1tunelp(8) Linux Programmer's Manual tunelp(8)
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6 tunelp - set various parameters for the lp device
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9 tunelp device [-i IRQ] [-t TIME] [-c CHARS] [-w WAIT] [-a {on|off}] [-o
10 {on|off}] [-C {on|off}] [-r] [-s] [-q {on|off}] [-T {on|off}]
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13 tunelp sets several parameters for the /dev/lp? devices, for better
14 performance (or for any performance at all, if your printer won't work
15 without it...) Without parameters, it tells whether the device is
16 using interrupts, and if so, which one. With parameters, it sets the
17 device characteristics accordingly. The parameters are as follows:
18 -i IRQ specifies the IRQ to use for the parallel port in question. If
21 this is set to something non-zero, -t and -c have no effect. If
22 your port does not use interrupts, this option will make print‐
23 ing stop. The command tunelp -i 0 restores non-interrupt driven
24 (polling) action, and your printer should work again. If your
25 parallel port does support interrupts, interrupt-driven printing
26 should be somewhat faster and efficient, and will probably be
27 desirable.
28 NOTE: This option will have no effect with kernel 2.1.131 or
30 later since the irq is handled by the parport driver. You can
31 change the parport irq for example via /proc/parport/*/irq.
32 Read /usr/src/linux/Documentation/parport.txt for more details
33 on parport.
34 -t TIME
37 is the amount of time in jiffies that the driver waits if the
38 printer doesn't take a character for the number of tries dic‐
39 tated by the -c parameter. 10 is the default value. If you
40 want fastest possible printing, and don't care about system
41 load, you may set this to 0. If you don't care how fast your
42 printer goes, or are printing text on a slow printer with a buf‐
43 fer, then 500 (5 seconds) should be fine, and will give you very
44 low system load. This value generally should be lower for
45 printing graphics than text, by a factor of approximately 10,
46 for best performance.
47 -c CHARS
50 is the number of times to try to output a character to the
51 printer before sleeping for -t TIME. It is the number of times
52 around a loop that tries to send a character to the printer.
53 120 appears to be a good value for most printers in polling
54 mode. 1000 is the default, because there are some printers that
55 become jerky otherwise, but you must set this to `1' to handle
56 the maximal CPU efficiency if you are using interrupts. If you
57 have a very fast printer, a value of 10 might make more sense
58 even if in polling mode. If you have a really old printer, you
59 can increase this further.
60 Setting -t TIME to 0 is equivalent to setting -c CHARS to infin‐
62 ity.
63 -w WAIT
66 is the number of usec we wait while playing with the strobe sig‐
67 nal. While most printers appear to be able to deal with an
68 extremely short strobe, some printers demand a longer one.
69 Increasing this from the default 1 may make it possible to print
70 with those printers. This may also make it possible to use
71 longer cables. It's also possible to decrease this value to 0 if
72 your printer is fast enough or your machine is slow enough.
73 -a {on|off}
76 This is whether to abort on printer error - the default is not
77 to. If you are sitting at your computer, you probably want to
78 be able to see an error and fix it, and have the printer go on
79 printing. On the other hand, if you aren't, you might rather
80 that your printer spooler find out that the printer isn't ready,
81 quit trying, and send you mail about it. The choice is yours.
82 -o {on|off}
85 This option is much like -a. It makes any open() of this device
86 check to see that the device is on-line and not reporting any
87 out of paper or other errors. This is the correct setting for
88 most versions of lpd.
89 -C {on|off}
92 This option adds extra ("careful") error checking. When this
93 option is on, the printer driver will ensure that the printer is
94 on-line and not reporting any out of paper or other errors
95 before sending data. This is particularly useful for printers
96 that normally appear to accept data when turned off.
97 NOTE: This option is obsolete because it's the default in
99 2.1.131 kernel or later.
100 -s This option returns the current printer status, both as a deci‐
103 mal number from 0..255, and as a list of active flags. When
104 this option is specified, -q off, turning off the display of the
105 current IRQ, is implied.
106 -T {on|off}
109 This option is obsolete. It was added in Linux 2.1.131, and
110 removed again in Linux 2.3.10. The below is for these old ker‐
111 nels only.
112 This option tells the lp driver to trust or not the IRQ. This
114 option makes sense only if you are using interrupts. If you
115 tell the lp driver to trust the irq, then, when the lp driver
116 will get an irq, it will send the next pending character to the
117 printer unconditionally, even if the printer still claims to be
118 BUSY. This is the only way to sleep on interrupt (and so the
119 handle the irq printing efficiently) at least on Epson Stylus
120 Color Printers. The lp driver automagically detects if you
121 could get improved performance by setting this flag, and in such
122 case it will warn you with a kernel message.
123 NOTE: Trusting the irq is reported to corrupt the printing on
125 some hardware, you must try to know if your printer will work or
126 not...
127 -r This option resets the port. It requires a Linux kernel version
130 of 1.1.80 or later.
131 -q {on|off}
134 This option sets printing the display of the current IRQ set‐
135 ting.
136
140 -o, -C, and -s all require a Linux kernel version of 1.1.76 or later.
141 -C requires a Linux version prior to 2.1.131.
143 -T requires a Linux version of 2.1.131 or later.
145
148 By some unfortunate coincidence the ioctl LPSTRICT of 2.0.36 has the
149 same number as the ioctl LPTRUSTIRQ introduced in 2.1.131. So, use of
150 the -T option on a 2.0.36 kernel with an tunelp compiled under 2.1.131
151 or later may have unexpected effects.
152
155 /dev/lp?
156 /proc/parport/*/*
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160 The tunelp command is part of the util-linux-ng package and is avail‐
161 able from ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.
162tunelp 7 May 1999 tunelp(8)