AIX offers a third approach toprinting and spooling. It is based on AIX’s general queueing system; printing is just one predefined way to use it. The queueing system’s general operation is illustrated in Figure 13-5.
Figure 13-5. The AIX queueing system
Jobs are submitted to a queue by users using the
commands (or another user command that calls them). A file printed using
these commands is linked to the spooling area by default, so if the file
changes or is deleted before the job actually prints, the output will be
-c option may be used
to copy the file to the spooling area with either command). Print
requests are stored in /var/spool/lpd/qdir, and any spooled files
are stored in /var/spool/qdaemon.
AIX also supports the BSD and System V user print commands for
The queues are monitored by the
qdaemon daemon, which schedules and initiates jobs. When it is
time for a job to execute,
sends the corresponding file to the queue’s backend program for processing. In the case of printing on the
local system, the program is /usr/lib/lpd/piobe, but in theory, any program may be used as a backend (this is discussed further later in this section). The output of the backend program is then sent to a specified physical device in the case of local printing. It may also be ...