Command-Line Printer Administration

Command-Line Printer Administration

Introduction

Destinations are individual printers and classes (pools) of printers. Printers use a description file with one or more driver ("filter") programs that communicate with the printer through a "backend" program. CUPS currently uses PPD (PostScript Printer Description) files to describe the printer and driver programs needed, some of which come with CUPS while others come with your operating system or Linux distribution. Backends are specified using a URI (Universal Resource Identifier) where the URI scheme is the backend name, e.g., "ipp://11.22.33.44/ipp/print" specifies the "ipp" backend - like PPD files, some backends come with CUPS while others come with your operating system.
Classes are associated with one or more printers and are typically used to distribute print jobs amongst a group of printers or provide redundancy or high availability when printing. Print jobs sent to a class are forwarded to the next available printer in the class.
The lpadmin(8) program is used to add, modify, or delete destinations, while the lpinfo(8) command is used to list the available printer drivers and backends. The cupsctl(8) program is used to manage the printing system as a whole, including things like debug logging and printer sharing. The CUPS web interface ("http://localhost:631" or "https://servername:631") can also be used, and most operating systems provide their own GUI administration tools.

Managing Printers

The lpadmin command is used to create, modify, or delete a printer. The -p option specifies a printer to create or modify:

lpadmin -p printername ...

The lpadmin accepts several additional options after -p printername when adding or modifying a printer:

-D "description"

Sets the description of the printer which is often shown instead of the printer name, for example "HP LaserJet".

-E

Enables the printer and accepts new print jobs.

-L "location"

Sets the location of the printer, for example "Conference Room".

-m model

Sets the printer driver using the model name.

-o option=value

Sets the named option.

-v device-uri

Sets the URI for the printer.

The -x option deletes the named printer:

lpadmin -x printername

Printer Drivers and PPDs

The -m option to lpadmin specifies the driver ("model") to use for the printer. You can run the lpinfo -m command to list all of the available drivers ("models") on your system:

lpinfo -m

Each line contains the driver name followed by its description, for example:

drv:///sample.drv/dymo.ppd Dymo Label Printer
drv:///sample.drv/epson9.ppd Epson 9-Pin Series
drv:///sample.drv/epson24.ppd Epson 24-Pin Series
drv:///sample.drv/generpcl.ppd Generic PCL Laser Printer
drv:///sample.drv/generic.ppd Generic PostScript Printer
drv:///sample.drv/deskjet.ppd HP DeskJet Series
drv:///sample.drv/laserjet.ppd HP LaserJet Series PCL 4/5
drv:///sample.drv/intelbar.ppd Intellitech IntelliBar Label Printer, 2.1
drv:///sample.drv/okidata9.ppd Oki 9-Pin Series
drv:///sample.drv/okidat24.ppd Oki 24-Pin Series
drv:///sample.drv/zebracpl.ppd Zebra CPCL Label Printer
drv:///sample.drv/zebraep1.ppd Zebra EPL1 Label Printer
drv:///sample.drv/zebraep2.ppd Zebra EPL2 Label Printer
drv:///sample.drv/zebra.ppd Zebra ZPL Label Printer
everywhere IPP Everywhere

The everywhere driver is used for nearly all modern networks printers sold since about 2009. For example, the following command creates a destination for a printer at IP address 11.22.33.44:

lpadmin -p printername -E -v ipp://11.22.33.44/ipp/print -m everywhere

The CUPS sample drivers (the "drv:///sample.drv/..." lines above) can be used for "legacy" printers. For example, the following command creates a destination for a HP LaserJet printer at IP address 11.22.33.44:

lpadmin -p printername -E -v socket://11.22.33.44 -m drv:///sample.drv/laserjet.ppd

Note: The CUPS sample drivers are designed to provide basic printing capabilities for the broadest range of printers possible, but generally do not exercise the full potential of the printers or CUPS. Other drivers (including the everywhere driver) provide greater printing capabilities and better print quality.

Device URIs (Backends)

CUPS comes with several standard backends that communicate with printers:

1. dnssd: The Bonjour (DNS-SD) protocol.
2. ipp: The Internet Printing Protocol (IPP) with optional encryption.
3. ipps: The Internet Printing Protocol with mandatory encryption.
4. lpd: The Line Printer Daemon protocol.
5. socket: The AppSocket (JetDirect) protocol.
6. usb: The Universal Serial Bus (USB) printer class.

Run the lpinfo -v command to list the available backends and printers:

lpinfo -v

Each line contains the backend "class" followed by the backend name or a full printer device URI, for example:

network lpd
network ipps
network ipp
network socket
network dnssd://Acme%20Laser%20Pro._ipp._tcp.local./?uuid=545253fb-1cb7-4d8d-98ed-ab6cd607cea7
network dnssd://Bar99._printer.tcp.local./?uuid=f9efff58-9086-4c95-accb-81dee876a475
network dnssd://Example%20EX-42._ipps._tcp.local./?uuid=4a0c67ad-2824-4ddf-9115-7d4226c5fe65
network dnssd://Foo%20Fighter-1969._pdl-datastream._tcp.local./?uuid=4e216bea-c3de-4f65-a710-c99e11c80d2b
direct usb://ZP/LazerJet%20MFP?serial=42

The network class of backends is used for all network protocols. The Using Network Printers help document describes how to use the standard CUPS network backends. The direct class of backends is used for directly-connected printers such as USB and Bluetooth. Because these backends use a system-specific identifier, you should only use the reported device URIs.
Once you know the correct URI for the printer, set it using the lpadmin command's -v option:

lpadmin -p printername -v device-uri

Printer Options

The lpadmin command allows you to set various options for a printer:

-o cupsIPPSupplies=false

Turns off IPP supply level reporting for a printer.

