Managing Print Filters

Print filters are programs that convert the content type of a file to a content type that is acceptable to the destination printer. The LP print service uses filters to:

• Convert a file from one data format to another so it can be printed properly on a specific type of printer

• Handle the special modes of printing, like two-sided printing, landscape printing, or draft- and letter-quality printing

• Detect printer faults and notify the LP print service of them so the print service can alert users and system administrators

Not every print filter can perform all these tasks. Because each task is printer-specific, the tasks can be implemented separately.

The LP print service provides the PostScript filters listed in Table 6-1. The filter programs are located in the /usr/lib/lp/postscript directory. For PostScript printing, you usually do not need to do anything beyond installing the filter programs when setting up a print server. Solaris Print Manager automatically enables the supplied filters. However, if you administer other printers, you might need to administer print filters for them.

Creating Print Filters

To create a new print filter, you must write a print filter program and create a print filter definition. Filters contain input types, output types, and complex options that provide a language to process command-line arguments within the filter. See "Creating a New Print Filter" for background information and step-by-step instructions.

Adding, Changing, Removing, and Restoring Print Filters

Print filters are added, changed, or removed on the print server only.

You use the lpfilter(1M) command to manage the list of available filters. System information about filters is stored in the /etc/lp/filter.table file. The lpfilter command gets the information about filters to write to the table from filter descriptor files. The filter descriptor files supplied (PostScript only) are located in the /etc/lp/fd directory. The actual filter programs are located under /usr/lib/lp.

The LP print service imposes no fixed limit on the number of print filters you can define. You can remove filters that are no longer used to avoid extra processing by the LP print service. (LP examines all filters to find one that works for a specific print request.) If in doubt, do not remove a filter.

As you add, change, or delete filters, you can overwrite or remove some of the original filters provided by the LP print service. You can restore the original set of filters, if necessary, and remove any filters you have added.

SunOS software provides a default set of PostScript filters, which Solaris Print Manager automatically adds to a print server. Some of the TranScript filters used with SunOS 4.1 have SunOS equivalents, but others do not. The table below lists the default PostScript filters and identifies the TranScript filters, where applicable.

The SunOS software does not provide the following filters:

• TEX

• oscat (NeWSprint opost)

• Enscript

The postreverse, postprint, postio, and dpost filters are provided in place of Enscript.

Solaris Print Manager adds the default PostScript filters to a print server. If you have printing needs that are not met by these filters, see "How to Create a New Print Filter" for information about writing a custom print filter.

How to Add a Print Filter

1. Log in as superuser or lp on the print server.

2. Add a print filter that is based on a print filter definition by using the lpfilter command.

   # lpfilter -f filter-name -F filter-def

   -f filter-name	Name you choose for the print filter.
   -F filter-def	Name of the print filter definition.

   The print filter is added in the print server's /etc/lp/filter.table file.

3. Verify that the print filter was added by checking for information about the print filter in the output of the following command.

   # lpfilter -f filter-name -l

Example--Adding a Print Filter

In the following example, the command adds the daisytroff print filter that has the daisytroff.fd print filter definition.

# lpfilter -f daisytroff -F /etc/lp/fd/daisytroff.fd

How to Delete a Print Filter

1. Log in as superuser or lp on the print server.

2. Delete the print filter by using the lpfilter command.

   # lpfilter -f filter-name -x

   -f filter-name	Name of the print filter to be deleted.
   -x	Deletes the specified filter.

   The print filter is deleted from the print server's /etc/lp/filter.table file.

3. Verify that filter was deleted by using the following command. You should receive an error indicating that no filter by the specified name exists.

   # lpfilter -f filter-name -l

Example--Deleting a Print Filter

In the following example, the command deletes the daisytroff print filter.

# lpfilter -f daisytroff -x

How to View Information About a Print Filter

1. Log in as superuser or lp on the print server.

2. Request information about a print filter by using the lpfilter command.

   # lpfilter -f filter-name -l

   -f filter-name	Print filter for which you want to view information. Specify all for filter-name to view information about all the available print filters.
   -l	Displays information about the specified filter.

   Information about the specified print filter(s) is displayed.

Examples--Viewing Information About a Print Filter

In the following example, the command requests information for the postdaisy print filter, and the information that is displayed in response.

# lpfilter -f postdaisy -l
Input types: daisy
Output types: postscript
Printer types: any
Printers: any
Filter type: slow
Command: /usr/lib/lp/postscript/postdaisy
Options: PAGES * = -o*
Options: COPIES * = -c*
Options: MODES group = -n2
Options: MODES group\=\([2-9]\) = -n\1
Options: MODES portrait = -pp
Options: MODES landscape = -pl
Options: MODES x\=\(\-*[\.0-9]*\) = -x\1
Options: MODES y\=\(\-*[\.0-9]*\) = -y\1
Options: MODES magnify\=\([\.0-9]*\) = -m\1

In the following example, the command redirects information about the daisytroff filter to a file (creates the filter definition for that filter). This is useful if a filter definition is removed unintentionally.

# lpfilter -f daisytroff -l > daisytroff.fd

In the following example, the command displays all the print filters that have been added to the system, and the information that is displayed in response.

# lpfilter -f all -l | grep Filter
(Filter "download")
Filter type: fast
(Filter "postio")
Filter type: fast
(Filter "postior")
Filter type: fast
(Filter "postreverse")
Filter type: slow