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luit - Locale and ISO 2022 support for Unicode terminals
luit
[ options ] [ -- ] [ program [ args ] ]
Luit is a filter that
can be run between an arbitrary application and a UTF-8 terminal emulator.
It will convert application output from the locale's encoding into UTF-8,
and convert terminal input from UTF-8 into the locale's encoding.
An application
may also request switching to a different output encoding using ISO 2022
and ISO 6429 escape sequences. Use of this feature is discouraged: multilingual
applications should be modified to directly generate UTF-8 instead.
Luit
is usually invoked transparently by the terminal emulator. For information
about running luit from the command line, see EXAMPLES below.
- -h
- Display
some summary help and quit.
- -list
- List the supported charsets and encodings,
then quit.
- -v
- Be verbose.
- -c
- Function as a simple converter from standard input
to standard output.
- -x
- Exit as soon as the child dies. This may cause luit
to loose data at the end of the child's output.
- -argv0 name
- Set the child's
name (as passed in argv[0]).
- -encoding encoding
- Set up luit to use encoding
rather than the current locale's encoding.
- +oss
- Disable interpretation of
single shifts in application output.
- +ols
- Disable interpretation of locking
shifts in application output.
- +osl
- Disable interpretation of character set
selection sequences in application output.
- +ot
- Disable interpretation of
all sequences and pass all sequences in application output to the terminal
unchanged. This may lead to interesting results.
- -k7
- Generate seven-bit characters
for keyboard input.
- +kss
- Disable generation of single-shifts for keyboard
input.
- +kssgr
- Use GL codes after a single shift for keyboard input. By default,
GR codes are generated after a single shift when generating eight-bit keyboard
input.
- -kls
- Generate locking shifts (SO/SI) for keyboard input.
- -gl gn
- Set
the initial assignment of GL. The argument should be one of g0, g1, g2
or g3. The default depends on the locale, but is usually g0.
- -gr gk
- Set the
initial assignment of GR. The default depends on the locale, and is usually
g2 except for EUC locales, where it is g1.
- -g0 charset
- Set the charset initially
selected in G0. The default depends on the locale, but is usually ASCII.
- -g1 charset
- Set the charset initially selected in G1. The default depends
on the locale.
- -g2 charset
- Set the charset initially selected in G2. The
default depends on the locale.
- -g3 charset
- Set the charset initially selected
in G3. The default depends on the locale.
- -ilog filename
- Log into filename
all the bytes received from the child.
- -olog filename
- Log into filename all
the bytes sent to the terminal emulator.
- --
- End of options.
The most
typical use of luit is to adapt an instance of XTerm to the locale's encoding.
Current versions of XTerm invoke luit automatically when it is needed.
If you are using an older release of XTerm, or a different terminal emulator,
you may invoke luit manually:
- $ xterm -u8 -e luit
If you are running in a
UTF-8 locale but need to access a remote machine that doesn't support UTF-8,
luit can adapt the remote output to your terminal:
- $ LC_ALL=fr_FR luit
ssh legacy-machine
Luit is also useful with applications that hard-wire an
encoding that is different from the one normally used on the system or
want to use legacy escape sequences for multilingual output. In particular,
versions of Emacs that do not speak UTF-8 well can use luit for multilingual
output:
- $ luit -encoding 'ISO 8859-1' emacs -nw
And then, in Emacs,
- M-x set-terminal-coding-system
RET iso-2022-8bit-ss2 RET
- /usr/X11R6/lib/X11/fonts/encodings/encodings.dir
- The system-wide encodings directory.
- /usr/X11R6/lib/X11/locale/locale.alias
- The file mapping locales to locale encodings.
On systems with SVR4
(``Unix-98'') ptys (Linux version 2.2 and later, SVR4), luit should be run as
the invoking user.
On systems without SVR4 (``Unix-98'') ptys (notably BSD variants),
running luit as an ordinary user will leave the tty world-writable; this
is a security hole, and luit will generate a warning (but still accept
to run). A possible solution is to make luit suid root; luit should drop
privileges sufficiently early to make this safe. However, the startup code
has not been exhaustively audited, and the author takes no responsibility
for any resulting security issues.
Luit will refuse to run if it is installed
setuid and the underlying system does not have POSIX saved ids.
None
of this complexity should be necessary. Stateless UTF-8 throughout the system
is the way to go.
Charsets with a non-trivial intermediary byte are not
yet supported.
Selecting alternate sets of control characters is not supported
and will never be.
xterm(1)
, unicode(7)
, utf-8(7)
, charsets(7)
. Character
Code Structure and Extension Techniques (ISO 2022, ECMA-35). Control Functions
for Coded Character Sets (ISO 6429, ECMA-48).
Luit was written by Juliusz
Chroboczek <jch@xfree86.org> for the XFree86 project.
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