Managing Print Filters

Managing Print Filters
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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 complete the following tasks:

Convert a file from one data format to another format so that it can be printed properly on a specific type of printer
Handle the special modes of printing, such as two-sided printing, landscape printing, draft-quality, and letter-quality printing
Detect printer faults and notify the LP print service, so that 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 5–1. The filter programs are located in the /usr/lib/lp/postscript directory. For PostScript printing, you usually only need to install 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. For more information and step-by-step instructions, see Creating a New Print Filter.

Adding, Changing, Deleting, and Restoring Print Filters

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

You can use the lpfilter 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 that are supplied (PostScript only) are located in the /etc/lp/fd directory. The actual filter programs are located in the /usr/lib/lp directory.

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 a filter 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. You can also remove any filters you have added.

SunOS software provides a default set of PostScript filters. Solaris Print Manager automatically adds these filters to a print server. Some of the TranScript filters used with lpd-based print services have SunOS equivalents, but other TranScript filters do not. The following table lists the default PostScript filters and identifies the equivalent TranScript filters, where applicable.

Table 5.1. Default PostScript Filters

PostScript Filter	Action	TranScript Equivalent
`download`	Used to download fonts
`dpost`	Changes `ditroff` to PostScript	`psdit`
`postdaisy`	Changes `daisy` to PostScript
`postdmd`	Changes `dmd` to PostScript
`postio`	Used for serial interface for PostScript printer	`pscomm`
`postior`	Used to communicate with printer
`postmd`	Changes matrix gray scales to PostScript
`postplot`	Changes `plot` to PostScript	`psplot`
`postprint`	Changes `simple` to PostScript	`enscript`
`postreverse`	Used to reverse or select pages	`psrev`
`posttek`	Changes `TEK4014` to PostScript	`ps4014`

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. This section provides information about writing a custom print filter.

How to Add a Print Filter

Log in as superuser, lp, or assume an equivalent role on the print server.
Add a print filter that is based on a print filter definition.
```
# lpfilter -f filter-name -F filter-definition
```
f filter-name

Specifies the name you choose for the print filter.

F filter-definition

Specifies the name of the print filter definition.

For more information, see the lpfilter ( 1M ) man page.

The print filter is added in the print server's /etc/lp/filter.table file.
Verify that the print filter was added.
```
# lpfilter -f filter-name -l
```

Example 5.7. Adding a Print Filter

The following example shows how to add 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

Log in as superuser, lp, or assume an equivalent role on the print server.
Delete the print filter.
```
# lpfilter -f filter-name -x
```
f , filter-name

Specifies the 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.
Verify that the filter was deleted.
```
# lpfilter -f filter-name -l
```
You should receive an error indicating that no filter by the specified name exists.

Example 5.8. Deleting a Print Filter

The following example shows how to delete the daisytroff print filter.

# lpfilter -f daisytroff -x

How to View Information About a Print Filter

Log in as superuser, lp, or assume an equivalent role on the print server.
Request information about a print filter.
```
# lpfilter -f filter-name -l
```
f

Specifies the print filter for which you want to view information. Specify all for filter-name to view information about all available print filters.

l

Displays information about the specified filter.

Information about the specified print filter or filters is displayed.

Example 5.9. Viewing Information About a Print Filter

This example shows how to request information for the postdaisy print filter. Sample command output follows.

# 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

Example 5.10. Viewing Information About All Print Filters on a System

This example shows how to display all the print filters that have been added to the system. Sample command output follows.

# 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

Example 5.11. Redirecting Information About a Print Filter

This example shows how to redirect information about the daisytroff filter to a file. This task is useful if a filter definition is removed unintentionally.

# lpfilter -f daisytroff -l > daisytroff.fd

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