1tunelp(8) Linux Programmer's Manual tunelp(8)
2
6 tunelp - set various parameters for the lp device
7
9 tunelp <device> [-i <IRQ> | -t <TIME> | -c <CHARS> | -w <WAIT> | -a
10 [on|off] | -o [on|off] | -C [on|off] | -r | -s | -q [on|off] | - T
11 [on|off] ]
12
14 tunelp sets several parameters for the /dev/lp? devices, for better
15 performance (or for any performance at all, if your printer won't work
16 without it...) Without parameters, it tells whether the device is
17 using interrupts, and if so, which one. With parameters, it sets the
18 device characteristics accordingly. The parameters are as follows:
19 -i <IRQ>
22 specifies the IRQ to use for the parallel port in question. If
23 this is set to something non-zero, -t and -c have no effect. If
24 your port does not use interrupts, this option will make print‐
25 ing stop. The command tunelp -i 0 restores non-interrupt driven
26 (polling) action, and your printer should work again. If your
27 parallel port does support interrupts, interrupt-driven printing
28 should be somewhat faster and efficient, and will probably be
29 desirable.
30 NOTE: This option will have no effect with kernel 2.1.131 or
32 later since the irq is handled by the parport driver. You can
33 change the parport irq for example via /proc/parport/*/irq.
34 Read /usr/src/linux/Documentation/parport.txt for more details
35 on parport.
36 -t <TIME>
39 is the amount of time in jiffies that the driver waits if the
40 printer doesn't take a character for the number of tries dic‐
41 tated by the -c parameter. 10 is the default value. If you
42 want fastest possible printing, and don't care about system
43 load, you may set this to 0. If you don't care how fast your
44 printer goes, or are printing text on a slow printer with a buf‐
45 fer, then 500 (5 seconds) should be fine, and will give you very
46 low system load. This value generally should be lower for
47 printing graphics than text, by a factor of approximately 10,
48 for best performance.
49 -c <CHARS>
52 is the number of times to try to output a character to the
53 printer before sleeping for -t <TIME>. It is the number of
54 times around a loop that tries to send a character to the
55 printer. 120 appears to be a good value for most printers in
56 polling mode. 1000 is the default, because there are some
57 printers that become jerky otherwise, but you must set this to
58 `1' to handle the maximal CPU efficiency if you are using inter‐
59 rupts. If you have a very fast printer, a value of 10 might make
60 more sense even if in polling mode. If you have a really old
61 printer, you can increase this further.
62 Setting -t <TIME> to 0 is equivalent to setting -c <CHARS> to
64 infinity.
65 -w <WAIT>
68 is the number of usec we wait while playing with the strobe sig‐
69 nal. While most printers appear to be able to deal with an
70 extremely short strobe, some printers demand a longer one.
71 Increasing this from the default 1 may make it possible to print
72 with those printers. This may also make it possible to use
73 longer cables. It's also possible to decrease this value to 0 if
74 your printer is fast enough or your machine is slow enough.
75 -a [on|off]
78 This is whether to abort on printer error - the default is not
79 to. If you are sitting at your computer, you probably want to
80 be able to see an error and fix it, and have the printer go on
81 printing. On the other hand, if you aren't, you might rather
82 that your printer spooler find out that the printer isn't ready,
83 quit trying, and send you mail about it. The choice is yours.
84 -o [on|off]
87 This option is much like -a. It makes any open() of this device
88 check to see that the device is on-line and not reporting any
89 out of paper or other errors. This is the correct setting for
90 most versions of lpd.
91 -C [on|off]
94 This option adds extra ("careful") error checking. When this
95 option is on, the printer driver will ensure that the printer is
96 on-line and not reporting any out of paper or other errors
97 before sending data. This is particularly useful for printers
98 that normally appear to accept data when turned off.
99 NOTE: This option is obsolete because it's the default in
101 2.1.131 kernel or later.
102 -s This option returns the current printer status, both as a deci‐
105 mal number from 0..255, and as a list of active flags. When
106 this option is specified, -q off, turning off the display of the
107 current IRQ, is implied.
108 -T [on|off]
111 This option is obsolete. It was added in Linux 2.1.131, and
112 removed again in Linux 2.3.10. The below is for these old ker‐
113 nels only.
114 This option tells the lp driver to trust or not the IRQ. This
116 option makes sense only if you are using interrupts. If you
117 tell the lp driver to trust the irq, then, when the lp driver
118 will get an irq, it will send the next pending character to the
119 printer unconditionally, even if the printer still claims to be
120 BUSY. This is the only way to sleep on interrupt (and so the
121 handle the irq printing efficiently) at least on Epson Stylus
122 Color Printers. The lp driver automagically detects if you
123 could get improved performance by setting this flag, and in such
124 case it will warn you with a kernel message.
125 NOTE: Trusting the irq is reported to corrupt the printing on
127 some hardware, you must try to know if your printer will work or
128 not...
129 -r This option resets the port. It requires a Linux kernel version
132 of 1.1.80 or later.
133 -q [on|off]
136 This option sets printing the display of the current IRQ set‐
137 ting.
138
142 -o, -C, and -s all require a Linux kernel version of 1.1.76 or later.
143 -C requires a Linux version prior to 2.1.131.
145 -T requires a Linux version of 2.1.131 or later.
147
150 By some unfortunate coincidence the ioctl LPSTRICT of 2.0.36 has the
151 same number as the ioctl LPTRUSTIRQ introduced in 2.1.131. So, use of
152 the -T option on a 2.0.36 kernel with an tunelp compiled under 2.1.131
153 or later may have unexpected effects.
154
157 /dev/lp?
158 /proc/parport/*/*
159tunelp 7 May 1999 tunelp(8)