M1 Mac — How to switch the Terminal between x86_64 and arm64

Here is a simple writeup on how I switch between x86_64 and arm64 in the Terminal app on my MacBook Pro with Apple Silicon.

So you have the new Mac with Apple Silicon. However, a lot of your projects are compiled in x86 and/or you are still building apps for x86, or whatever it is, you still want to compile the x86_64 code on your new Mac in the Terminal. You know it is possible with the Rosetta 2 (personally love it!). But how do you do it efficiently?

While there are many ways of doing it, the following is the best one I have found to easily switch between the two architectures using just a simple Terminal command as below (actually hiding the command under an alias)..

switching efficiently between x86_64 and arm64 using created alias

So let’s look at what’s behind it, and how you too can easily set it up!

The main command which does the magic is the one below:

$env /usr/bin/arch -<architecture> /bin/zsh --login

… just replace the <architecture> with your preferred one..

For example:

• To see your current architecture, type:

$arch

see current architecture the Terminal is using

As we see in the image above, I am currently using arm64, hence any code I compile will be for this architecture.

• To switch to x86_64, type:

$env /usr/bin/arch -x86_64 /bin/zsh —-login

Now if you type the arch command again, you will see that the target architecture has been changed. Now you can go ahead and compile your code using Rosetta 2 for the x86_64 architecture.

Creating alias in .zshrc:

I don’t want to remember the whole command and type it all the time (obviously it’s not efficient). The simplest solution is to create an alias to it in the .zshrc

Just cd into your home directory and open the .zshrc file.. If you don’t have one, you can easily create it using the touch command. (If you don’t know about it, there are already plenty of tutorials/write-ups online)..

Here’s how my .zshrc file looks like.. I have named my aliases arm and intel for the arm and x86_64 architectures respectively. You can name your aliases whatever you want. Just remember to relaunch the Terminal after updating and saving the .zshrc file.

adding alias to .zshrc

Ignoring the first line, you can see the two alias I have created for arm and intel. To switch, I just need to type the alias and that’s it!

Bonus:

If you only want to use the Terminal app with Rosetta 2 for the x86_64 architecture, you can simple right click on the Terminal app in the Applications>Utilities, go the ‘Get Info’ and tick on “Open using Rosetta”