desktop

Zsh to the rescue. We have a solution! Zsh is pre-installed on every macOS and since Apple chose it as their default shell since Catalina, it will be around for a while longer.

But what if you have sh or bash scripts that you cannot just quickly convert to zsh? The good news here is that we can create a zsh one-liner that does this, even from a bash or sh script, very similar to the python one-liner above.

echo "zsh absolute path: $(zsh -c 'echo ${0:A}' "$0")"
echo "zsh dirname absolute: $(dirname $(zsh -c 'echo ${0:A}' "$0"))"

So, in conclusion:

  • dirname $0 will give you the enclosing folder of the script in most situations
  • with zsh you can just use dirname ${0:A} to be even safer
  • when you have to use sh or bash, you can use a zsh one-liner: dirname $(zsh -c 'echo ${0:A}' "$0").

Happy Scripting!

(Remember to delete the symbolic link from /usr/local/bin/!)

Weekly News Summary for Admins — 2021-03-19

Fairly quiet week. No major news from Apple, except for the fourth beta of macOS 11.3, iOS 14.5 and siblings.

Apple has admitted that the original ‘large’ HomePod is discontinued. You can still buy them while supplies last. This seems like release some bad news before the good news. Apple often releases new products or updates at this time of year.


To support the weekly news summary, please consider:

macOS Terminal and Shell Book Cover

macOS Terminal and Shell:
You have always wanted to ‘learn Terminal,‘ right? This book teaches how (and why) to use the command line on macOS. Get it on Apple Books!


I have a list of upcoming conferences and dates on my website. The list also contains links where you can submit a session proposal and a link to the video archive of the conference, where available (this is new since last week).

PS: Don’t be alarmed. I will be experimenting with the layout of this newsletter over the next few weeks.

📰News and Opinion

🌅macOS 11 Big Sur and Apple silicon Macs

🐦MacAdmins on Twitter

  • Tim Perfitt: “I think I finally figured out how DFU in the M1 works. Apple says to: 1. Plug in to correct USB port to another mac running AC2. 2. hold power, left control option and right shift for 10 seconds 3. the release all but power button for another 10 seconds.” (Thread)

🔐Security and Privacy

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🤖Scripting and Automation

♻️Updates and Releases

📺To Watch

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📚 Support

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

EraseInstall application retired

It makes me very sad that the EraseInstall application has been retired.

We built this tool three years ago, mostly because we wanted to learn how to build an app like this on macOS. We think it worked out well. We learned a lot, and are glad the application was useful to some.

Since then, all the people involved in the EraseInstall Project have moved on to other jobs or other responsibilities. Unfortunately, this leaves us with no time or resources to maintain or improve EraseInstall.

The repository and the application will remain available in its current state. There will be no more updates. If someone feels they can take up the project and continue it, please do!

If you are looking for a similar solution, we recommend Graham Pugh’s eraseinstall script.

Thank you, all, again!

Team EraseInstall: Mischa van der Bent, Arnold Nefkens, and Armin Briegel

Weekly News Summary for Admins — 2021-03-12

Lots of news this week as macOS 11.2.3 and a iOS 14.4.1 dropped. Adobe is starting to ship Apple silicon versions of their software, but they are not universal apps. Git has a security issue with git clone, but no updated installer for macOS.

And I was on the MacAdmins Podcast and MacAdmins Monthly!

PSU MacAdmins have announced their schedule for another series of Campfire sessions this summer and MacDevOps YVR are calling for proposals! I have put the list I started last week on a page on my site. I plan to update that regularly.

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 and iOS Updates

MacAdmins on Twitter

  • Steve Troughton-Smith: “If you were confused by the matrix of SwiftUI, Catalyst and AppKit apps on macOS, it’s because this is what it looks like:” (Image)
  • Darren Wallace: “Mac Adobe Users seeing a new folder at ~/Documents/Library that you do not have permission to? Looks like a bug introduced for users who’s Creative cloud Desktop App (CCDA) updated from v5.3 > v5.4. Adobe are aware and a hot-fix is being worked on.”
  • Jason Broccardo: “#macadmins: Apple, please stop releasing supplemental updates that don’t change the OS build number as it creates confusion. Apple: Sure thing, we’ll require an OS update to patch Safari. Build number changes just like you asked.”
  • Nathaniel Strauss: “AutoPkg recipes updated for Google Drive 46.0.3. (AutoPkg recipes) Google is starting to ship Intel and Apple silicon versions side by side. Expect packages to be roughly double in size (~300 MB) with both included.”

Security and Privacy

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!