mapchan(1M) mapchan(1M)
NAME
mapchan - Configure tty device mapping.
SYNOPSIS
mapchan [-ans] [-f mapfile] [channels . . .]
mapchan [-o] [-d] [channel]
DESCRIPTION
mapchan configures the mapping of information input and output
of the UNIX system. The mapchan utility is intended for users
of applications that employ languages other than English
(character sets other than 7 bit ASCII).
mapchan translates codes sent by peripheral devices, such as
terminals, to the internal character set used by the UNIX
system. mapchan can also map codes in the internal character
set to other codes for output to peripheral devices (such as
terminals, printers, console screen, etc.). Note that PC
keyboard configuration is accomplished through the mapkey(1M)
utility.
mapchan has several uses: to map a channel (-a or -s); to
unmap a channel (-n and optionally -a); or to display the map
on a channel (optionally -o,-d, channels).
mapchan with no options displays the map on the user's
channel. The map displayed is suitable as input for mapchan.
The options are :
-a When used alone, sets all channels given in the default
file (/etc/default/mapchan) with the specified map.
When used with -n, it refers to all channels given in
the default file. A privileged user can map or unmap
all channels, other users can map only channels they
own. The -a option can not be used with the -d, -o, or
-s options.
-d Causes the mapping table currently in use on the given
device, channel, to be displayed in decimal instead of
the default hexadecimal. An ASCII version is displayed
on standard output. This output is suitable as an input
file to mapchan for another channel. Mapped values are
displayed. Identical pairs are not output. The -d
option can not be used with -a, -f, -n, -o or -s
options.
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mapchan(1M) mapchan(1M)
-f Causes the current channel or list of channels to be
mapped with mapfile. The -f option can not be used with
-d, -n, -s, or -o options.
-n Causes null mapping to be performed. All codes are
input and output as received. Mapping is turned off for
the user's channel or for other channels, if given. -a
used with -n will turn mapping off for all channels
given in the default file. This is the default mapping
for all channels unless otherwise configured. The -n
option can not be used with -d, -f, -o, or -s options.
-o Causes the mapping table currently in use on the given
device, channel, to be displayed in octal instead of the
default hexadecimal. An ASCII version is displayed on
standard output. This output is suitable as an input
file to mapchan for another port. Mapped values are
displayed. Identical pairs are not output. The -o
option can not be used with -a, -d, -f, -n, or -s
options.
-s Sets the user's current channel with the mapfile given
in the default file. The -s option can not be used with
any other option.
The user must own the channel in order to map it. The
privileged user can map any channel. Read or write permission
is required to display the map on a channel.
Each tty device channel (display adapter and video monitor on
computer, parallel port, serial port, etc.) can have a
different map. When the UNIX system boots, mapping is off for
all channels.
mapchan is usually invoked in the /etc/rc2 file. This file is
executed when the system enters the multiuser mode and sets up
the default mapping for the system. Users can invoke mapchan
when they log in by including a mapchan command line in their
.profile or In addition, users can remap their channel at any
time by invoking mapchan from the command line. channels not
listed in the default file are not automatically mapped.
channels are not changed on logout. Whatever mapping was in
place for the last user remains in effect for the next user,
unless they modify their .profile or .login file.
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mapchan(1M) mapchan(1M)
For example, the default file /etc/default/mapchan can obtain:
tty1
tty2 ibm
tty3 wy60.ger
lp ibm
The default directory containing mapfiles is /usr/lib/mapchan.
The default directory containing channel files is /dev. Full
pathnames may be used for channels or mapfiles. If a channel
has no entry, or the entry field is blank, no mapping is
enabled on that channel. Additional channels added to the
system (for example, adding a serial or parallel port), are
not automatically entered in the mapchan default file. If
mapping is required, the system administrator must make the
entries. The format of the mapfiles is documented in the
mapchan(4) manual page.
Using a Mapped channel
The input information is assumed to be 7-or 8-bit codes sent
by the peripheral device. The device may make use of dead or
compose keys to produce the codes. If the device does not
have dead or compose keys, these keys can be simulated using
mapchan.
One to one mapped characters are displayed when the key is
pressed and the mapped value is passed to the kernel.
