Difference between revisions of "CUPS"

Revision as of 02:43, 13 July 2013 (view source) Kynikos (talk | contribs) (Undo revision 265935 by Djszapi (talk) broke sections hierarchy; see also Help:Style#Daemon operations) ← Older edit		Revision as of 02:46, 13 July 2013 (view source) Kynikos (talk | contribs) m (→‎CUPS daemon: clarify for the inattentive user) Newer edit →
Line 174:		Line 174:
	=== CUPS daemon ===		=== CUPS daemon ===
−	With the kernel modules installed, you can now start the '''cups''' and optionally, the '''cups-browsed''' [[daemons]].	+	With the kernel modules installed, you can now start the '''cups''' and optionally, the '''cups-browsed''' [[daemons]], and enable them as required.
	=== Web interface and tool-kit ===		=== Web interface and tool-kit ===

---

Revision as of 02:46, 13 July 2013

zh-CN:CUPS zh-TW:CUPS Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki Template:Article summary wiki Template:Article summary wiki Template:Article summary end

From CUPS' site:

"CUPS is the standards-based, open source printing system developed by Apple Inc. for OS® X and other UNIX®-like operating systems".

Although there are other printing packages such as LPRNG, the Common Unix Printing System is the most popular choice because of its relative ease of use.

CUPS Linux printing workflow

As of cups version 1.5.3-3, Arch Linux makes use of the new full pdf-based printing workflow. For further reading check PDF standard printing job format and an old CUPS filtering chart for history and fun. A good starting point for general Linux printing questions is here.

There are two ways to setup a printer.

• If there's a CUPS server running in your network and sharing a printer you only need to install the client package.
• If the printer is connected directly to your system or you have access to an IPP network printer then setup a local CUPS server.

Installing the client package

The package libcups is the only required package. Install it from the official repositories.

Then add your CUPS server's IP address or hostname into /etc/cups/client.conf. That is all you need. Every application should quickly find the printer(s) shared by that CUPS server.

Optional advanced network setup

It is also possible to run a entire cupsd+cups-browsed instance on your client with Avahi browsing enabled to discover unknown shared printers in your network. This can be useful in large setups where the server is unknown.

Installing CUPS a 32 bit chroot environment

If you have a 64 bit base installation with a 32 bit chroot environment, explicit installation of CUPS is not necessary in the 32 bit environment. To access installed CUPS printers from the chroot environment, one needs to bind the /var/run/cups directory to the same relative location in the chroot environment. Simply create the directory in the chroot (it probably doesn't exist), mount (with -o bind passed to the command}}, and printers should be available from 32 bit chroot applications immediately.

# mkdir /path/to/chroot/var/run/cups
# Example: # mkdir /opt/arch32/var/run/cups

# mount -o bind /var/run/cups /path/to/chroot/var/run/cups

Installing the server packages

The following packages and some printer drivers are needed. Install them from the official repositories.

• cups - the actual CUPS daemon
• cups-filters - essential filters
• ghostscript - (optional) PostScript interpreter
• gsfonts - GhostScript standard Type1 fonts

If you want to enable printer browsing through your network, also install avahi. Make sure avahi-daemon is started before cupsd.

If the system is connected to a networked printer using the Samba protocol or if the system is to be a print server for Windows clients, also install samba.

Printer driver

Here are some of the driver packages. Choosing the right driver depends on the printer:

• gutenprint - A collection of high quality drivers for Canon, Epson, Lexmark, Sony, Olympus, and PCL printers for use with GhostScript, CUPS, Foomatic, and the GIMP
• foomatic-db, foomatic-db-engine, foomatic-db-nonfree, and foomatic-filters - Foomatic is a database-driven system for integrating free software printer drivers with common spoolers under Unix. Installing foomatic-filters should solve problems if the cups error_log is reporting "stopped with status 22!".
• hplip - HP drivers for DeskJet, OfficeJet, Photosmart, Business Inkjet and some LaserJet printer models, as well as a number of Brother printers.
• splix - Samsung drivers for SPL (Samsung Printer Language) printers.

