Typical user commands available to the System V printing system are: In the Unix programming model, device files are special files that act as access points to peripheral devices such as printers.
Such a system, with an lp command to send documents to the queue, was first introduced in 1973 in Version 4 of Unix.
[4] With its distribution in the influential AT&T Unix System V, the interface if not the implementation became the standard for users' control over printers.
"[9] By 2003, a survey of the Debian, Mandrake, Red Hat, Slackware and SuSE distributions showed that all of them were running some combination of lpr, LPRng and CUPS.
As a result, Gray observed that "many administrators choose to simply run the old lpr/lpd system on the SVR4 boxes.