cupsd

Manage CUPS printing service

TLDR

Start cupsd in the background, aka. as a daemon

$ cupsd

Start cupsd on the [f]oreground

$ cupsd -f

[l]aunch cupsd on-demand (commonly used by launchd or systemd)

$ cupsd -l

Start cupsd using the specified [c]upsd.conf configuration file

$ cupsd -c [path/to/cupsd.conf]

Start cupsd using the specified cups-file[s].conf configuration file

$ cupsd -s [path/to/cups-files.conf]

[t]est the [c]upsd.conf configuration file for errors

$ cupsd -t -c [path/to/cupsd.conf]

[t]est the cups-file[s].conf configuration file for errors

$ cupsd -t -s [path/to/cups-files.conf]

Display help

$ cupsd -h

-c cupsd.conf
    Specifies the configuration file to use. Defaults to /etc/cups/cupsd.conf.

-t
    Tests the configuration file for syntax errors. Does not start the daemon.

-v
    Shows the CUPS version and exits.

DESCRIPTION

cupsd is the core of the Common UNIX Printing System (CUPS). It is the daemon that handles print jobs, manages printers, and provides network printing services.
It listens for print requests, processes them, and sends them to the appropriate printer. It also provides a web interface for managing printers and print jobs.
The cupsd daemon reads its configuration from the cupsd.conf file, which defines the printers, policies, and other settings for the print server.
It is a crucial component for printing functionality in most Linux and macOS systems, enabling both local and networked printing. Proper configuration of cupsd is essential for reliable and secure printing services.

CAVEATS

Incorrect configuration of cupsd can lead to printing failures or security vulnerabilities. Ensure that the cupsd.conf file is properly configured and secured.

SIGNAL HANDLING

cupsd responds to various signals. SIGHUP causes cupsd to reload its configuration file. SIGTERM and SIGINT cause cupsd to shutdown gracefully.

WEB INTERFACE

cupsd provides a web interface, typically accessible at http://localhost:631, for managing printers and jobs.

HISTORY

CUPS was originally developed by Easy Software Products and later acquired by Apple Inc. It has become the standard printing system on most Linux distributions and macOS. cupsd is the main daemon introduced with CUPS which replaced older and incompatible printer subsystems. It has evolved over time to support new printing protocols, security features, and printer technologies.