Packaging – Page 2 – Scripting OS X

Check Installer Pkgs for deprecated scripts

macOS 10.15 Catalina will deprecate the built-in /bin/bash. I have talked about this at length.

The release notes for Catalina also tell us that other built-in scripting runtimes, namely Python, Perl, and Ruby. Will not be included in future macOS releases (post-Catalina) any more.

This means, that if you want to use bash, Python, Perl, or Ruby on macOS, you will have to install, and maintain your own version in the future.

However, scripts in installation packages, cannot rely on any of these interpreters being available in future, post-Catalina versions of macOS. Installer pkgs can be run in all kinds of environments and at all times, and you would not want them to fail, because a dependency is missing.

The good news is that we still have time. All the runtimes mentioned above are still present in Catalina, so the packages will continue to work for now. But if you are building installation scripts, you need to check if any of the installation scripts use one of these interpreters and fix them.

I recommend to use /bin/sh for installation scripts, since that will run in any macOS context, even the Recovery system.

If you are using third-party installer packages, you may also want to check them for these interpreters, and notify the developer that these packages will break in future versions of macOS.

To check a flat installer package, you would expand it with pkgutil --expand and then look at script files in the Scripts folder. This will work fine for a package or two, but gets tedious really quickly, especially with large distribution pkgs with many components (e.g. Office).

So… I wrote a script to do it. The script should handle normal component pkgs, distribution pkgs and the legacy bundle pkgs and mpkgs.

You can get the pkgcheck script from my Github repo.

What the script does

Once I had written the code to inspect all these types of pkgs, I realized I could grab all other kinds of information, as well. The pkgcheck.sh script will check for:

Signature and Notarization
Type of Package: Component, Distribution, legacy bundle or mpkg
Identifier and version (when present)
Install-location
for Distribution and mpkg types, shows the information for all components as well
for every script in a pkg or component, checks the first line of the script for shebangs of the deprecated interpreters (/bin/bash, /usr/bin/python, /usr/bin/perl, and /usr/bin/ruby) and print a warning when found

How to run pkgcheck.sh

Run the script with the target pkg file as an argument:

% ./pkgcheck.sh sample.pkg

You can give more than one file:

% ./pkgcheck.sh file1.pkg file2.pkg ...

When you pass a directory, pkgcheck.sh will recursively search for all files or bundle directories with the pkg or mpkg extension in that directory:

% ./pkgcheck.sh SamplePkgs

Features and Errors

There are a few more things that I think might be useful to check in this script. Most of all, I want to add an indicator whether a component is enabled by default or not. If you can think of any other valuable data to display, let me know. (Issue or Pull Request or just ping me on MacAdmins Slack)

I have tested the script against many pkgs that I came across. However, there are likely edge cases that I haven’t anticipated, which might break the script. If you run into any of those, let me know. (File an Issue or Pull Request.) Having the troublesome pkg would of course be a great help.

Note: the script will create a scratch directory for temporary file extractions. The script doesn’t actually expand the entire pkg file, only the Scripts sub-archive. The scratch folder will be cleaned out at the beginning of the next run, but not when the script ends, as you might want to do some further inspections.

Sample outputs

This is a sample pkg I build in my book, it has pre- and postinstall scripts using a /bin/bash shebang:

% ./pkgcheck.sh SourceCodePro-2.030d.pkg
SourceCodePro-2.030d
SamplePkgs/SourceCodePro-2.030d.pkg
Signature:      None
Notarized:      No
Type:           Flat Component PKG
Identifier:     com.example.SourceCodePro
Version:        2.030d
Location:       /
Contains 2 resource files
postinstall has shebang #!/bin/bash
preinstall has shebang #!/bin/bash

This is the experimental notarized pkg installer for desktoppr:

% ./pkgcheck.sh desktoppr-0.2.pkg
desktoppr-0.2
SamplePkgs/desktoppr-0.2.pkg
Signature:      Developer ID Installer: Armin Briegel (JME5BW3F3R)
Notarized:      Yes
Type:           Flat Component PKG
Identifier:     com.scriptingosx.desktoppr
Version:        0.2
Contains 0 resource files

And finally, this is a big one, the Microsoft Office installer: (they have some work to do to clean up those scripts)

% ./pkgcheck.sh Microsoft\ Office\ 16.27.19071500_Installer.pkg
Microsoft Office 16.27.19071500_Installer
SamplePkgs/Microsoft Office 16.27.19071500_Installer.pkg
Signature:      Developer ID Installer: Microsoft Corporation (UBF8T346G9)
Notarized:      No
Type:           Flat Distribution PKG
Contains 11 component pkgs

    Microsoft_Word_Internal
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Microsoft_Word.app
    Version:        16.27.19071500
    Location:       /Applications
    Contains 3 resource files

    Microsoft_Excel_Internal
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Microsoft_Excel.app
    Version:        16.27.19071500
    Location:       /Applications
    Contains 2 resource files

    Microsoft_PowerPoint_Internal
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Microsoft_PowerPoint.app
    Version:        16.27.19071500
    Location:       /Applications
    Contains 2 resource files

    Microsoft_OneNote_Internal
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Microsoft_OneNote.app
    Version:        16.27.19071500
    Location:       /Applications
    Contains 2 resource files

    Microsoft_Outlook_Internal
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Microsoft_Outlook.app
    Version:        16.27.19071500
    Location:       /Applications
    Contains 2 resource files

    OneDrive
    Type:           Flat Component PKG
    Identifier:     com.microsoft.OneDrive
    Version:        19.70.410
    Location:       /Applications
    Contains 30 resource files
    postinstall has shebang #!/bin/bash
    od_logging has shebang #!/bin/bash
    od_service has shebang #!/bin/bash
    od_migration has shebang #!/bin/bash
    preinstall has shebang #!/bin/bash

