ioreg

ioreg is a command-line utility found on macOS and other Darwin-based operating systems that displays information about the system's I/O Registry. The I/O Registry is a database that describes the hardware and software components of the system and their relationships. It's a tree-like structure where each node represents a device, driver, or other kernel object.

The ioreg command allows users to navigate and inspect this registry. By default, it prints the entire registry to the standard output. Users can specify a specific node to query, and can also use various flags to filter and format the output. Common uses include examining hardware configurations, debugging driver issues, and understanding how devices are connected and managed by the operating system.

The output of ioreg can be quite verbose, containing details such as device properties, driver connections, and interrupt information. It's an essential tool for system administrators, developers, and anyone needing to deeply understand the hardware and software interactions on a Darwin system. For example, one might use ioreg to confirm if a specific hardware device is recognized by the kernel and which driver is associated with it.