189 lines
6.6 KiB
Groff
189 lines
6.6 KiB
Groff
.\" This file Copyright (C) 1992-1997 Michael K. Johnson <johnsonm@redhat.com>
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.\" This file Copyright (C) 1998 Andrea Arcangeli <andrea@e-mind.com>
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.\" It may be distributed under the terms of the GNU General Public License,
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.\" version 2, or any higher version. See section COPYING of the GNU General
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.\" Public license for conditions under which this file may be redistributed.
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.\"
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.\" Polished a bit - aeb
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.TH TUNELP 8 "May 1999" "util-linux" "System Administration"
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.SH NAME
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tunelp \- set various parameters for the lp device
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.SH SYNOPSIS
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.B tunelp
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.I device
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.RB [ \-i
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.IR IRQ ]
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.RB [ \-t
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.IR TIME ]
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.RB [ \-c
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.IR CHARS ]
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.RB [ \-w
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.IR WAIT ]
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.RB [ \-a
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.RB { on | off }]
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.RB [ \-o
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.RB { on | off }]
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.RB [ \-C
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.RB { on | off }]
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.RB [ \-r ]
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.RB [ \-s ]
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.RB [ \-q
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.RB { on | off }]
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.RB [ \-T
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.RB { on | off }]
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.SH DESCRIPTION
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\fBtunelp\fP sets several parameters for the /dev/lp\fI?\fP devices, for better
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performance (or for any performance at all, if your printer won't work
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without it...) Without parameters, it tells whether the device is using
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interrupts, and if so, which one. With parameters, it sets the device
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characteristics accordingly. The parameters are as follows:
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.TP
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.BI \-i " IRQ"
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specifies the IRQ to use for the parallel port in question. If this
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is set to something non-zero, \-t and \-c have no effect. If your port
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does not use interrupts, this option will make printing stop.
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The command
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.B tunelp -i 0
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restores non-interrupt driven (polling) action, and your printer should
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work again. If your parallel port does support interrupts,
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interrupt-driven printing should be somewhat faster and efficient, and
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will probably be desirable.
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NOTE: This option will have no effect with kernel 2.1.131 or later since
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the irq is handled by the parport driver. You can change
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the parport irq for example via
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.IR /proc/parport/*/irq .
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Read
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.I /usr/src/linux/Documentation/parport.txt
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for more details on parport.
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.TP
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.BI \-t " TIME"
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is the amount of time in jiffies that the driver waits if the
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printer doesn't take a character for the number of tries dictated by
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the \-c parameter. 10 is the default value. If you want fastest
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possible printing, and don't care about system load, you may set this
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to 0. If you don't care how fast your printer goes, or are printing
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text on a slow printer with a buffer, then 500 (5 seconds) should be
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fine, and will give you very low system load. This value generally
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should be lower for printing graphics than text, by a factor of
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approximately 10, for best performance.
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.TP
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.BI \-c " CHARS"
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is the number of times to try to output a character to the
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printer before sleeping for \-t \fITIME\fP. It is the number of times around
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a loop that tries to send a character to the printer. 120 appears to
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be a good value for most printers in polling mode. 1000 is the default,
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because there are some printers that become jerky otherwise, but you \fImust\fP
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set this to `1' to handle the maximal CPU efficiency if you are using
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interrupts. If you have a very fast printer, a value of 10 might make more
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sense even if in polling mode.
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If you have a \fIreally\fP old printer, you can increase this further.
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Setting \-t \fITIME\fP to 0 is equivalent to setting \-c \fICHARS\fP
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to infinity.
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.TP
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.BI \-w " WAIT"
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is the number of usec we wait while playing with the strobe signal.
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While most printers appear to be able to deal with an extremely
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short strobe, some printers demand a longer one. Increasing this from
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the default 1 may make it possible to print with those printers. This may also
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make it possible to use longer cables. It's also possible to decrease this
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value to 0 if your printer is fast enough or your machine is slow enough.
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.TP
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.BR \-a " {" on | off }
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This is whether to abort on printer error - the default
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is not to. If you are sitting at your computer, you probably want to
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be able to see an error and fix it, and have the printer go on
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printing. On the other hand, if you aren't, you might rather that
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your printer spooler find out that the printer isn't ready, quit
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trying, and send you mail about it. The choice is yours.
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.TP
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.BR \-o " {" on | off }
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This option is much like \-a. It makes any
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.I open()
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of this device check to see that the device is on-line and not reporting any
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out of paper or other errors. This is the correct setting for most
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versions of lpd.
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.TP
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.BR \-C " {" on | off }
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This option adds extra ("careful") error checking. When
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this option is on, the printer driver will ensure that the printer is
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on-line and not reporting any out of paper or other errors before
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sending data. This is particularly useful for printers that normally
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appear to accept data when turned off.
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NOTE: This option is obsolete because it's the default in 2.1.131 kernel
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or later.
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.TP
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.B \-s
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This option returns the current printer status, both as a
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decimal number from 0..255, and as a list of active flags. When
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this option is specified, \-q off, turning off the display of the
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current IRQ, is implied.
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.TP
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.BR \-T " {" on | off }
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This option is obsolete. It was added in Linux 2.1.131,
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and removed again in Linux 2.3.10. The below is for these
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old kernels only.
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This option tells the lp driver to trust or not the IRQ.
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This option makes sense only if you are using interrupts.
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If you tell the lp driver to trust the irq, then, when the lp driver will
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get an irq, it will send the next pending character to the printer
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unconditionally, even if the printer still claims to be BUSY.
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This is the only way to sleep on interrupt (and so the handle the irq
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printing efficiently) at least on Epson Stylus Color Printers.
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The lp driver automagically detects if you could get improved
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performance by setting this flag, and in such case it will warn you
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with a kernel message.
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NOTE: Trusting the irq is reported to corrupt the printing on some hardware,
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you must try to know if your printer will work or not...
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.TP
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.B \-r
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This option resets the port. It requires a Linux kernel version of
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1.1.80 or later.
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.TP
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.BR \-q " {" on | off }
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This option sets printing the display of the current IRQ setting.
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.SH NOTES
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.BR \-o ,
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.BR \-C ,
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and
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.B \-s
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all require a Linux kernel version of 1.1.76 or later.
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.B \-C
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requires a Linux version prior to 2.1.131.
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.B \-T
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requires a Linux version of 2.1.131 or later.
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.SH BUGS
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By some unfortunate coincidence the ioctl LPSTRICT of 2.0.36 has the same
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number as the ioctl LPTRUSTIRQ introduced in 2.1.131. So, use of the \-T option
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on a 2.0.36 kernel with an tunelp compiled under 2.1.131 or later may have
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unexpected effects.
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.SH FILES
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.I /dev/lp?
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.br
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.I /proc/parport/*/*
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.SH AVAILABILITY
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The tunelp command is part of the util-linux package and is available from
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ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
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