Tips And Tricks I

Configuration

Try to turn off the "job history" of CUPS. So you avoid that CUPS keeps old jobs in the memory. They add up rather quickly on a busy server which, in addition, might not be rebooted for several months.

To do so, put

PreserveJobHistory No

into your '/etc/cups/cupsd.conf' and restart the CUPS daemon with

service cups restart

In 'kupsdconf', that's turning off "Preserve job history" under "Server"/"Misc".

CUPS also stores old jobs on the hard disk in the '/var/spool/cups' directory. To clean it up when the amount of data gets too vast or when there are problems starting the CUPS daemon, enter

service cups stop
rm -f /var/spool/cups/*
rm -f /var/spool/cups/tmp/*
service cups start

Do not delete any directories and do not change the permissions or ownerships of the files and directories.
To delete the files for one printer, do

cancel -a [printer]

article index top

If the CUPS configuration programs ('Kups', 'PrinterDrake', web interface) do not list your USB port and do not auto detect your USB printer, the USB printer port driver probably isn't loaded, This driver is a kernel module called "printer". So type lsmod at the prompt and look whether there is a "printer" entry in the list. If not:

PRINTER=yes

then restart both the USB services and CUPS:

service usb restart
service cups restart

Now the driver should be loaded and the USB port and printer should be visible for the CUPS administration programs.

Note: This driver is only for the USB connection of the printer, you still need to choose a driver for your printer model in the CUPS administration program.

article index top

Printer drivers

Different drivers for one printer

Often there are several drivers for one printer which are written independently by different authors with different intentions. So sometimes there is not simply one driver which provides the best output for all purposes. For text one driver may be best and for photos another. The Linux color ink-jet printing review by the German computer magazine C't (issue 21/2000) came to a similar result . The recommendations of this review are also available on the pages of the appropriate printer models on linuxprinting.org.

If there are several drivers available for your printer, you should try out the different drivers with your typical printing jobs (not only with the CUPS test page) to find the right driver for your needs. If necessary, set up more than one queue for your printer by installing it more than once, each time with another driver. So you can have one queue for text printing and one for photo printing.

Here are some general driver recommendations:

• For color ink-jet printers the best choice is the native CUPS driver of GIMP-Print ("CUPS + GIMP-print v4.0" in printer list entry), which allows an easy step-by-step color calibration for correct color prints.

• A good choice for creative people who want to adjust the individual color intensities in every printout is the GIMP-Print driver of GhostScript ("Foomatic + stp-4.0 (GIMP-Print)" in the printer list entry). It has exactly the same adjustment options as the GIMP plug-in of GIMP-Print: Contrast, Brightness, Saturation, Gamma, Density, Yellow, Magenta, Cyan.

• For PCL laser printers (most non-PostScript lasers) the best choice is the ljet4 driver of GhostScript ("Foomatic + ljet4"). GIMP-Print is optimized for ink-jet printing and the laser printer support is still experimental and has some bugs.

• For PostScript printers you should use the PPD file of the printer's manufacturer, then you get access to all the options of the printer and often a printer understanding both PCL and PostScript reaches its maximum quality and performance only in PostScript.

article index top

If you get PostScript code output on your printer instead of the expected document, you have probably chosen a driver entry for your printer model with a PostScript cartridge. If you have such a cartridge you have to activate it as described in the manual of the cartridge, if not, you have to choose a driver for your printer which supports it in its native language (PCL or anything proprietary). Avoid choosing entries containing "PS", "PostScript", or "Cartridge".

article index top

If your printer model is not listed in the CUPS administration programs of Linux Mandrake at all, then there are several possibilities:

• Your printer is too new to have already been entered in the printer database of linuxprinting.org at the release of Linux Mandrake 7.2. Go to linuxprinting.org, search for your printer and download the appropriate "CUPS-O-Matic PPD file". Copy the file to '/usr/share/cups/model' or one of its subdirectories, restart the CUPS daemon ("service cups restart") and you can install your printer.
  Notice that sometimes additional stuff, as a filter or a new driver to compile into GhostScript is needed. Check the instructions on the web pages.

• Your printer is not supported by free software. In this case the printer is rated "Paperweight" on linuxprinting.org. There might be proprietary software to support it, either supplied by the manufacturer and downloadable for free, or by third parties like ESP Print Pro, Turboprint, or XW Tools. Note that Turboprint and XW Tools do not provide PPD files for CUPS. Of course, you should check whether your printer is supported by the commercial and proprietary solution before you buy.

• Your printer uses some special protocol which needs real-time access or is bi-directional and is therefore inept to be used with a print spooling system like CUPS. Download the driver from the site specified on the printer's page of linuxprinting.org and install it. Use the programs provided with the driver package for printing (Example: Okipage 4w).

• Your printer is not listed on linuxprinting.org but it features an emulation of a known protocol (HP's PCL or Epson's ESC/P 2). Choose an appropriate HP or Epson model.

article index top

Lexmark has started to offer Linux drivers for their color ink-jet printers. There are drivers downloadable for the Z32 and the Z52. They are free of charge, but, unfortunately, they are proprietary software and so they cannot be included in the download editions of Linux distributions and they are not supported by linuxprinting.org. There are no PPD files available for them.

article index top

It is possible to customize the appearance and behavior of a printer by editing its PPD file ('/etc/cups/ppd/[printer].ppd'). For example menu texts can be translated into other languages or options hidden to restrict usage of a printer.
However, broken PPD files can make all printers unaccessible or even prevent the CUPS daemon from running, so be careful and edit PPD files only when you know what you are doing. Also do not remove comment lines with the word "COMDATA" inside. They contain important data which is needed by a filter script to run the printer driver correctly.

article index top