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16.3.10. Modifying Existing Printers

To delete an existing printer, in the Printer Configuration window, select the printer and go to PrinterDelete. Confirm the printer deletion. Alternatively, press the Delete key.
To set the default printer, right-click the printer in the printer list and click the Set As Default button in the context menu. The Settings Page

To change printer driver configuration, double-click the corresponding name in the Printer list and click the Settings label on the left to display the Settings page.
You can modify printer settings such as make and model, print a test page, change the device location (URI), and more.
Settings page
Settings Page
Figure 16.11. Settings page The Policies Page

Click the Policies button on the left to change settings in printer state and print output.
You can select the printer states, configure the Error Policy of the printer (you can decide to abort the print job, retry, or stop it if an error occurs).
You can also create a banner page (a page that describes aspects of the print job such as the originating printer, the username from the which the job originated, and the security status of the document being printed): click the Starting Banner or Ending Banner drop-menu and choose the option that best describes the nature of the print jobs (such as topsecret, classified, or confidential). Sharing Printers
On the Policies page, you can mark a printer as shared: if a printer is shared, users published on the network can use it. To allow the sharing function for printers, go to ServerSettings and select Publish shared printers connected to this system.
Finally, ensure that the firewall allows incoming TCP connections to port 631, which is Network Printing Server (IPP) in system-config-firewall.
Policies page
Policies Page
Figure 16.12. Policies page The Access Control Page
You can change user-level access to the configured printer on the Access Control page. Click the Access Control label on the left to display the page. Select either Allow printing for everyone except these users or Deny printing for everyone except these users and define the user set below: enter the user name in the text box and click the Add button to add the user to the user set.
Access Control page
Access Control Page
Figure 16.13. Access Control page The Printer Options Page
The Printer Options page contains various configuration options for the printer media and output, and its content may vary from printer to printer. It contains general printing, paper, quality, and printing size settings.
Printer Options page
Printer Options Page
Figure 16.14. Printer Options page Job Options Page
On the Job Options page, you can detail the printer job options. Click the Job Options label on the left to display the page. Edit the default settings to apply custom job options, such as number of copies, orientation, pages per side,scaling (increase or decrease the size of the printable area, which can be used to fit an oversize print area onto a smaller physical sheet of print medium), detailed text options, and custom job options.
Job Options page
Job Options Page
Figure 16.15. Job Options page Ink/Toner Levels Page
The Ink/Toner Levels page contains details on toner status if available and printer status messages. Click the Ink/Toner Levels label on the left to display the page.
Ink/Toner Levels page
Ink/Toner Levels Page
Figure 16.16. Ink/Toner Levels page Managing Print Jobs

When you send a print job to the printer daemon, such as printing a text file from Emacs or printing an image from GIMP, the print job is added to the print spool queue. The print spool queue is a list of print jobs that have been sent to the printer and information about each print request, such as the status of the request, the job number, and more.
During the printing process, messages informing about the process appear in the notification area.
GNOME Print Status
GNOME Print Status
Figure 16.17. GNOME Print Status

To cancel, hold, release, reprint or authenticate a print job, select the job in the GNOME Print Status and on the Job menu, click the respective command.
To view the list of print jobs in the print spool from a shell prompt, type the command lpstat -o. The last few lines look similar to the following:
Example 16.1. Example of lpstat -o output
$ lpstat -o
Charlie-60              twaugh            1024   Tue 08 Feb 2011 16:42:11 GMT
Aaron-61                twaugh            1024   Tue 08 Feb 2011 16:42:44 GMT
Ben-62                  root              1024   Tue 08 Feb 2011 16:45:42 GMT

If you want to cancel a print job, find the job number of the request with the command lpstat -o and then use the command cancel job number. For example, cancel 60 would cancel the print job in Example 16.1, “Example of lpstat -o output”. You cannot cancel print jobs that were started by other users with the cancel command. However, you can enforce deletion of such job by issuing the cancel -U root job_number command. To prevent such canceling, change the printer operation policy to Authenticated to force root authentication.
You can also print a file directly from a shell prompt. For example, the command lp sample.txt prints the text file sample.txt. The print filter determines what type of file it is and converts it into a format the printer can understand.