User`s guide

2-5
Printers, Print Jobs, and Queues for Systems Administrators
The formatter filter is made up of two components:
• A device–independent formatter driver
• A device–dependent formatter
The formatter driver is invoked by a pipeline and is passed the name of a formatter to be
driven. The formatter driver dynamically loads and links the formatter and calls the
formatter’s setup function which indicates whether data formatting or data pass–through is
requested. After the formatter’s setup function performs the necessary functions, it returns
to the formatter driver. The formatter driver calls the initialize function. The initialize
function outputs a string of printer commands to initialize the printer and returns to the
formatter driver.
The formatter driver either calls the passthru function once or calls the lineout function for
each line in the print file based on the return code from the setup function. If the lineout
function is called, the formatter driver performs all vertical spacing, including line spacing,
vertical tabs, form feeds, and top and bottom margins. Line spacing and vertical tabs are
performed by the lineout function. Other vertical spacing functions are performed
automatically.
When processing is complete, the formatter driver calls the restore function. The restore
function outputs a string of printer commands to restore the printer to its default state,
defined by the database attribute values.
For more information about how the print formatter interacts with the printer formatter
subroutines, refer to the example of a print formatter, on page 4-25.
Printer Terminology
Printer/Plotter
Device
A special file in the /dev directory for the device. This file can be used
by redirection (for example, cat FileName > /dev/lp0). Settings
for the device driver can be displayed and changed using the Devices
fastpath or the lsdev and chdev commands. Before printer commands
can access a printer device, a print queue must be created for the
device or the printer must be configured in the printer backend in
/etc/qconfig.
Virtual Printer A combination of a specific queue and a specific queue device in the
/etc/qconfig file. There is an associated file in the
/var/spool/lpd/pio/@local/ddi directory that contains formatting data.
When you use SMIT to add a printer, the system automatically creates
the virtual printer’s queue, queue device, and
/var/spool/lpd/pio/@local/ddi file.
Use the Devices fastpath to create a queue and queue device for a
printer, using the standard piobe backend. If you want to implement
load sharing, use to add a second queue device to an existing queue.
You can also use the SMIT commands.
Queue A line or list of items in the /etc/qconfig file where the name of the
queue manually points to the associated queue device. The following is
a sample listing:
lp0: device = lp0
Normally, queues are created through Web-based System Manager.