TUNELP(8)		     System Administration		     TUNELP(8)

NAME
       tunelp - set various parameters for the lp device

SYNOPSIS
       tunelp [options] device

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.

OPTIONS
       -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/admin-guide/parport.rst 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 infinity.

       -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(2) 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.

       -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 setting.

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

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.

REPORTING BUGS
       For bug reports, use the issue tracker
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY
       The tunelp command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.41.2		  2025-09-22			     TUNELP(8)