• foo2zjs^AUR - Drivers for ZjStream protocol printers such as the HP Laserjet 1018. More info here. Package is available in the AUR.
• hpoj^AUR - If you are using an HP Officejet, you should also install this package and follow the instructions to avoid problems as in this thread. Package is available in the AUR.
• samsung-unified-driver^AUR - Unified Linux Driver for Samsung printers and scanners. Required for new printers such as the ML-2160. Package is available in the AUR.
• ufr2^AUR or cndrvcups-lb^AUR - Canon UFR2 driver with support for LBP, iR and MF series printers. Package is available in the AUR.

• cups-pdf - A package that allows one to setup a virtual PDF Printer that generates a PDF out of jobs sent to it

If you are not sure of what driver package to install or if the current driver is not working, it may be easiest to just install all of the drivers. Some of the package names are misleading because printers of other makes may rely on them. For example, the Brother HL-2140 needs the hplip driver installed.

Download printer PPD

Depending on the printer, this step is optional and may not be needed, as the standard CUPS installation already comes with quite a few PPD (Postscript Printer Description) files. Moreover, the foomatic-filters, gimp-print and hplip packages already include quite a few PPD files which will automatically be detected by CUPS.

Here is an explanation of what a PPD file is from the Linux Printing website:

"For every PostScript printer the manufacturers provide a PPD file which contains all printer-specific information about the particular printer model: Basic printer capabilities as whether the printer is a color printer, fonts, PostScript level, etc., and especially the user-adjustable options, as paper size, resolution, etc."

If the PPD for the printer is not already in CUPS, then:

• check AUR to see if there are packages for the printer/manufacturer
• visit the OpenPrinting database and select the manufacturer and model of the printer
• visit the manufacturer's site and search for GNU/Linux drivers

Another source for printer drivers

Turboprint is a proprietary driver for many printers not yet supported by GNU/Linux (Canon i*, for example). Unlike CUPS, however, high quality prints are either marked with a watermark or are a pay-only service.

Hardware support and configuration

USB printers

USB printers can get accessed with two methods: The usblp kernel module and libusb. The former is the classic way. It is simple: data is sent to the printer by writing it to a device file as a simple serial data stream. Reading the same device file allows bi-di access, at least for things like reading out ink levels, status, or printer capability information (PJL). It works very well for simple printers, but for multi-function devices (printer/scanner) it is not suitable and manufacturers like HP supply their own backends. Source: here.

Blacklisting usblp

If you have problems getting your USB printer to work, you can try blacklisting the usblp kernel module:

/etc/modprobe.d/blacklistusblp.conf

blacklist usblp

Custom kernel users may need to manually load the usbcore kernel module before proceeding.

Once the modules are installed, plug in the printer and check if the kernel detected it by running the following:

# tail /var/log/messages.log

or

# dmesg

If you're using usblp, the output should indicate that the printer has been detected like so:

Feb 19 20:17:11 kernel: printer.c: usblp0: USB Bidirectional
printer dev 2 if 0 alt 0 proto 2 vid 0x04E8 pid 0x300E
Feb 19 20:17:11 kernel: usb.c: usblp driver claimed interface cfef3920
Feb 19 20:17:11 kernel: printer.c: v0.13: USB Printer Device Class driver

If you blacklisted usblp, you will see something like:

usb 3-2: new full speed USB device using uhci_hcd and address 3
usb 3-2: configuration #1 chosen from 1 choice

Parallel port printers

To use a parallel port printer, you will need to load the lp, parport and parport_pc kernel modules.

Check the setup by running:

# tail /var/log/messages.log

It should display something like this:

lp0: using parport0 (polling).

