How to use the command 'open' (with examples)

The open command in macOS is a versatile utility that allows users to open files, directories, and applications from the command line. It’s particularly useful for automating tasks, integrating command-line usage into workflows that require graphical applications, and simplifying the user’s interaction with macOS’s graphical interface. The myriad ways to use open accommodate various user needs, from directly accessing files in their default applications to revealing files in Finder or launching applications via their bundle identifiers, enabling a seamless blend between GUI and terminal environments.

Use case 1: Open a file with the associated application

Code:

open file.ext

Motivation:

You’re working in a directory filled with files of different types and want to quickly open a document without navigating through the Finder. By using the open command, you can launch the file in its default application directly from the terminal, saving time and maintaining your workflow efficiency.

Explanation:

• file.ext: The file.ext represents the name of the file you wish to open. The .ext is a placeholder for the file’s extension, which helps the operating system determine which application to use for opening it. When you run this command, macOS automatically associates the file with its default application and opens it.

Example Output:

Executing this command opens the file in its default application. For example, if file.ext is a PDF document, it would likely open in Preview. There is no terminal output for this command; instead, you see the application window open and display your file.

Use case 2: Run a graphical macOS application

Code:

open -a "Application"

Motivation:

You might need to start an application without using your mouse or navigating through the Applications folder. This could be part of a script or simply for convenience while working within the terminal. The open -a command can be used to launch an application directly from the command line, making it easier and faster.

Explanation:

• -a: This option specifies that what follows is the name of the application you want to open. It tells open to look for an application by name instead of a file path.
• "Application": Here, you replace "Application" with the actual name of the application you wish to run, ensuring you include it in quotes if the name contains spaces.

Example Output:

Executing this command opens the specified application. For example, open -a "TextEdit" would open a new instance of the TextEdit application. Like the previous example, there is no terminal output as the application launches in its own window.

Use case 3: Run a graphical macOS app based on the bundle identifier

Code:

open -b com.domain.application

Motivation:

Applications might have multiple versions or configurations, and identifying them by their bundle identifier might be necessary for precise control. The bundle identifier is a unique string assigned to each application on macOS, ensuring the exact application is opened.

Explanation:

• -b: This option is used to specify the bundle identifier of an application instead of its name. It can be particularly useful when there are several applications with similar names.
• com.domain.application: This placeholder should be replaced with the actual bundle identifier of the application you wish to open. The bundle identifier is found in the application’s package contents or via utilities like osascript.

Example Output:

When this command is executed, it launches the application associated with the specified bundle identifier. The application opens in its usual graphical interface with no additional terminal output.

Use case 4: Open the current directory in Finder

Code:

open .

Motivation:

When navigating through directories using the terminal, you might prefer to switch to a visual interface for certain tasks, such as dragging and dropping files. This command opens your current working directory in Finder, allowing you to visually interact with its contents.

Explanation:

• .: The period represents the current directory in Unix-like systems. By using open ., you are instructing the system to open the Finder application at your current directory location.

Example Output:

After executing this command, a Finder window opens displaying the contents of the directory you were in. This way, you can easily interact with files and directories in a more familiar graphical environment.

Use case 5: Reveal a file in Finder

Code:

open -R path/to/file

Motivation:

Locating a file within Finder can sometimes be cumbersome if you’re dealing with a large number of files or nested directories. By using this command, you can directly reveal the path of a specific file in Finder, making it easy to access, move, or review.

Explanation:

• -R: This flag stands for “reveal,” indicating that instead of opening the file, Finder should show its location.
• path/to/file: Replace this with the complete path to the file you want to reveal. The system will navigate to this location within Finder and highlight the file for you.

Example Output:

The Finder application opens, and it navigates to the directory containing the file. Within this directory, the file is automatically highlighted, allowing for quick access to file management options.

Use case 6: Open all the files of a given extension in the current directory with the associated application

Code:

open *.ext

Motivation:

If you frequently work with files of the same type and need to open them simultaneously, using a wildcard with the open command can save time and effort. It’s especially handy when you need to quickly access multiple documents, images, or any other file type.

Explanation:

• *.ext: The asterisk (*) is a wildcard character that matches any file with the extension specified by .ext. It tells the system to open all files within the current directory that end with this extension.

Example Output:

Upon execution, all files within the current directory that match the specified extension open in their default associated applications. If you specified .jpg for the extension, all image files with a .jpg extension would be opened in the default image viewer assigned by the system.

Use case 7: Open a new instance of an application specified via bundle identifier

Code:

open -n -b com.domain.application

Motivation:

Sometimes, you might need multiple instances of the same application running simultaneously, especially for productivity tools like browsers or text editors. Using this command allows you to bypass restrictions on single instances and open a completely new application window.

Explanation:

• -n: This flag allows opening a new instance of the application, rather than bringing the existing instance to focus. It facilitates running multiple sessions of the same app.
• -b: Specifies the application by its bundle identifier.
• com.domain.application: This placeholder should be replaced with the specific bundle identifier of the application you want to open a new instance for.

Example Output:

After executing the command, a new instance of the specified application opens, allowing for separate task management or project handling. This is useful if, for example, you want to run two completely separate browsing sessions in Safari.

Conclusion:

The open command on macOS serves as a powerful tool to bridge command-line operations with the graphical features of the operating system. Its versatility, reflected in the various use cases discussed, empowers users to handle files and applications with precision and efficiency. Whether opening files directly from the terminal, navigating to directories in Finder, or managing application instances, open provides practical solutions for a wide array of tasks. By leveraging the command’s potential, users can enjoy an improved workflow, seamlessly transitioning between command-line inputs and graphical outputs.