When files are accepted by the lpd server for printing, they are stored in a spool queue directory, together with other files controlling the print operation. This section describes these files and how the LPRng software uses them.
For descriptive purposes, we will use the following printcap entry as a guide:
sd=Spool queue directory name
The :sd option in the printcap entry specifies the spool queue directory. If there is no :sd entry or value, then the printer can only be used by the clients such as lpq to locate the destination for a print job. All information, files, etc., for a print queue is stored in the spool directory.