Spool Files/Print files

Spool files exist to hold information that is on its way somewhere else--to your printer, for example. On the instructions of a program or a command that you might use, the computer creates spool files. They are the computer's equivalent of in-boxes and out-boxes.

In-box spool files are called input spool files. Out-box spool files are called output spool files. HP Easytime/iX refers to certain kinds of output spool files as print files. Print files are one kind of output spool file (files destined for printing).

The reason for creating spool files is that your computer cannot do everything all at once, fast as it is.

Your printer, for example, can print only one file at a time. More precisely, it can print only one character, or one line, or perhaps one page, at a time. While one line of your report is printing, all of the remaining lines in the report must wait. Every other file destined for printing must wait, too.




	Worth Knowing: Spool files (input and output) are involved in many of the processes that the computer uses, not just in printing.

To avoid wasting time waiting for the printer, the computer creates spool files. The computer fills up an in-box or an out-box, then waits for an instruction to use the contents. When the opportunity to act arises, the computer processes its spool file(s) and moves on to the next task. Once it has finished using a spool file, the computer (usually) erases the spool file.

The inability of printers (and other devices such as tape drives) to handle more than one thing at a time makes them nonshareable devices. You and every other user on your system do share the services of the printer. But files destined for the printer (or some other processing) must often wait their turn.

The computer keeps track of all of the files destined for printing (or some other process). It records the day and time of day when they were sent for printing. It notes their size and their priority in the waiting line, called a queue. It prints first those files of highest priority and prints them in the order that they were sent to the printer. It next prints files of lower priorities, again, printing them in their order of receipt.

Output spool files

The print file of a letter you write--an output spool file destined for the printer--may contain more than the original contents of the letter that you wrote and sent to the printer. This out-box spool file may contain formatting and printing instructions that turn the file into the finished, presentable letter that you had in mind. The instructions are added by the process that actually sends the file to the printer (frequently the program that you used to create your letter).

These out-box files are stored on the disk. They have unusual names, such as #O3488675, which signify, first that they are output (out-box) files--that is the "O" part of the name. The digits following "O" form a code that signify their order of creation.




	TIP: You may use the `LISTSPF` command to find the names of any output (and input) spool files that are connected with your session. Consult the `LISTSPF` command in the book, Commands Reference (B3813-90011) to learn how to identify the output spool file (print file) that is associated with your user name and account.

When its turn arrives, each output spool file destined for printing (a print file) goes to the printer. When the printing is finished, the computer usually erases the temporary output spool file (print file).




	TIP: An output spool file (print file) can be made permanent. Why would you do that? You might want to examine the file to be sure that it is, indeed, what you intended for the printer. You may wish to change its priority in the waiting line (the queue). The `SPOOLF` command allows you to make spool files permanent or to change their priority in the queue.

Once you have identified the output spool file created for your text file, you can do this, for example:

   SPOOLF  #O3488675;PRI=9

This will raise the output priority of the spool file #O3488675 to 9.

A print file is one form of output spool file--a file destined for the printer. There are other output spool files destined for other nonshareable devices (or awaiting processing of some kind), but these are not called print files. They are simply output spool files.




	TIP: It is tempting to give your output spool file the highest possible priority and race to the head of the line. Some work does truly deserve higher priority--but only some.

Input spool files

There are also input spool files. These, too, are waiting their turn, not for printing, but usually for processing of one sort or another. They are designated with names such as #I3499852--the "I" is for input.

As a generalization, input spool files contain instructions for the processing of information rather than the result of processing. Output spool files usually contain the result of some processing.

Unless you become extremely sophisticated in your use of the computer, input spool files will remain out of your reach, and you will have little reason to be aware of them. You cannot examine or modify them. You can, however, find their names with the LISTSPF command.

Because the computer can process input spool files much more quickly than a printer can print output spool files, it is not uncommon for the input spool files created as part of your work to be processed and erased before you have a chance to find them.

Spool Files/Print files

Technical documentation

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Output spool files

Input spool files