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Name
lp — line printer devices
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 root and group lp. You can use printer ports either with
polling or with interrupts. Interrupts are recommended when
high traffic is expected, e.g. for laser printers. For usual
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 only
influences 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 only influences 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:
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.
AUTHORS
The printer driver was originally written by Jim Weigand
and Linus Torvalds. It was further improved by Michael K.
Johnson. The interrupt code was written by Nigel Gamble. Alan
Cox modularised it. LPCAREFUL, LPABORT, LPGETSTATUS were
added by Chris Metcalf.
SEE ALSO
chmod(1), chown(1), mknod(1), lpcntl(8), tunelp(8)
t
Copyright (c) Michael Haardt (michael@cantor.informatik.rwth-aachen.de), Sun Jan 15 19:16:33 1995
This is free documentation; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
The GNU General Public License's references to "object code"
and "executables" are to be interpreted as the output of any
document formatting or typesetting system, including
intermediate and printed output.
This manual is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public
License along with this manual; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
USA.
Modified, Sun Feb 26 15:02:58 1995, faith@cs.unc.edu
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