HP-UX System Administrator's Guide: Overview

Print Destination
The print destination is the printer or printer class where a file containing the print job
will be queued. Several commands for the spooler require you to specify a print
destination. You can appoint one print destination in your spooler to be the system
default printer. Each user can also personalize which printer is their default printer by
setting a shell environment called LPDEST. When LPDEST is defined in a user’s
environment, the printer represented by that variable takes precedence over the system
default printer.
Example 3-3 Default Printer (example)
For example, if the system default printer for a server is defined as laser1 and a user
has defined the environment variable LPDEST with the value ceo_print, then unless
the user specified a print destination their print requests will be sent to the destination
ceo_print. A different user on the same server with no LPDEST environment variable
defined will have their print jobs directed to laser1 unless they specifically identify
a print destination.
Priorities of Printers and Print Requests
In an environment where there is a lot of competition for a given printer or group of
printers, the line printer spooling system offers several ways to prioritize print jobs so
that critical print jobs can effectively “jump to the head of the line”.
Both printers and print requests have priority values associated with them. Typically,
print requests are handled by a printer in the order they are received. By default, print
requests have the printer’s default priority and are printed on a first-in-first-out basis.
However, print jobs can be assigned priority values to raise or lower their priority,
using the -p option of the lp command. Priority values range from 0 to 7, with 7 being
the highest priority. See lp(1) for details.
The priority of a print request can be altered by using the lpalt command. A printer’s
default request priority can be set using the lpadmin command. See lpadmin(1M) and
lpalt(1) for details.
If multiple print requests are waiting to be printed on a specific printer and all have
priorities high enough to print, the printer will print the next print request with the
highest priority. If more than one print request has the same priority, print requests
with that priority will print in the order they were received by the spooler.
Similarly, a priority fence value can be assigned to each printer to set the minimum
priority that a print request must have to print on that printer. A printer’s fence priority
is used to determine which print requests get printed; only requests with priorities
equal to or greater than the printer’s fence priority get printed. The idea is to lower the
fence outside peak usage hours, perhaps via crontab scripts. For more information, see
crontab(1M) and cron(1M). This would allow low priority print jobs submitted during
82 Major Components of HP-UX