lp(4) — Linux manual page

NAME | SYNOPSIS | CONFIGURATION | DESCRIPTION | FILES | SEE ALSO | COLOPHON

LP(4)                   Linux Programmer's Manual                  LP(4)

NAME         top

       lp - line printer devices

SYNOPSIS         top

       #include <linux/lp.h>

CONFIGURATION         top

       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         top

       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         top

       /dev/lp*

SEE ALSO         top

       chmod(1), chown(1), mknod(1), lpcntl(8), tunelp(8)

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2021-03-22                          LP(4)