If you are using a USB to parallel port adapter, CUPS will not be able to detect the printer. As a workaround, add the printer using a different connection type and then change DeviceID in /etc/cups/printers.conf:

DeviceID = parallel:/dev/usb/lp0

HP Printer

HP printers can also be installed via HP's Linux setup tool. Install it by installing hplip from the official repositories.

To run with qt frontend:

# hp-setup -u

To run with command line:

# hp-setup -i

PPD files are in /usr/share/ppd/HP/.

For printers that require the proprietary HP plugin (like the Laserjet Pro P1102w), install the hplip-plugin^AUR package from AUR.

Configuring

Now that CUPS is installed, there are a variety of options on how to set up printing solutions. As always, the tried and true command line method is at your disposal. CUPS also embeds a full-featured web interface. Likewise, various desktop environments such as GNOME and KDE have useful programs that can help manage printers. Depending on your needs, you may choose one method or the other.

If you are planning on connecting to a network printer, rather than one that is directly connected to the computer, you might want to read the CUPS printer sharing page first. Printer sharing between GNU/Linux systems is quite easy and involves very little configuration, whereas sharing between a Windows and GNU/Linux host requires a little bit more effort.

CUPS daemon

With the kernel modules installed, you can now start the cups and optionally, the cups-browsed daemons, and enable them as required.

Web interface and tool-kit

Once the daemon is running, open a browser and go to: http://localhost:631 (The localhost string may need to be replaced with the hostname found in /etc/hostname).

From here, follow the various wizards to add the printer. A usual procedure is to start by clicking on Adding Printers and Classes and then Add Printer. When prompted for a username and password, log in as root. The name assigned to the printer does not matter, the same applies for 'location' and 'description'. Next, a list of devices to select from will be presented. The actual name of the printer shows up next to the label (e.g., next to USB Printer #1 for USB printers). Finally, choose the appropriate drivers and the configuration is complete.

Now test the configuration by pressing the Maintenance drop-down menu then Print Test Page. If it does not print and there is certainty regarding the correctness of applied settings, then the problem is most likely due to missing a proper printer driver.

CUPS administration

A username and password will be required when administering the printer in the web interface, such as: adding or removing printers, stopping print tasks, etc. The default username is the one assigned in the sys group, or root. Other admin groups (e.g. lpadmin or printadmin) may be added to the SystemGroup line in /etc/cups/cups-files.conf (you might have to add this line). See these instructions at cups.org. You might also want to read this post. Create the group[s] (man groupadd) and add the group[s] to users (man usermod). cupsd must be restarted and the user must re-login for these changes to take affect.

If the root account has been locked (i.e. when using sudo), it is not possible to log in the CUPS administration interface with the default username (root) and password. Follow the instructions above to add other users as cups administrators.

Remote access to web interface

By default, the CUPS web interface can only be accessed by the localhost; i.e. the computer that it is installed on. To remotely access the interface, make the following changes to the /etc/cups/cupsd.conf file. Replace the line:

Listen localhost:631

with

Port 631

so that CUPS listens to incoming requests.

Three levels of access can be granted:

<Location />           #access to the server
<Location /admin>	#access to the admin pages
<Location /admin/conf>	#access to configuration files

To give remote hosts access to one of these levels, add an Allow statement to that level's section. An Allow statement can take one or more of the forms listed below:

Allow from all
Allow from host.domain.com
Allow from *.domain.com
Allow from ip-address
Allow from ip-address/netmask

Deny statements can also be used. For example, if wanting to give all hosts on the 192.168.1.0/255.255.255.0 subnet full access, file /etc/cups/cupsd.conf would include this:

# Restrict access to the server...
# By default only localhost connections are possible
<Location />
   Order allow,deny
   Allow from localhost
   Allow from 192.168.1.0/255.255.255.0
</Location>

# Restrict access to the admin pages...
<Location /admin>
   # Encryption disabled by default
   #Encryption Required
   Order allow,deny
   Allow from localhost
   Allow from 192.168.1.0/255.255.255.0
</Location>

# Restrict access to configuration files...
<Location /admin/conf>
   AuthType Basic
   Require user @SYSTEM
   Order allow,deny
   Allow From localhost
   Allow From 192.168.1.0/255.255.255.0
</Location>

You might also need to add:

DefaultEncryption Never

This should avoid the error: 426 - Upgrade Required when using the CUPS web interface from a remote machine.

