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Linux 2.6 - man page for tunelp (linux section 8)

tunelp(8)			    Linux Programmer's Manual				tunelp(8)

NAME
       tunelp - set various parameters for the lp device

SYNOPSIS
       tunelp  device  [-i  IRQ]  [-t  TIME] [-c CHARS] [-w WAIT] [-a {on|off}] [-o {on|off}] [-C
       {on|off}] [-r] [-s] [-q {on|off}] [-T {on|off}]

DESCRIPTION
       tunelp sets several parameters for the /dev/lp? devices, for better  performance  (or  for
       any  performance at all, if your printer won't work without it...)  Without parameters, it
       tells whether the device is using interrupts, and if so, which one.  With  parameters,  it
       sets the device characteristics accordingly.  The parameters are as follows:

       -i IRQ specifies  the  IRQ  to  use  for the parallel port in question.	If this is set to
	      something non-zero, -t and -c have no effect.  If your port  does  not  use  inter-
	      rupts,  this option will make printing stop.  The command tunelp -i 0 restores non-
	      interrupt driven (polling) action, and your printer should  work	again.	 If  your
	      parallel port does support interrupts, interrupt-driven printing should be somewhat
	      faster and efficient, and will probably be desirable.

	      NOTE: This option will have no effect with kernel 2.1.131 or later since the irq is
	      handled  by  the	parport  driver.  You  can change the parport irq for example via
	      /proc/parport/*/irq.   Read   /usr/src/linux/Documentation/parport.txt   for   more
	      details on parport.

       -t TIME
	      is  the amount of time in jiffies that the driver waits if the printer doesn't take
	      a character for the number of tries dictated  by	the  -c  parameter.   10  is  the
	      default  value.  If you want fastest possible printing, and don't care about system
	      load, you may set this to 0.  If you don't care how fast your printer goes, or  are
	      printing text on a slow printer with a buffer, then 500 (5 seconds) should be fine,
	      and will give you very low system load.  This value generally should be  lower  for
	      printing graphics than text, by a factor of approximately 10, for best performance.

       -c CHARS
	      is  the number of times to try to output a character to the printer before sleeping
	      for -t TIME.  It is the number of times around a loop that tries to send a  charac-
	      ter  to  the  printer.  120 appears to be a good value for most printers in polling
	      mode.  1000 is the default, because there are some printers that become jerky  oth-
	      erwise,  but  you  must set this to `1' to handle the maximal CPU efficiency if you
	      are using interrupts. If you have a very fast printer, a value  of  10  might  make
	      more  sense  even  if  in  polling mode.	If you have a really old printer, you can
	      increase this further.

	      Setting -t TIME to 0 is equivalent to setting -c CHARS to infinity.

       -w WAIT
	      is the number of usec we wait while playing with the  strobe  signal.   While  most
	      printers	appear	to  be able to deal with an extremely short strobe, some printers
	      demand a longer one.  Increasing this from the default 1 may make  it  possible  to
	      print  with  those  printers.  This may also make it possible to use longer cables.
	      It's also possible to decrease this value to 0 if your printer is  fast  enough  or
	      your machine is slow enough.

       -a {on|off}
	      This is whether to abort on printer error - the default is not to.  If you are sit-
	      ting at your computer, you probably want to be able to see an error and fix it, and
	      have  the  printer  go  on  printing.   On the other hand, if you aren't, you might
	      rather that your printer spooler find out that the printer isn't ready,  quit  try-
	      ing, and send you mail about it.	The choice is yours.

       -o {on|off}
	      This  option is much like -a.  It makes any open() of this device check to see that
	      the device is on-line and not reporting any out of paper or other errors.  This  is
	      the correct setting for most versions of lpd.

       -C {on|off}
	      This  option  adds  extra  ("careful") error checking.  When this option is on, the
	      printer driver will ensure that the printer is on-line and not reporting any out of
	      paper  or other errors before sending data.  This is particularly useful for print-
	      ers that normally appear to accept data when turned off.

	      NOTE: This option is obsolete because it's the default in 2.1.131 kernel or later.

       -s     This option returns the current printer status,  both  as  a  decimal  number  from
	      0..255,  and  as	a  list  of active flags.  When this option is specified, -q off,
	      turning off the display of the current IRQ, is implied.

       -T {on|off}
	      This option is obsolete. It was added in Linux 2.1.131, and removed again in  Linux
	      2.3.10. The below is for these old kernels only.

	      This  option  tells the lp driver to trust or not the IRQ.  This option makes sense
	      only if you are using interrupts.  If you tell the lp  driver  to  trust	the  irq,
	      then,  when  the lp driver will get an irq, it will send the next pending character
	      to the printer unconditionally, even if the printer still claims to be BUSY.   This
	      is  the  only  way  to sleep on interrupt (and so the handle the irq printing effi-
	      ciently) at least on Epson Stylus Color  Printers.   The	lp  driver  automagically
	      detects  if  you	could  get improved performance by setting this flag, and in such
	      case it will warn you with a kernel message.

	      NOTE: Trusting the irq is reported to corrupt the printing on  some  hardware,  you
	      must try to know if your printer will work or not...

       -r     This  option  resets  the  port.	 It  requires a Linux kernel version of 1.1.80 or
	      later.

       -q {on|off}
	      This option sets printing the display of the current IRQ setting.

NOTES
       -o, -C, and -s all require a Linux kernel version of 1.1.76 or later.

       -C requires a Linux version prior to 2.1.131.

       -T requires a Linux version of 2.1.131 or later.

BUGS
       By some unfortunate coincidence the ioctl LPSTRICT of 2.0.36 has the same  number  as  the
       ioctl  LPTRUSTIRQ  introduced in 2.1.131. So, use of the -T option on a 2.0.36 kernel with
       an tunelp compiled under 2.1.131 or later may have unexpected effects.

FILES
       /dev/lp?
       /proc/parport/*/*

AVAILABILITY
       The tunelp  command is part of the util-linux package and is available from ftp://ftp.ker-
       nel.org/pub/linux/utils/util-linux/.

tunelp					    7 May 1999					tunelp(8)


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