tunelp - set various parameters for the lp device


   tunelp [options] device


   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.


   -i, --irq argument
          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  interrupts,  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 milliseconds
          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 characters
          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 character 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 otherwise, 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

   -w, --wait milliseconds
          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, --abort <on|off>
          This  is  whether to abort on printer error - the default is not
          to.  If you are sitting 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 trying, and send you mail about it.  The choice is yours.

   -o, --check-status <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, --careful <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  printers
          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, --status
          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, --trust-irq <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 efficiently) 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

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

   -q, --print-irq <on|off>
          This  option  sets  printing  the  display  of  the  current IRQ


   -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.


   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.




   The  tunelp  command is part of the util-linux package and is available
   from Linux Kernel  Archive  ftp://ftp.kernel.org/pub/linux/utils/util-


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