Command-line configuration

CUPS can be fully controlled from command-line with nice tools, i.e. the lp* and the cups* command families.

On Arch Linux, most commands support auto-completion with common shells. Also note that command-line switches cannot be grouped.

List the devices

# lpinfo -v

List the drivers

# lpinfo -m

Add a new printer

# lpadmin -p printer -E -v device -P ppd

The printer is up to you. The device can be retrieved from the 'lpinfo -i' command. Example:

# lpadmin -p HP_DESKJET_940C -E -v "usb://HP/DESKJET%20940C?serial=CN16E6C364BH"  -P /usr/share/ppd/HP/hp-deskjet_940c.ppd.gz

In the following, the printer references the name you have used here to set up the printer.

Set the default printer

$ lpoptions -d printer

Check the status

$ lpstat -s
$ lpstat -p printer

Deactivate a printer

# cupsdisable printer

Activate a printer

# cupsenable printer

Remove a printer

First set it to reject all incoming entries:

# cupsreject printer

Then disable it.

# cupsdisable printer

Finally remove it.

# lpadmin -x printer

Print a file

$ lpr file
$ lpr -# 17 file              # print the file 17 times
$ echo "Hello, world!" | lpr -p # print the result of a command. The -p switch adds a header.

Check the printing queue

$ lpq
$ lpq -a # on all printers

Clear the printing queue

# lprm   # remove last entry only
# lprm - # remove all entries

Alternative CUPS interfaces

GNOME

If using GNOME, a possibility is to manage and configure the printer by installing system-config-printer.

For system-config-printer to work as it should, running as root may be required, or alternatively set up a "normal" user to administer CUPS (if so follow steps 1-3).

1. Create group, and add a user to it

# groupadd lpadmin
# usermod -aG lpadmin username

2. Add lpadmin to this line in /etc/cups/cups-files.conf

SystemGroup sys root insert here

3. Restart cups, log out and in again (or restart computer)

KDE

KDE users can modify their printers from the Control Center. Both should refer to those desktop environments' documentation for more information on how to use the interfaces.

Other

There is also gtklp^AUR in the AUR.

PDF virtual printer

cups-pdf is a nice package that allows one to setup a virtual printer that will generate a PDF from anything sent to it. This package is not necessary, but it can be quite useful.

After installing the package, set it up as if it were for any other printer by using the web interface. Access the cups print manager: http://localhost:631 and select:

Administration -> Add Printer
Select CUPS-PDF (Virtual PDF), choose for the make and driver:
Make:	Generic
Driver:	Generic CUPS-PDF Printer

Find generated PDF documents in a sub-directory located at /var/spool/cups-pdf. Normally, the subdirectory is named after the user who performed the job. A little tweak helps you to find your printed PDF documents more easily. Edit /etc/cups/cups-pdf.conf by changing the line

#Out /var/spool/cups-pdf/${USER}

to

Out ${HOME}

Print to PostScript

The CUPS-PDF (Virtual PDF Printer) actually creates a PostScript file and then creates the PDF using the ps2pdf utility. To print to PostScript, just print as usual, in the print dialog choose "CUPS-PDF" as the printer, then select the checkbox for "print to file", hit print, enter the filename.ps and click save. This is handy for faxes, etc...

