Lp0 on fire - Citizendia

lp0 on fire (aka Printer on Fire) is a semi-obsolete error message still generated on some Unix/Linux operating systems in response to certain types of printer errors. lp0 is the Unix device handle for the first line printer, but the error can be displayed for any printer attached to a Unix/Linux system. The lp command is used on many Unix-like systems to assign jobs to printer queues The line printer is a form of high speed impact printer in which one line of type is printed at a time

The origin of the "on fire" message was in the 1970's when line printers were large mechanical affairs with a high speed drum rotating at 1200 to 2400 RPM and impact printing heads. The line printer is a form of high speed impact printer in which one line of type is printed at a time Misaligned operating components could cause the paper to come into direct contact with the high speed rotating parts, generating quite a bit of paper dust and increasing the likelihood of a paper jam. If a jam were not detected soon enough, the accumulated paper dust, ink dust and paper could generate enough friction along the rotating drum to start a fire. Friction is the Force resisting the relative motion of two Surfaces in contact or a surface in contact with a fluid (e Furthermore, the cleaning solutions used in the printers were usually alcohol based, the fumes of which also presented a fire hazard. In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon However, it must be noted that there have never been any actual reports of printers which had friction related fires.

The line printer employed a series of status codes, specifically ready, online, and check. If the online status were set to "off" and the check status were set to "on," the operating system would interpret this as the printer running out of paper. However, if the online code were set to "on" along with the check code also set to "on" this would mean that the printer still has paper, but is suffering an error, and is still running. Due to the hazardous conditions which could arise in early line printers, Unix displayed the message "on fire", which would serve to motivate any system operator viewing the message to go and check on the line printer immediately. ^[1]

While modern inkjet and laser printers are nowhere near as flammable as their mainframe ancestors, the lp device code in all sorts of POSIX compliant operating systems retained this legacy message. Inkjet printers operate by propelling variably-sized droplets of liquid or molten material ( Ink) onto almost any sized page A laser printer is a common type of Computer printer that rapidly produces high quality text and graphics on plain paper The lp command is used on many Unix-like systems to assign jobs to printer queues POSIX (ˈpɒzɪks or "Portable Operating System Interface" is the collective name of a family of related standards specified by the IEEE to define Legacy code is Source code that relates to a no-longer supported or manufactured Operating system or other Computer technology As printer drivers and support improved this error condition could be trapped and handled appropriately, and as a result, most Unix/Linux users today have never encountered the "on fire" message. However, the message is still present in many kernels, especially with legacy parallel port device support, and continues to baffle users to this day. A parallel port is a type of interface found on Computers ( personal and otherwise for connecting various peripherals ^[2]

The "on fire" message is also present in other components, often to a humorous effect. For example, in some kernels' CPU code, a CPU thermal failure could result in the message "CPU#0: Possible thermal failure (CPU on fire ?). " ^[3]

References

^ Mailing list post relating the history of the lp0 on fire error. Retrieved on 2007-09-11. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 9 - The Battle of the Teutoburg Forest ends 506 - The Bishops of Visigothic Gaul
^ Help, my printer port is on fire!!!. Retrieved on 2007-09-11. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 9 - The Battle of the Teutoburg Forest ends 506 - The Bishops of Visigothic Gaul
^ CPU#0: Possible thermal failure (CPU on fire ?). Retrieved on 2008-05-27. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 927 - Simeon the Great, Tsar of Bulgaria, dies 1120 - Richard III of Capua is anointed

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