For the purposes of this example, suppose there is a queue called testqueue, which should be configured so ASCII text is printed with line numbers along the left margin. Apart from that, all files should be printed with two pages scaled to fit on one sheet. The scripts /etc/lpdfilter/testqueue/ascii2ps and /etc/lpdfilter/testqueue/pre, as shown below, would achieve that:

#!/bin/bash
cat -n - | a2ps -1 --stdin=' ' -o -

#!/bin/bash
pstops -q '2:0L@0.6(20cm,2cm)+1L@0.6(20cm,15cm)'

These scripts need to be made executable for all users, which can be achieved with the chmod command:

chmod -v a+rx /etc/lpdfilter/test/ascii2ps
chmod -v a+rx /etc/lpdfilter/test/pre

Reformatting files with pstops only works with PostScript files created to allow such transformations, as is usually the case.

PostScript preloads are small files containing PostScript commands that preceed the print data stream to initialize the printer or the Ghostscript program in the desired way. PostScript preloads are mostly used to enable duplex printing on PostScript printers or to activate a special paper tray. They can also be used for margin and gamma adjustments.

To use preloads, the PostScript printer or Ghostscript must be able to interpret the special commands. Ghostscript, for instance, does not interpret commands related to duplex printing or paper trays.

For this example, the queue testqueue is again used:

To activate one of the above PostScript preloads, create a file similar to /etc/lpdfilter/testqueue/pre:

#!/bin/bash
cat /etc/lpdfilter/testqueue/preload.ps -

In this file, replace preload.ps with the name of your custom preload file. In addition, make this script executable and readable for all users, which can be achieved with chmod in the following way:

chmod -v a+rx /etc/lpdfilter/test/pre 
chmod -v a+r /etc/lpdfilter/test/preload.ps 

Use the mechanism described above to insert PostScript commands not only before the print data, but also after it. For instance, with a script like /etc/lpdfilter/testqueue/pre, reset the printer to its original state after each print job is finished:

#!/bin/bash
cat /etc/lpdfilter/test/preload.ps - /etc/lpdfilter/test/reset.ps

This section provides an example for the customized configuration of a gdi print queue. As explained in Section 5.2.3. “The Issue with GDI Printers”, it is often nearly impossible to make such printers run under Linux. However, special driver programs are available for some GDI models. In most cases, they are designed to run as Ghostscript add-ons with the driver reformatting the Ghostscript output into the printer's own language. Often these drivers make limited use of the printer's functionality, however, allowing only black-and-white printing, for example. If such a driver is available, Ghostscript can be used with it in the following way (also see Section 6.6. “Working with Ghostscript”):

For the steps described below, it is assumed that a GDI printer driver suitable for SUSE LINUX is already installed or can be downloaded from the Internet. It is also assumed that the driver works in the way described above. In some cases, you may need some familiarity with the way source code is handled under Unix or how to handle these installations (from .zip or .tar.gz archives or maybe from .rpm packages).

After unpacking such an archive, you will often find the latest installation instructions included in some of the files, typically in README or INSTALL, or even in a doc subdirectory. If you have downloaded a .tar.gz archive, you usually need to compile and install the driver yourself.

For the purposes of the example explained below, the following setup is assumed:

The Ghostscript driver and the resolution may be different for your printer. Read the documentation included with the driver to find out about these.

First, create the gdi queue. To do so, log in as root and run lprsetup, as follows:

lprsetup -add gdi -lprng -device /dev/lp0 \
  -driver pbmraw -dpi 600 -size a4dj -auto -sf

Now, create the script /etc/lpdfilter/gdi/post:

#!/bin/bash 
/usr/local/bin/printerdriver <gdi_driver_parameters>

Read the documentation of the driver program to find out what options exist for it. Specify them under gdi_driver_parameters as needed. Make the script executable for all users and restart the print spooler:

chmod -v a+rx /etc/lpdfilter/gdi/post 
rclpd stop
rclpd start

From now on, users should be able to print with this command:

lpr -Pgdi <file>