Troubleshooting

The best way to get printing working is to set 'LogLevel' in /etc/cups/cupsd.conf to:

LogLevel debug

And then viewing the output from /var/log/cups/error_log like this:

# tail -n 100 -f /var/log/cups/error_log

The characters at the left of the output stand for:

• D=Debug
• E=Error
• I=Information
• And so on

These files may also prove useful:

• /var/log/cups/page_log - Echoes a new entry each time a print is successful
• /var/log/cups/access_log - Lists all cupsd http1.1 server activity

Of course, it is important to know how CUPS works if wanting to solve related issues:

1. An application sends a .ps file (PostScript, a script language that details how the page will look) to CUPS when 'print' has been selected (this is the case with most programs).
2. CUPS then looks at the printer's PPD file (printer description file) and figures out what filters it needs to use to convert the .ps file to a language that the printer understands (like PJL, PCL), usually GhostScript.
3. GhostScript takes the input and figures out which filters it should use, then applies them and converts the .ps file to a format understood by the printer.
4. Then it is sent to the back-end. For example, if the printer is connected to a USB port, it uses the USB back-end.

Print a document and watch error_log to get a more detailed and correct image of the printing process.

Problems resulting from upgrades

Issues that appeared after CUPS and related program packages underwent a version increment

CUPS stops working

The chances are that a new configuration file is needed for the new version to work properly. Messages such as "404 - page not found" may result from trying to manage CUPS via localhost:631, for example.

To use the new configuration, copy /etc/cups/cupsd.conf.default to /etc/cups/cupsd.conf (backup the old configuration if needed) and restart CUPS to employ the new settings.

All jobs are "stopped"

If all jobs sent to the printer become "stopped", delete the printer and add it again. Using the CUPS web interface, go to Printers > Delete Printer.

To check the printer's settings go to Printers, then Modify Printer. Copy down the information displayed, click 'Modify Printer' to proceed to the next page(s), and so on.

All jobs are "The printer is not responding"

On networked printers, you should check that the name that CUPS uses as its connection URI resolves to the printer's IP via DNS, e.g. If your printer's connection looks like this:

lpd://BRN_020554/BINARY_P1

then the hostname 'BRN_020554' needs to resolve to the printer's IP from the server running CUPS

The PPD version is not compatible with gutenprint

Run:

# /usr/bin/cups-genppdupdate

And restart CUPS (as pointed out in gutenprint's post-install message)

Other

CUPS permission errors

• Some users fixed 'NT_STATUS_ACCESS_DENIED' (Windows clients) errors by using a slightly different syntax:

smb://workgroup/username:password@hostname/printer_name

• Sometimes, the block device has wrong permissions:

# ls /dev/usb/
lp0
# chgrp lp /dev/usb/lp0

HPLIP printer sends "/usr/lib/cups/backend/hp failed" error

Make sure dbus is installed and running. If the error persists, try starting avahi-daemon.

Try adding the printer as a Network Printer using the http:// protocol. Generate the printer URI with hp-makeuri.

HPLIP printer claims job is complete but printer does nothing

This happens on HP printers when you select the (old) hpijs driver (e.g. the Deskjet D1600 series). Instead, use the hpcups driver when adding the printer.

Some HP printers (e.g HP LaserJet) require their firmware to be downloaded from the computer every time the printer is switched on. If there is an issue with udev (or equivalent) and the firmware download rule is never fired, you may experience this issue. As a workaround, you can manually download the firmware to the printer. Ensure the printer is plugged in and switched on, then enter

hp-firmware -n

hp-setup asks to specify the PPD file for the discovered printer

Install CUPS before running hp-setup.

I have installed Qt, but hp-setup reports "Qt/PyQt 4 initialization failed"

"hp-check -t" won't give you useful information to find the required package. You have to install all the "Dependent Packages" prefixed with "python2" in https://www.archlinux.org/packages/extra/x86_64/hplip/

hp-setup finds the printer automatically but reports "Unable to communicate with device" when printing test page immediately afterwards

This at least happens to hplip 3.13.5-2 for HP Officejet 6500A through local network connection. To solve the problem, specify the IP address of the HP printer for hp-setup to locate the printer.

hp-toolbox sends an error, "Unable to communicate with device"

If running hp-toolbox as a regular user results in:

# hp-toolbox
# error: Unable to communicate with device (code=12): hp:/usb/printer id

or, "Unable to communicate with device"", then it may be needed to add the user to the lp and sys groups.

