👉 Overview
👀 What ?
macOS File Extension & URL scheme app handlers are methods used by macOS to determine which application will open a particular file or URL. File extensions are used to identify the type of file, and the associated app handler is the application that macOS will use to open the file. URL scheme app handlers are used to handle specific URL schemes.
🧐 Why ?
Understanding macOS File Extension & URL scheme app handlers is essential because they are integral to how macOS operates. When a user double-clicks on a file, macOS uses the file extension to determine which application to open the file with. Similarly, when a URL is clicked, macOS uses the URL scheme to decide which application to handle the URL. Incorrect or malicious handling of these can lead to significant issues, including data loss, application errors, or security vulnerabilities.
⛏️ How ?
To view or change the default file handler for a particular file extension, right-click on a file of that type, select 'Get Info', and then under 'Open with', select the app you want to use. To view or change the URL scheme handler, you need to delve into macOS’s internal database using a command-line tool. This can be complex and is not recommended without a solid understanding of macOS internals.
⏳ When ?
macOS has used file extensions and URL scheme app handlers since its inception, as they are fundamental parts of how the operating system interacts with applications and files.
⚙️ Technical Explanations
File extensions are a method of identifying the type of a file. They are typically a few characters long and start with a period. For example, '.txt' is the extension for text files and '.jpg' is the extension for JPEG image files. macOS uses this extension to determine which application should be used to open the file.\n\nURL scheme app handlers are a bit more complex. They are used to handle specific URL schemes. For example, 'http:' and 'https:' URLs are handled by your web browser, 'mailto:' URLs are handled by your email client, and so on. This is determined by a database stored within macOS that pairs URL schemes with applications.\n\nChanging the default handler for a file extension or URL scheme can have unintended consequences. For example, changing the handler for '.jpg' to a text editor would result in an attempt to open JPEG files in the text editor, which would not be able to correctly interpret the data. Similarly, changing the handler for 'http:' URLs to an application that does not understand how to handle web pages could result in errors when trying to open web links.\n\nIn a cybersecurity context, a malicious application could potentially change these handlers to redirect files or URLs to itself, potentially enabling data theft or other exploits. As such, understanding and correctly managing file extension and URL scheme handlers is important for maintaining the security and correct operation of a macOS system.