shell-picker can be used as a Custom Shell or start-up Command for an iTerm2 Profile on macOS Apple Silicon to automatically pick the real shell for the desired architecture arm64 or x86_64 running in Rosetta 2.
macOS on Apple Silicon currently provides ability to run 2 architectures: arm64 and (using Rosetta 2) x86_64 for legacy applications that have not yet migrated to arm64 platform. This provides a bit of a challenge for development, when the development tools and utilities are not yet converted.
An example use case is Tableau Hyper API, which after many years, only supports x86_64. While the simplified instructions in the Hyper API installation documentation makes note of running python on Rosetta (arch -x86_64 /usr/bin/python3 ...), development would generally require a more than just being able to run python. Preferably getting a dedicated shell to run x86_64 and everything else in the tool-chain needed to created and validate (in iTerm2) needs a bit more.
Running in iTerm2 with some of the fancy, and at times helpful, zsh plugins requires some setup that is more easily done with Homebrew, or other package managers - for both arm64 and x86_64. Out of the box, iTerm2 uses the user's login shell, which by default in macOS is /bin/zsh. This build of zsh is a universal app, and works just fine running either out or inside Rosetta. However, the underlying plugins from brew won't work if they are sourced in x86_64 but for arm64 causing extra debugging.
The shell-picker universal command can be configured and used by iTerm2 as the Custom Shell which is a Profile setting. When iTerm2 is launched normally, shell-picker determines the architecture is arm64, and either run the default arm64 Homebrew zsh shell at /opt/homebrew/bin/zsh or whatever is configured in ~/.config/shell-picker.conf. But when iTerm2.app is duplicated (e.g. iTerm2_x86_64.app) and configured to be run using Rosetta2, shell-picker will instead start zsh in Homebrew x86_64 default location /usr/local/bin/zsh, or again whatever is configured in ~/.config/shell-picker.conf. Which may also be a bash, fish, ksh or other shell.
Any parameters passed to shell-picker are passed to the real shell being run. However, if -v or --verbose is passed to shell-picker, then it will print the running system architecture to stdout. Since zsh outputs a lot of information with -v or --verbose parameter, it is best to redirect stderr to /dev/null if not interested: shell-picker -v 2>/dev/null.
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Download the code either by grabbing the source zip and putting in directory of your choice, or cloning the git repository.
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Ensure that minimal development tools such as xcode command line tools are installed.
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Build the program by running
makein the source directory. -
Copy the compiled program from the
buildsubdirectory to path of choice. -
Edit (if needed) and copy the
shell-picker.conffile to~/.config/directory. -
Back-up by exporting your current Default Profile.
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Install iTerm2 either directly from iTerm2 website, or through Homebrew
brew install iterm2. -
From
/Applicationsdirectory, copyiTerm2.apptoiTerm2_x86_64.app. -
In
Finder, highlightiTerm2_x86_64.appthat was just copied and Get Info either from the menu, or using⌘+ishortcut. Only do this foriTerm2_x86_64.appand notiTerm2.app.
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In the Info dialog, check Open using Rosetta checkbox.
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Open
iTerm2.app. -
In Settings (
⌘+,), configure the default or desired profile in iTerm2 to useshell-pickerby setting the full path forshell-pickerin the Command section as a Custom Shell (or Command drop-down option).
Since the same iTerm2 Profiles are used for both copies of iTerm2*.app, then only need to configure
shell-pickeronce. -
Completely stop all instances and restart iTerm2 (including any background
iTerm2Serverprograms) or may get error starting.
After validating, and configuring your .zshrc for either arm64 and x86_64, finish by installing extra tooling, like Homebrew and necessary packages, in the x86_64 shell. Luckily Homebrew uses separate directories and installation instances between the two architectures: /opt/homebrew for Apple Silicon arm64 and /usr/local for macOS Intel x86_64.