This can also be caused by printers such as the P1102 that provide a virtual cd-rom drive for MS-Windows drivers. The lp dev appears and then disappears. In that case try the usb-modeswitch and usb-modeswitch-data packages, that lets one switch off the "Smart Drive" (udev rules included in said packages).

This can also occur with network attached printers if the avahi-daemon is not running. Another possiblility is the specification of the printer's IP address in hp-setup fails to locate the printer because the IP address of the the printer changed due to DHCP.

CUPS returns '"foomatic-rip" not available/stopped with status 3' with a HP printer

If receiving any of the following error messages in /var/log/cups/error_log while using a HP printer, with jobs appearing to be processed while they all end up not being completed with their status set to 'stopped':

Filter "foomatic-rip" for printer printer_name not available: No such file or director

or:

PID 5771 (/usr/lib/cups/filter/foomatic-rip) stopped with status 3!

make sure hplip has been installed, in addition to the packages mentioned above. See this forum post for more information.

Printing fails with unauthorised error

If the user has been added to the lp group, and allowed to print (set in cupsd.conf), then the problem lies in /etc/cups/printers.conf. This line could be the culprit:

AuthInfoRequired negotiate

Comment it out and restart CUPS.

Print button greyed-out in GNOME print dialogs

Source: I can't print from gnome applications. - Arch Forums

Be sure the package: libgnomeprint is installed

Edit /etc/cups/cupsd.conf and add:

# HostNameLookups Double

Restart cups.service.

Unknown supported format: application/postscript

Comment the lines:

application/octet-stream        application/vnd.cups-raw        0      -

from /etc/cups/mime.convs, and:

application/octet-stream

in /etc/cups/mime.types.

Finding URIs for Windows print servers

Sometimes Windows is a little less than forthcoming about exact device URIs (device locations). If having trouble specifying the correct device location in CUPS, run the following command to list all shares available to a certain windows username:

$ smbtree -U windowsusername

This will list every share available to a certain Windows username on the local area network subnet, as long as Samba is set up and running properly. It should return something like this:

 WORKGROUP
	\\REGULATOR-PC   		
		\\REGULATOR-PC\Z              	
		\\REGULATOR-PC\Public         	
		\\REGULATOR-PC\print$         	Printer Drivers
		\\REGULATOR-PC\G              	
		\\REGULATOR-PC\EPSON Stylus CX8400 Series	EPSON Stylus CX8400 Series

What is needed here is first part of the last line, the resource matching the printer description. So to print to the EPSON Stylus printer, one would enter:

smb://username.password@REGULATOR-PC/EPSON Stylus CX8400 Series

as the URI into CUPS. Notice that whitespaces are allowed in URIs, whereas backslashes get replaced with forward slashes. If it won't work try '%20' instead of spaces.

Print-Job client-error-document-format-not-supported

Try installing the foomatic packages and use a foomatic driver.

/usr/lib/cups/backend/hp failed

Change:

 SystemGroup sys root

to:

 SystemGroup lp root

in /etc/cups/cupsd.conf

Following steps 1-3 in the Alternative CUPS interfaces below may be a better solution, since newer versions of cups will not allow the same group for both normal and admin operation.

Unable to get list of printer drivers

• Check your ServerName in /etc/cups/client.conf is written without http://

ServerName localhost:631

• Try to remove Foomatic drivers.

lp: Error - Scheduler Not Responding

If you get this error when printing a document using:

$ lp document-to-print

Try setting the CUPS_SERVER environment variable:

$ export CUPS_SERVER=localhost

If this solves your problem, make the solution permanent by adding the export line above to ~/.bash_profile.

