A system and method for controlling a print job in a printer, such as canceling the print job held in the printer. The system includes a printer having a processor that receives print jobs, including one or more print data swaths, from one or more host computers, and each print data swath includes at least a predefined group of characters. The system also has at least one host computer in communication with the printer and which selectively sends print jobs including print data and/or command data. The host computer further selectively sends a command which is a predetermined group of characters within the print data swath, and the command alters a function in the printer. The command is preferably a series of identical characters, such as NULL characters, and the command preferably causes the printer to enter a command mode to execute the commanded function. The inventive method of controlling print jobs includes the steps of sending a print job having one or more print data swaths from the host computer to the printer, sending a command embedded in a print data swath from the host computer to the printer, and altering a function of the printer with respect to the print job based upon the command received. The method preferably further includes the step of sending a message from the printer to the host computer once the function in the printer has been altered, such as the print job being purged, and to request the host computer to cease sending characters which comprise the command.