Category:LP Spooler

Jump to: navigation, search

The Line Printer Spooling System (LP spooler) is a set of programs, shell scripts, and directories that control your printers and the flow of data going to them.

To understand the LP spooler, think of the LP spooler as a plumbing system. The data to be printed enters the system like "water". Request directories (printer queues) serve as temporary holding tanks for print requests until they are sent to a printer to be printed. The request directory and printer control the flow of print requests. The terms accept and reject refer to controlling the flow of print requests to the request directories, while the terms enable and disable refer to controlling the flow of print requests to the printers. Accepting, rejecting, enabling, and disabling print requests control the data through the LP spooler as valves would control the flow of water in a real plumbing system. Shell scripts (called interface scripts) near the end of the data flow serve as pumps which "pump" an orderly flow of data to the printers.

The line printer scheduler controls the routing of print requests from the request directories to the printers. It functions as an automated flow controller in the "plumbing" system to provide efficient use of the printers. It also prevents intermixed listings (printed pages with characters from different print requests mixed together).

You can also send print requests to another computer to be printed. This is called remote spooling or remote printing. The other computer is referred to as a remote system. When you use remote spooling, a special shell script ("pump") is used to send the data to a remote system (via the rlp command). A program on the remote system, called rlpdaemon, receives the data and directs it into the remote system's LP spooler.