Specifications

6-28
Guide to Printers and Printing
Printer Types
The printer–type attribute is defined with the –T printer–type option of the lpadmin
command. A printer type is the generic name for a printer. Typically it is derived from the
manufacturer name. For example, the ACME\ Computer 356 Dot Matrix Printer might have
the type 356. Assigning a type for each printer is important because the print software
extracts information about printers from the terminfo database on the basis of type. This
information includes a list of the printer capabilities that checks the configuration information
you supply to the print service. (By checking the information you provide against the known
capabilities of the type of printer you are configuring, the print service can catch
inappropriate information you may have supplied.) The terminfo database also specifies the
control data needed to initialize a particular printer before printing a file.
While you are not required to specify a printer type, it is good practice to do so. You
enhance your system’s ability to serve your users by classifying, on the basis of type, the
printers available through the print service.
If you give a list of printer types, separate the names with commas. If you do not define a
printer type, the default unknown is used.
You can assign several types to a printer if your printer is capable of emulating more than
one kind of printer. For example, if your printer can emulate an IBM Proprinter XL, an Epson
FX86e, and an HP LaserJet II, the terminfo database names these types 593ibm, 593eps,
and 593hp, respectively. If you specify more than one printer type, the print service uses
one of them, as appropriate, for each print request.
The following example shows how to use the lpadmin command to associate the type
593ibm with the printer named laser.
/usr/sbin/lpadmin –p laser –T 593ibm
Note: If you specify more than one printer type, you must specify simple as the content
type.
Content Types
The content–type attribute is defined with the –I content–type–list option of the lpadmin
command. Most printers can print files of two types: the same type as the printer type (if the
printer type is defined) and the type simple (meaning an ASCII file), which is the default
content type for all printers.
Files of content type simple are assumed to contain only two types of characters, printable
ASCII characters and the following control characters:
backspace Moves the carriage back one space, except at the beginning of a line
tab Moves the carriage to the next tab stop; by default, stops are spaced
every 8 columns on most printers
linefeed Moves the carriage to the beginning of the next line (may require
special port settings for some printers––see Setting Printer Port
Characteristics on page 6-42
form feed Moves the carriage to the beginning of the next page
carriage return Moves the carriage to the beginning of the same line (may fail on
some printers)
The word carriage may be archaic for modern laser printers, but these printers perform
actions similar to those done by a carriage. If a printer can handle several types of files,
including simple, you must include simple explicitly in the content type list. If you do not
want a printer to accept files of type simple, specify a blank content–type–list (–I ””) on
the lpadmin command line. Some printers, though, can accept (and print correctly) several
different types of files. When adding this kind of printer, specify the names of the content
types that the new printer accepts by adding these names to the list. (By default, the list