Specifications

3-17
Spooler Overview
Following the tab–indented lines, the qdaemon must find the word that is the value of the
device parameter followed by a colon; this line represents the beginning of the device
stanza. This word, which a user normally does not need to know, is the name of a device to
which the corresponding queue stanza provides serial access. There must be one or more
lines indented by tabs following this line. One of these lines must be backend =
full_path_name_to_backend. In a local spooling environment, there are two parameters of
critical importance in this stanza.
The file parameter specifies the real device to which the queue provides serial access. It is
important to note that jobs submitted to the spooling system are queued upon this device. If
a queue is setup to use a printer known to the operating system as lp1, then the value of
the file parameter would be /dev/lp1. The operating system routines that create queues use
the name of the real device as the name of the device stanza by default, and this is why
there is some confusion as to the meaning of the device parameter.
The backend parameter specifies the full path to the program that will process the job
submitted to the spooling system, after the qdaemon determines that the job’s turn to be
processed has arrived.
Spooler Queues, Virtual Printers, and Physical Printers
The Four Queues – Four Virtual Printers – One Physical Printer example depicts an
instance of /etc/qconfig that defines four queues on a single physical printer, in this case
/dev/lp1. Notice that all four pairs of stanzas use the string lp1 to connect a queue stanza
to a device stanza. It is the file parameter in each device stanza that specifies that the
printer known to the base operating system as lp1, and whose device driver entry point is
/dev/lp1, is the actual physical destination of any jobs submitted to any of these queues.
When these queues were defined with SMIT, the command that actually creates the queue
definition needed a string to connect the two halves of each stanza pair. Because the
physical printer at hand was lp1, the string lp1 was used as the both the value of the
device parameter in each queue stanza and as the name of each device stanza. This
format is detailed in the /etc/qconfig File Structure examples below.
asc:
device = lp1
lp1:
file = /dev/lp1
header = never
trailer = never
access = both
backend = /usr/lib/lpd/piobe
gl:
device = lp1
lp1:
file = /dev/lp1
header = never
trailer = never
access = both
backend = /usr/lib/lpd/piobe
pcl:
device = lp1
lp1:
file = /dev/lp1
header = never
trailer = never
access = both
backend = /usr/lib/lpd/piobe