Certain keys are designated as dead keys in the mapfile. Dead
key sequences are two keystrokes that produce a single mapped
value that is passed to the kernel. The dead key is usually a
diacritical character, the second key is usually the letter
being modified. For example, the sequence 'e could be mapped
to the ASCII value 0xE9, and displayed as e'.
One key is designated as the compose key in the mapfile.
Compose key sequences are composed of three keystrokes that
produce a single mapped value that is passed to the kernel.
The compose key is usually a seldom used character or CTRL-
letter combination. The second key is usually the letter
being modified. The third key may be another character being
combined, or a diacritical character.
For example, if @ is the compose key, the sequence @ c O
could be mapped to the ASCII value 0xA9, and displayed as O.
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mapchan(1M) mapchan(1M)
Characters are not echoed to the screen during a dead or
compose sequence. The mapped character is echoed and passed
to the kernel once the sequence is correctly completed.
Characters are always put through the input map, even when
part of dead or compose sequences. The character is then
checked for the internal value. The value may also be mapped
on output. This should be kept mind when preparing map files.
The following conditions will cause an error during input:
1. non-recognized (not defined in the mapfile) dead or
compose sequence.
2. restarting a compose sequence before completion by
pressing the compose key in the middle of a dead or
compose sequence (this is an error, but a new compose
sequence is initiated).
If the mapfile contains the keyword beep, a bell sounds when
either of the above conditions occurs. In either case, the
characters are not echoed to the screen, or passed to the
kernel.
In order to allow for character sequences sent to control the
terminal (move the cursor, and so on) rather than to print
characters on the screen, mapchan allows characters sequences
to be specified as special sequences which are not passed
through the normal mapping procedure. Two sections may be
specified, one for each of the input (keyboard) and output
(screen) controls.
Character Sets
The internal character set used is defined by the mapfiles
used. By default, this is the ISO 8859/1 character set which
is also known as dpANS X3.4.2 and ISO/TC97/SC2. It supports
most of the Latin alphabet and can represent most European
languages.
Several partial map files are provided as examples. They must
be modified for use with specific peripheral devices. Consult
your hardware manual for the codes needed to display the
desired characters. Two map files are provided for use with
the console device: /usr/lib/mapchan/ibm for systems with a
standard PC character set ROM, and /usr/lib/mapchan/iso for
systems with an optional ISO 8859/1 character set ROM.
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mapchan(1M) mapchan(1M)
Care should be taken that the stty settings [see stty(1)] are
correct for 8-bit terminals. The /etc/gettydefs file may
require modifications to allow logging with the correct
settings.
7-bit U.S ASCII (ANSI X3.4) should be used if no mapping is
enabled on the channel.
FILES
/etc/default/mapchan
/usr/lib/mapchan/*
NOTICES
Some non-U.S keyboards and display devices do not support
characters commonly used by command shells and the C
programming language. It is not recommended that these
devices be used for system administration tasks.
Printers can be mapped, output only, and can either be sent
8-bit codes or one-to-many character strings using mapchan.
Line printer spooler interface scripts can be used (setuid
root) to change the output map on the printer when different
maps are required (as in changing print wheels to display a
different character set). See lpadmin(1M) and lp(7) for
information on installing and administering interface scripts.
Not all terminals or printers can display all the characters
that can be represented using this utility. Refer to the
device's hardware manual for information on the capabilities
of the peripheral device.
Use of mapfiles that specify a different internal character
set per channel, or a set other than the 8-bit ISO 8859 set
supplied by default can cause strange side effects. It is
especially important to retain the 7-bit ASCII portion of the
character set [see ascii(5)]. System utilities and many
applications assume these values.
Media transported between machines with different internal
code set mappings may not be portable as no mapping is
performed on block devices, such as tape and floppy drives.
However, trchan with an appropriate mapfile can be used to
translate from one internal character set to another.
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mapchan(1M) mapchan(1M)
Do not set ISTRIP [see stty(1)] when using mapchan. This
option causes the eighth bit to be stripped before mapping
occurs.
REFERENCES
ascii(5), keyboard(7), lp(7), lpadmin(1M), mapchan(4),
mapkey(1M), stty(1)
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