Specifications

6-22
Guide to Printers and Printing
• Names of specific printers to which it will send jobs
• Type of the filter (whether it is a fast filter or a slow filter)
• Options
See Adding a Filter to the Print Service on page 6-27 for more information.
Filter definitions, which can be stored in a file or entered directly on the command line, have
the following format:
Command: command–pathname [ options ]
Input types: input–type–list
Output types: output–type–list
Printer types: printer–type–list
Printers: printer–list
Filter type: fast or slow
Options: template–list
The information can appear in any order. Not all the information must be provided. When
you do not specify values for the items listed below, default values are assigned.
lpfilter Arguments Default
Command: (no default)
Input types: any
Output types: any
Printer types: any
Printers: any
Filter type: slow
Options: (no default)
Default values define a flexible filter, so at minimum you must supply the input and output
type(s). When you enter a list, you can separate the items in it with blanks or commas,
unless it is a template–list. Items in a template–list must be separated by commas.
Each of these characteristics is described as follows:
• Command: The full path of the filter program.
If there are any fixed options that the program always needs, include them here.
• Input types: The list of file content types that the filter can process.
The print service does not impose a limit on the number of input types that can be
accepted by a filter, but most filters can take only one. Several file types may be similar
enough so that the filter can handle them. You can use any name having a maximum of
14 alphanumeric characters and dashes (not underscores). Because the print service
uses these names to match a filter with a file type, follow a consistent naming
convention. For example, if more than one filter can accept the same input type, use the
same name for that input type when you specify it for each filter. Advise your users of the
names so they know how to identify the type of a file when submitting that file for
printing.
• Output types: The list of file types that the filter can produce as output.
For each input type, the filter produces a single output type. The output type may vary,
however, from job to job. The names of the output types are restricted to 14
alphanumeric characters and dashes.
These names should either match the types of printers you have on your system or
match the input types handled by other filters. The print service groups filters together in
a shell pipeline if it finds that several passes by different filters are needed to convert a