Running Multiple Instances of the Same Application on macOS X

Contrary to popular belief, macOS X allows users to run multiple instances of the same application. This feature, although not commonly needed, offers a solution for scenarios where a single instance of an application is insufficient. Let's explore how to achieve this using both the graphical user interface (GUI) and the command line.

Understanding macOS and Application Instances

Unlike some other operating systems like Windows, macOS manages application instances in a unique way. On macOS, an application can open an arbitrary number of files each in its own separate window. This design simplifies many tasks and makes it unnecessary to run multiple instances of an app. However, there are instances where running multiple instances would be beneficial.

Using the Command Line to Run Instances

One of the easiest ways to run multiple instances of an application is by using the command line. By appending an ampersand () to your command, you instruct the system to run the program in the background in a subshell. This technique can be used to run the same application multiple times.

For example, consider the following scenario:

#!/bin/bashecho "Running script"sleep 5echo "Ending script"

To run this script, you can use the following command:

bash

When you run this command, the command prompt will immediately appear, even if the script is still running in the background.

Using the Graphical User Interface (GUI)

Most applications designed for multiple instances will provide a menu or a preference option to launch a new instance. Open the application and look for an option in the menubar that allows you to create a new instance. This method is more intuitive and user-friendly.

For example, on macOS, you can open another instance of Safari using the following command in the terminal:

open -n

The -n flag instructs macOS to launch a new, separate instance of Safari.

Custom Command-Line Launches

Not all applications come with a built-in mechanism to launch multiple instances. In such cases, you can use the open command in the terminal to achieve this. For instance, if you’re working with a custom application, you might need to use a specific command to launch it.

Locate the application’s command-line entry point.

Use the open -n command followed by the path to the application.

For example, if your application is located at /path/to/your/executable, you can launch a new instance with the following command:

open -n /path/to/your/executable

Conclusion

While running multiple instances of the same application is not a common task on macOS, it is still a capability of the operating system. It is primarily useful in specific scenarios and can be achieved using both GUI and command-line methods. Always ensure that the app supports multiple instances before attempting to run them.

Whether you need to keep multiple instances of an app open due to system limitations or just for personal convenience, understanding how to do it provides a valuable tool in your command-line arsenal.