cups-driverd

cups-driverd (usually managed by cupsd)

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    Note: cups-driverd is an internal CUPS daemon and does not expose user-facing command-line options. Any parameters are typically for internal debugging or specific operational modes managed by cupsd itself.

The cups-driverd command is an internal daemon component of the Common Unix Printing System (CUPS). Its primary role is to manage and provide information about installed printer drivers and PostScript Printer Description (PPD) files to the main CUPS scheduler, cupsd. It scans predefined locations for PPD files and other driver components, processes them, and makes this driver information available for printer setup and configuration. Essentially, cups-driverd acts as a backend service for driver discovery and enumeration, allowing users and applications to find and select appropriate drivers when adding new printers or modifying existing ones.

Users typically do not interact with cups-driverd directly; it is automatically started, stopped, and managed by the cupsd daemon or the system's init system (e.g., systemd). Its correct operation is crucial for the CUPS system to identify and utilize the vast array of available printer drivers, ensuring seamless printing functionality. Issues with cups-driverd can manifest as problems with printer discovery or the inability to select specific printer features.

Because cups-driverd is an internal CUPS daemon, it is not intended for direct user execution. Attempting to run it manually may lead to unexpected behavior or conflicts with the running CUPS service. Troubleshooting issues related to driver discovery often involves checking the logs of the main cupsd daemon (e.g., /var/log/cups/error_log) and ensuring that PPD files and driver binaries are correctly installed and have appropriate permissions.

Malfunctions of cups-driverd can prevent new printers from being added or correctly configured, as the system relies on it to enumerate available drivers.

cups-driverd largely deals with PostScript Printer Description (PPD) files. PPD files are text files that describe the capabilities and features of a PostScript printer, including supported resolutions, paper sizes, and options for things like duplexing or collating. cups-driverd parses these files and presents the information in a structured way to CUPS, allowing the system to correctly configure and interact with a wide range of printers.

cups-driverd functions as a helper daemon for cupsd, the main CUPS scheduler. When a request comes in to add or configure a printer, or to list available drivers, cupsd queries cups-driverd to retrieve the necessary driver information. This architectural separation allows for modularity and efficient management of driver data without burdening the main scheduler with parsing and managing all driver files directly.

The Common Unix Printing System (CUPS) was initially developed by Michael Sweet and released by Easy Software Products in 1999. It quickly became the de facto standard printing system for Unix-like operating systems. Apple Inc. acquired CUPS in 2007, continuing its development. cups-driverd has been a fundamental component of the CUPS architecture since its early days, tasked with managing printer drivers and PPD files. While CUPS has evolved to support driverless printing technologies like AirPrint and IPP Everywhere, the role of cups-driverd remains vital for supporting traditional PPD-based drivers and providing comprehensive driver information within the CUPS ecosystem.

cupsd(8), lpadmin(8), lpstat(1), printers.conf(5), cups-files.conf(5), systemd(1)