1INB(1)                             I/O Ports                            INB(1)
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NAME

6       inb, outb, inw, outw, inl, outl - access I/O ports
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SYNOPSIS

9        inb ADDRESS
10        inw ADDRESS
11        inl ADDRESS
12        outb ADDRESS DATA
13        outw ADDRESS DATA
14        outl ADDRESS DATA
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EXAMPLES

17        inb 0x278
18        outw 0x440 0xffff
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DESCRIPTION

21       These commands enable command line and script access directly to I/O
22       ports on PC hardware.
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24       The "inb", "inw" and "inl" commands perform an input (read) operation
25       on the given I/O port, and print the result.
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27       The "outb", "outw" and "outl" commands perform an output (write)
28       operation to the given I/O port, sending the given data.  Note that the
29       order of the parameters is ADDRESS DATA.
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31       The size of the operation is selected according to the suffix, with "b"
32       meaning byte, "w" meaning word (16 bits) and "l" meaning long (32
33       bits).
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35       Port numbers are in the range 0-0xffff.  We don't support access to
36       memory mapped devices.
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38       Hexadecimal numbers (prefixed by "0x"), decimal numbers, and octal
39       numbers (prefixed by 0), are allowed as parameters.
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RETURN FROM "IN" OPERATIONS

42       The value read from the port by an "in" operation is normally printed
43       in decimal.
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45       Use the "--hex" option to print the result as hexadecimal ("0x" prefix
46       is NOT printed).
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48       Use the "--code" option to turn the result into an exit status.  Note
49       that Unix/shell can only reliably return exit status in the range
50       0-0x7f, so this is not particularly useful in practice.
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TYPE AND SIZE OF OPERATION

53       The type and size of the operation is normally determined by the name
54       of the command, eg. "inb" is a read operation of 1 byte.
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56       You can override this by using the "--read", "--write" and/or "--size
57       N" options.  For "--size N", "N" should be 1, 2 or 4 meaning byte, word
58       and long respectively.
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PERMISSIONS

61       You would normally need to be root or have the "CAP_SYS_RAWIO"
62       capability in order to run these commands.
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WARNING

65       Using these commands can cause Bad Things to happen to your hardware.
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SEE ALSO

68       iopl(2), mem(4), <http://et.redhat.com/~rjones/ioport>,
69       <http://www.faqs.org/docs/Linux-mini/IO-Port-Programming.html>.
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AUTHORS

72       Richard W.M. Jones <rjones @ redhat . com>
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75       (C) Copyright 2009 Red Hat Inc., <http://et.redhat.com/~rjones/ioport>.
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77       This program is free software; you can redistribute it and/or modify it
78       under the terms of the GNU General Public License as published by the
79       Free Software Foundation; either version 2 of the License, or (at your
80       option) any later version.
81
82       This program is distributed in the hope that it will be useful, but
83       WITHOUT ANY WARRANTY; without even the implied warranty of
84       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
85       General Public License for more details.
86
87       You should have received a copy of the GNU General Public License along
88       with this program; if not, write to the Free Software Foundation, Inc.,
89       675 Mass Ave, Cambridge, MA 02139, USA.
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93ioport-1.2                        2022-01-20                            INB(1)
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