# lp

## NAME



           lp - line printer devices
    


## SYNOPSIS



           **#include <linux/lp.h>**
    


## CONFIGURATION



           **lp**[0–2] are character devices for the parallel line printers; they
           have major number 6 and minor number 0–2.  The minor numbers
           correspond to the printer port base addresses 0x03bc, 0x0378, and
           0x0278.  Usually they have mode 220 and are owned by user _root_ and
           group _lp_.  You can use printer ports either with polling or with
           interrupts.  Interrupts are recommended when high traffic is
           expected, for example, for laser printers.  For typical dot matrix
           printers, polling will usually be enough.  The default is polling.
    


## DESCRIPTION



           The following ioctl(2) calls are supported:
    
           **int ioctl(int** fd**, LPTIME, int** arg**)**
                  Sets the amount of time that the driver sleeps before
                  rechecking the printer when the printer's buffer appears to
                  be filled to _arg_.  If you have a fast printer, decrease
                  this number; if you have a slow printer, then increase it.
                  This is in hundredths of a second, the default 2 being 0.02
                  seconds.  It influences only the polling driver.
    
           **int ioctl(int** fd**, LPCHAR, int** arg**)**
                  Sets the maximum number of busy-wait iterations which the
                  polling driver does while waiting for the printer to get
                  ready for receiving a character to _arg_.  If printing is too
                  slow, increase this number; if the system gets too slow,
                  decrease this number.  The default is 1000.  It influences
                  only the polling driver.
    
           **int ioctl(int** fd**, LPABORT, int** arg**)**
                  If _arg_ is 0, the printer driver will retry on errors,
                  otherwise it will abort.  The default is 0.
    
           **int ioctl(int** fd**, LPABORTOPEN, int** arg**)**
                  If _arg_ is 0, open(2) will be aborted on error, otherwise
                  error will be ignored.  The default is to ignore it.
    
           **int ioctl(int** fd**, LPCAREFUL, int** arg**)**
                  If _arg_ is 0, then the out-of-paper, offline, and error
                  signals are required to be false on all writes, otherwise
                  they are ignored.  The default is to ignore them.
    
           **int ioctl(int** fd**, LPWAIT, int** arg**)**
                  Sets the number of busy waiting iterations to wait before
                  strobing the printer to accept a just-written character,
                  and the number of iterations to wait before turning the
                  strobe off again, to _arg_.  The specification says this time
                  should be 0.5 microseconds, but experience has shown the
                  delay caused by the code is already enough.  For that
                  reason, the default value is 0.  This is used for both the
                  polling and the interrupt driver.
    
           **int ioctl(int** fd**, LPSETIRQ, int** arg**)**
                  This ioctl(2) requires superuser privileges.  It takes an
                  _int_ containing the new IRQ as argument.  As a side effect,
                  the printer will be reset.  When _arg_ is 0, the polling
                  driver will be used, which is also default.
    
           **int ioctl(int** fd**, LPGETIRQ, int *** arg**)**
                  Stores the currently used IRQ in _arg_.
    
           **int ioctl(int** fd**, LPGETSTATUS, int *** arg**)**
                  Stores the value of the status port in _arg_.  The bits have
                  the following meaning:
                  LP_PBUSY     inverted busy input, active high
                  LP_PACK      unchanged acknowledge input, active low
                  LP_POUTPA    unchanged out-of-paper input, active high
                  LP_PSELECD   unchanged selected input, active high
                  LP_PERRORP   unchanged error input, active low
    
                  Refer to your printer manual for the meaning of the
                  signals.  Note that undocumented bits may also be set,
                  depending on your printer.
    
           **int ioctl(int** fd**, LPRESET)**
                  Resets the printer.  No argument is used.
    


## FILES



           _/dev/lp*_
    


* * *