The first time printing to a printer, CUPS creates a queue to keep track of the current status of the printer and any pages you have printed. Most of the time the queue points to a printer connected directly to your computer via a USB port, however it can also point to a printer on your network, a printer on the Internet, or multiple printers depending on the configuration. Regardless of where the queue points, it will look like any other printer to you and your applications. Every time you print something, CUPS creates a job which contains the queue you are sending the print to, the name of the document you are printing, and the page descriptions. Job are numbered (queue-1, queue-2, and so forth) so you can monitor the job as it is printed or cancel it if you see a mistake. When CUPS gets a job for printing, it determines the best programs (filters, printer drivers, port monitors, and backends) to convert the pages into a printable format and then runs them to actually print the job. When the print job is completely printed, CUPS removes the job from the queue and moves on to any other jobs you have submitted. You can also be notified when the job is finished, or if there are any errors during printing, in several different ways. configure printer: (mac "cupsctl Weblnterface=yes" ) http://localhost:631 and choose the Administration tab at the top of the page. Click/press on the Add Printer button and follow the prompts. Open system preferences. Go to Security & Privacy > Firewall. Unlock your padlock with your system password. lock your padlock again... https://discussions.apple.com/thread/252638638 After the printer is added you will be asked to set the default printer options (paper size, output mode, etc.) for the printer. Make any changes as needed and then click/press on the Set Default Options button to save them. Some printers also support auto-configuration - click/press on the Query Printer for Default Options button to update the options automatically. print to it from any application. You can also choose Print Test Page from the maintenance menu to print a simple test page and verify that everything is working properly. You can also use the lpadmin(8) and lpinfo(8) commands to add printers to CUPS. Additionally, your operating system may include graphical user interfaces or automatically create printer queues when you connect a printer to your computer. HOW DO I GET HELP? The CUPS web site (http://www.CUPS.org) provides access to the cups and cups-devel mailing lists, additional documentation and resources, and a bug report database. Most vendors also provide online discussion forums to ask printing questions for your operating system of choice. ENVIRONMENT CUPS commands use the following environment variables to override the default locations of files and so forth. For security reasons, these environment variables are ignored for setuid programs: CUPS_ANYROOT Whether to allow any X.509 certificate root (Y or N). CUPS_CACHEDIR The directory where semi-persistent cache files can be found. CUPS_DATADIR The directory where data files can be found. CUPS_ENCRYPTION The default level of encryption (Always, IfRequested, Never, Required). CUPS_EXPIREDCERTS Whether to allow expired X.509 certificates (Y or N). CUPS_GSSSERVICENAME The Kerberos service name used for authentication. CUPS_SERVER The hostname/IP address and port number of the CUPS scheduler (hostname:port or ipaddress:port). CUPS_SERVERBIN The directory where server helper programs, filters, backend, etc. can be found. CUPS_SERVERROOT The root directory of the server. CUPS_STATEDIR The directory where state files can be found. CUPS_USER Specifies the name of the user for print requests. HOME Specifies the home directory of the current user. IPP_PORT Specifies the default port number for IPP requests. LOCALEDIR Specifies the location of localization files. LPDEST Specifies the default print queue (System V standard). PRINTER Specifies the default print queue (Berkeley standard). TMPDIR Specifies the location of temporary files.