-o cupsSNMPSupplies=false

Turns off SNMP supply level reporting for a printer.

-o name=value

Sets the default value for the named PPD option. For example, -o PageSize=Legal sets the default page size to US Legal.

-o printer-error-policy=name

Sets the policy for errors such as printers that cannot be found or accessed, don't support the format being printed, fail during submission of the print data, or cause one or more filters to crash:

abort-job

Aborts the job on error.

retry-job

Retries the job at a future time.

retry-current-job

Retries the current job immediately.

stop-printer

Stops the printer on error.

-o printer-is-shared=true/false

Enables/disables per-printer sharing. See the section on Printer Sharing for more information.

-o printer-op-policy=name

Sets the operation policy associated with the printer. See the Managing Operation Policies help document for more information.

-u allow:{user|@group}{,user|,@group}*

-u allow:all

-u deny:{user|@group}{,user|,@group}*

-u deny:none

Sets user-level access control for the printer. The allow: list defines a whitelist of users and groups while the deny: list defines a blacklist of users and groups.

Printer Sharing

CUPS supports sharing of printers with other computers and mobile devices. Two cupsctl options control the general printer sharing features:

--share-printers

Enables sharing of printers with other computers and mobile devices on your local network.

--remote-any

Expands printer sharing to any network that can reach your server.

Once you have enabled printer sharing, you then must select which printers will be shared using the lpadmin command and the -o printer-is-shared=true option.
For example, to share two printers ("foo" and "bar") on the local network, run the following commands:

cupsctl --share-printers
lpadmin -p foo -o printer-is-shared=true
lpadmin -p bar -o printer-is-shared=true

Managing Classes

The lpadmin command is used to create, modify, or delete a class. The -c option specifies a class to create or modify and is combined with the -p option:

lpadmin -p printername -c classname

The -r option specifies that the named printer is removed from the class:

lpadmin -p printername -r classname

The -x option deletes the named class:

lpadmin -x classname

Debug Logging and Troubleshooting

The printing system log files track the activity of the scheduler, printer drivers, and backends. If problems occur and the log files do not provide sufficient details to diagnose the problem, you can enable debug logging using the cupsctl command:

cupsctl --debug-logging

To disable debug logging, run the same command with the --no-debug-logging option:

cupsctl --no-debug-logging

How to Setup CUPS Printer Admin Web GUI for Remote Access

How to Setup CUPS Printer Admin Web GUI for Remote Access

There are two ways to manage your printers on Linux environment:

1. First, from command line, using lpadmin command, you can configure your printer and manage the print queues
2. Second, from web UI, you can manage your printers interactively

In one of our previous tutorial, we discussed about how to add new printer, change the printer settings, and manipulate print queues using 12 examples of lpadmin command on Linux.
In this quick tutorial, we’ll show you how you can allow web UI access for an existing CUPS installation.

Manage Printer from Web GUI

All the printer configurations & classes that we setup using lpadmin command line, can also be managed from your browser from the following location:

https://hostname-or-ipaddress:631/admin

To configure this URL, you must do the following changes on your /etc/cups/cupsd.conf
Modify the cupsd.conf file, and do the following two changes:

1. Comment-out this line: Listen localhost:631
2. Add this line Port 631
3. # vi /etc/cups/cupsd.conf .. #Listen localhost:631 Port 631 Listen /var/run/cups/cups.sock ..

Allow Local Subnet to Access Printer Web GUI

Add the local desktop IP address or the subnet from which you want to access the printer URL, it should look like below in /etc/cups/cupsd.conf

# vi /etc/cups/cupsd.conf
..
# Restrict access to the server...
<Location />
  Order allow,deny
  Allow 127.0.0.2
  Allow your-desktop-client-ip-or-subnet
</Location>
..

Note: In the above, change the “your-desktop-client-ip-or-subnet” to the ip-address of your desktop client. Instead of ip-address, you can also specify the subnet here.

Restart the CUPS Service

After making the above changes, restart the CUPS service as shown below.

# service cups restart
Shutting down cupsd    done
Starting cupsd         done

CUPS Web UI for Remote Access

After the above changes, you should be able to access the printer from Web URL as shown below:

https://{your-ip-address}:631/admin

The following displays all the printers that are connected to your Linux system.

Shared Printer Configuration

You can also enable or disable browsing support in your CUPS.
When you enable the browsing, then this will display the shared printers from your local network.
Add the following entries to your cupsd.conf file if you want Browsing to be turned on.

# vi /etc/cups/cupsd.conf
..
Browsing On
BrowseOrder allow,deny
BrowseAllow all
BrowseAddress your-desktop-client-ip-or-subnet
..

Note: Change the your-desktop-client-ip-or-subnet to your ip-address accordingly.
When you turn-off browsing, then polling will be enabled automatically. In this case, you’ll not be able to view all the shared printers from your local network. So, you have to poll for it manually.

# vi /etc/cups/cupsd.conf
..
Browsing Off