CUPS prints only an empty and an error-message page on HP LaserJet

There is a bug that causes CUPS to fail when printing images on HP LaserJet (in my case 3380). The bug has been reported and fixed by Ubuntu. The first page is empty, the second page contains the following error message:

 ERROR:
 invalidaccess
 OFFENDING COMMAND:
 filter
 STACK:
 /SubFileDecode
 endstream
 ...

In order to fix the issue, use the following command (as superuser):

 lpadmin -p printer -o pdftops-renderer-default=pdftops

"Using invalid Host" error message

Try to add "ServerAlias *" into cupsd.conf

Printer doesn't print with an "Filter failed" message on CUPS web interface (HP printer)

Change the permissions of the printer USB port:

Get the bus and device number from lsusb, then set the permission using:

chmod 0666 /dev/bus/usb/bus number/device number

To make the persistent permission change that will be triggered automatically each time the computer is rebooted, add the following line.

/etc/udev/rules.d/10-local.rules

SUBSYSTEM=="usb", ATTRS{idVendor}=="Printer_idVendor", ATTRS{idProduct}=="Printer_idProduct", GROUP="lp", MODE:="666"

Obtain the right information by using lsusb command, and don't forget to substitute Printer_idVendor & Printer_idProduct with the relevant ones.

Each system may vary, so consult udev#List_attributes_of_a_device wiki page.

Printer doesn't print with an "Filter failed" message on CUPS web interface (HP printer connected over network)

Start, enable and restart the avahi-daemon.

HPLIP 3.13: Plugin is installed, but HP Device Manager complains it is not

The issue might have to do with the file permission change that had been made to /var/lib/hp/hplip.state. To correct the issue, a simple chmod 644 /var/lib/hp/hplip.state and chmod 755 /var/lib/hp should be sufficient. For further information, please read this link.

Printer is not recognized by CUPS

If your printer is not listed in the "Add Printers" page of the CUPS web interface, nor by lpinfo -v, try the following (suggested in this thread):

• Remove usblp from blacklist
• Load usblp module

modprobe usblp

• Stop cups
• Add the following udev rule in a new rule file:

/etc/udev/rules.d/10-cups_device_link.rules

KERNEL=="lp[0-9]", SYMLINK+="%k", GROUP="lp"

• Reload udev rules:

# udevadm control --reload-rules

• Unplug and re-plug the printer.
• Wait a few seconds and then start cups again.

Can't load /etc/samba/smb.conf

If you're printing to a remote printer over SMB and get this error message: "Can't load /etc/samba/smb.conf - run testparm to debug it", then create an empty smb.conf:

# mkdir /etc/samba
# touch /etc/samba/smb.conf

and restart cupsd.

CUPS' systemd service does not start even though it's enabled

The systemd .service file provided by CUPS uses socket activation, meaning the service is only started when an application connects to CUPS' socket. However, the systemd .socket file provided by cups only works for the local /var/run/cups/cups.sock socket.

In order to have cupsd start when initiating a print job over the network, create the following file:

/etc/systemd/system/cups.socket

.include /usr/lib/systemd/system/cups.socket

[Socket]
ListenStream=0.0.0.0:631
ListenDatagram=0.0.0.0:631
BindIPv6Only=ipv6-only

Then reload systemd:

# systemctl --system daemon-reload

Confirm that everything is working correctly:

# systemctl is-enabled cups.service || systemctl enable cups.service
# systemctl status cups.socket
cups.socket - CUPS Printing Service Sockets
         Loaded: loaded (/etc/systemd/system/cups.socket; enabled)
         Active: inactive (dead)
         Listen: /var/run/cups/cups.sock (Stream)
                 0.0.0.0:631 (Stream)
                 0.0.0.0:631 (Datagram)

CUPS should now start automatically when printing locally or over the network.

See also

• Official CUPS documentation, locally installed
• Official CUPS website
• Linux Printing, The Linux Foundation
• Gentoo's printing guide, Gentoo Documentation resources
• Arch Linux user forums
• Install HP printers easy way