    Office16_all_autoupdate
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Microsoft_AutoUpdate.app
    Version:        4.13.19071500
    Location:       /Library/Application Support/Microsoft/MAU2.0
    Contains 2 resource files
    postinstall has shebang #!/bin/bash
    preinstall has shebang #!/bin/bash

    Office16_all_licensing
    Type:           Flat Component PKG
    Identifier:     com.microsoft.pkg.licensing
    Version:        16.27.19071500
    Location:       /
    Contains 2 resource files
    dockutil has shebang #!/usr/bin/python

    Office_fonts
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.DFonts
    Version:        0
    Location:       /private/tmp/com.microsoft.package.DFonts
    Contains 1 resource files
    postinstall has shebang #!/bin/bash

    Office_frameworks
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Frameworks
    Version:        0
    Location:       /private/tmp/com.microsoft.package.Frameworks
    Contains 1 resource files
    postinstall has shebang #!/bin/bash

    Office_proofing
    Type:           Flat Component PKG
    Identifier:     com.microsoft.package.Proofing_Tools
    Version:        0
    Location:       /private/tmp/com.microsoft.package.Proofing_Tools
    Contains 1 resource files
    postinstall has shebang #!/bin/bash

Install Bash 5 on macOS with Patches

I recently posted an article on how to download, install, and build a macOS installer pkg for bash 5. In that first version of this post I ignored patches, minor updates to the bash source code and binary. But as the patches to bash 5 are accumulating, I cannot ignore them much longer.

This post will extend the instructions in the original post.

After downloading and expanding the bash-5.0.tar.gz, create a patches folder:

$ cd path/to/bash-5.0
$ mkdir patches
$ cd patches

You can download the patches for bash-5.0 here. As of this writing, there are seven patches for bash-5.0 labelled bash50-001 through bash50-007. You can download all at once with:

$ curl 'https://ftp.gnu.org/gnu/bash/bash-5.0-patches/bash50-[001-007]' -O

(Adapt the numbers when there are more patches in the future.)

Then move up one directory level to the bash-5.0 root directory and apply the patches using the patch command.

$ cd ..
$ patch -p0 -i patches/bash50-001
$ patch -p0 -i patches/bash50-002

(etc.)

You can download and patch with a single step. Make sure your working directory is the bash-5.0 with all the code and run:

$ curl 'https://ftp.gnu.org/gnu/bash/bash-5.0-patches/bash50-[001-007]' | patch -p0

From here, you can continue with the remaining build steps from the original post. The next step will be running ./configure.

The script to build the pkg installer has also been updated in the repository to download and apply the patches before building.

Build Simple Packages with Scripts

In a past post, I described how path_helper works. As an example, I mentioned the installer for Python 3 which runs a postinstall script that locates and modifies the current user’s shell profile file to add the Python 3 binary directory to the PATH.

Not only is modifying a user’s file a horrible practice, but it will not achieve the desired purpose when the user installing the package is ultimately not the user using the system. This setup happens fairly frequently in managed deployment workflows.

As described in the earlier post, macOS will add the contents of files in /etc/paths.d/ to all users’ PATHs. So, all we have to do is create a file with the path to the Python 3 binary directory in /etc/paths.d/. A perfect task for a simple installer package.

The steps to create such an installer are simple:

$ mkdir -p Python3PathPkg/payload
$ cd Python3PathPkg
$ echo "/Library/Frameworks/Python.framework/Versions/3.7/bin" > payload/Python-3.7
$ pkgbuild --root payload --install-location /private/etc/paths.d --version 3.7  --identifier com.example.Python3.path Python3Path-3.7.pkg
pkgbuild: Inferring bundle components from contents of payload
pkgbuild: Wrote package to Python3Path-3.7.pkg

This is not so hard. However, since the path to binary contains the major and minor version number, you will have to create a new version when Python 3 updates to 3.8 (and 3.9, etc…).

So, it makes sense to script the process. With a package this simple, you can create everything required to build the package (i.e. the payload folder with contents) from the script in a temporary directory and then discard it after building.

You can find my script at this Github repository.

Note: when you modify the PATH with path_helper, your additions will be appended. The Python 3 installer prepends to the PATH. This might lead to slightly different behavior, as the Python 3 behavior overrides any system binaries. If you want to prepend for every user, you have to modify the /etc/paths file.

There are a few other simple installers where this approach makes sense. I also made a script that builds a package to create the .AppleSetupDone file in /var/db to suppress showing the setup assistant at first boot. Since I was planning to use this with the startosinstall --installpackage option, this script builds a product archive, rather than a flat component package.

You could create this package once and hold on to it whenever you need it again, but I seem to keep losing the pkg files. The script allows you to easily re-build the package in a different format or sign it when necessary. Also, dealing with the invisible file is a bit easier when you just create them on demand.

The last example creates a single invisible file .RunLanguageChooserToo, also in /var/db/. This will show an additional dialog before the Setup Assistant to choose the system language. MacAdmins might want to have this dialog for the obvious reason, but it also allows for a useful hack. When you invoke the Terminal at the Language Chooser with ctrl-option-command-T it will have root privileges, which allows some interesting workflows.

With this package the creation of the flag file happens too late to actually show the chooser. So I added the necessary PackageInfo flags to make the installer require a restart. Note that startosinstall will only respect this flag with a Mojave installer, not with High Sierra.

These three scripts can be used as templates for many similar use cases. As your needs get more complex, you should move to pkgbuild scripts with a payload folder, munkipkg, or Whitebox Packages.

You can learn about the details of inspecting and building packages in my book: “Packaging for Apple Administrators”