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AIX Version 4.3 Guide to Printers and Printing

Spooler Parts

The AIX spooler can be viewed as a process or a subsystem with a beginning, points-in-between, and an ending. To accomplish its tasks, the AIX spooler has four basic parts:

  1. The enq command is the true entry point to the spooler, and as such is the beginning of any spooler activity. This command accepts requests for job processing.
  2. The qdaemon is responsible for accepting and tracking all jobs submitted to the spooler by the enq command. It is also responsible, once all the necessary resources are available, for allowing a queue backend to process a job. The qdaemon is one of the points-in-between in the spooler process.
  3. The spooler backend is a collection of programs invoked by the spooler's qdaemon command to process a job in some queue. The backend sends output to a specific device, such as a printer. When the backend is piobe, it involves a formatter filter, which in turn involves a printer colon file. The backend is one of the points-in-between as well as the ending, since the backend contains the specific process that will deliver the processed job to its final destination.
  4. The configuration file, /etc/qconfig, describes the configuration of available queues and devices. Both the enq command and the qdaemon command refer to the configuration file. This configuration file is considered as conceptually important as the other three spooler parts due to its critical value to the correct operation of the AIX spooler as a whole.

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