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LUIT(1)			    General Commands Manual		       LUIT(1)

NAME
       luit - Locale and ISO 2022 support for Unicode terminals

SYNOPSIS
       luit [ options ]	[ -- ] [ program [ args	] ]

DESCRIPTION
       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.

       Luit reads its input from the child process, i.e., an application  run-
       ning in the terminal.  Luit writes its output to	the terminal.  The two
       (input and output) can have different encodings.

       An application may also request switching to a different	output	encod-
       ing  using ISO 2022 and ISO 6429	escape sequences.  Use of this feature
       is discouraged: multilingual applications should	 be  modified  to  di-
       rectly generate UTF-8 instead.

       Luit  is	 usually  invoked transparently	by the terminal	emulator.  For
       information about running luit from the command line, see EXAMPLES  be-
       low.

OPTIONS
       -V     Print luit's version and quit.

       -alias filename
	      the locale alias file
	      (default:	/usr/local/lib/X11/locale/locale.alias).

       -argv0 name
	      Set the child's name (as passed in argv[0]).

       -c     Function	as  a simple converter from standard input to standard
	      output.

       -encoding encoding
	      Set up luit to use encoding rather than the current locale's en-
	      coding.

       -g0 charset
	      Set  the	output	charset	initially selected in G0.  The default
	      depends on the locale, but is usually ASCII.

       -g1 charset
	      Set the output charset initially selected	in  G1.	  The  default
	      depends on the locale.

       -g2 charset
	      Set  the	output	charset	initially selected in G2.  The default
	      depends on the locale.

       -g3 charset
	      Set the output charset initially selected	in  G3.	  The  default
	      depends on the locale.

       -gl gn Set  the	initial	 assignment of GL in the output.  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 in the output.  The default de-
	      pends on the locale, and is usually g2 except for	 EUC  locales,
	      where it is g1.

       -h     Display  a  usage	and options message on the standard output and
	      quit.

       -ilog filename
	      Log into filename	all the	bytes received from the	child.

       -k7    Generate seven-bit characters for	keyboard input.

       -kg0 charset
	      Set the input charset initially selected in G0.  The default de-
	      pends on the locale, but is usually ASCII.

       -kg1 charset
	      Set the input charset initially selected in G1.  The default de-
	      pends on the locale.

       -kg2 charset
	      Set the input charset initially selected in G2.  The default de-
	      pends on the locale.

       -kg3 charset
	      Set the input charset initially selected in G3.  The default de-
	      pends on the locale.

       -kgl gn
	      Set the initial assignment of GL in  the	input.	 The  argument
	      should  be  one of g0, g1, g2 or g3.  The	default	depends	on the
	      locale, but is usually g0.

       -kgr gk
	      Set the initial assignment of GR in the input.  The default  de-
	      pends  on	 the locale, and is usually g2 except for EUC locales,
	      where it is g1.

       -kls   Generate locking shifts (SO/SI) for keyboard input.

       +kss   Disable generation of single-shifts for keyboard input.

       +kssgr Use GL codes after a single shift	for keyboard  input.   By  de-
	      fault, GR	codes are generated after a single shift when generat-
	      ing eight-bit keyboard input.

       -list  List the supported charsets and encodings, then quit.  Luit uses
	      its internal tables for this, which are based on the fontenc li-
	      brary.

       -list-builtin
	      List the built-in	encodings used as a fallback  when  data  from
	      iconv or fontenc is missing.

	      This  option relies on luit being	configured to use iconv, since
	      the fontenc library does not supply a list  of  built-in	encod-
	      ings.

       -list-fontenc
	      List  the	encodings provided by ".enc" files originally distrib-
	      uted with	the fontenc library.

       -list-iconv
	      List the encodings and locales supported by the  iconv  library.
	      Luit adapts its internal tables of fontenc names to iconv	encod-
	      ings.

	      To make scripting	simpler, luit ignores spaces, underscores  and
	      ASCII  minus-signs  (dash) embedded in the names.	 Luit also ig-
	      nores case when matching charset and encoding names.

	      This option lists	only the encodings which are  associated  with
	      the locales supported on the current operating system.  The por-
	      table iconv application provides a list of its supported	encod-
	      ings with	the -l option.	Other implementations may provide sim-
	      ilar functionality.  There is no portable	library	call by	 which
	      an application can obtain	the same information.

       -olog filename
	      Log into filename	all the	bytes sent to the terminal emulator.

       +ols   Disable interpretation of	locking	shifts in application output.

       +osl   Disable  interpretation  of character set	selection sequences in
	      application output.

       +oss   Disable interpretation of	single shifts 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.

       -p     In startup, establish a handshake	between	parent and child  pro-
	      cesses.	This  is  needed for some older	systems, e.g., to suc-
	      cessfully	copy the terminal settings to the pseudo-terminal.

       -prefer list
	      Set the lookup-order preference for character  set  information.
	      The  parameter  is  a comma-separated list of keywords.  The de-
	      fault order (listing all keywords) is

		     fontenc,builtin,iconv,posix

	      The default order	uses fontenc first because this	allows luit to
	      start more rapidly (about	0.1 seconds) than using	iconv for com-
	      plex encodings such as eucJP.  However, you may  find  that  the
	      iconv  implementation  is	 more  accurate	 or complete.  In that
	      case, you	can use	the -show-iconv	option to obtain a  text  file
	      which can	be used	as an encoding with the	fontenc	configuration.

	      This  option relies on luit being	configured to use iconv, since
	      the fontenc library does not provide this	choice.

       -show-builtin encoding
	      Show a built-in encoding,	e.g., from a  ".enc"  file  using  the
	      ".enc" format.

	      This  option relies on luit being	configured to use iconv, since
	      the fontenc library does not supply a list  of  built-in	encod-
	      ings.

       -show-fontenc encoding
	      Show a given encoding, e.g., from	a ".enc" file using the	".enc"
	      format.  If luit is configured to	use the	 fontenc  library,  it
	      obtains  the  information	 using	that  library.	Otherwise luit
	      reads the	file directly.

	      Some of fontenc's	encodings are built  into  the	library.   The
	      fontenc  library	uses  those in preference to an	external file.
	      Use the -show-builtin option to provide similar information when
	      luit is configured to use	iconv.

       -show-iconv encoding
	      Show a given encoding, using the ".enc" format.  If luit is con-
	      figured to use iconv, it obtains the information using that  in-
	      terface.	If iconv cannot	supply the information,	luit may use a
	      built-in table.

       -t     Initialize luit using the	locale and command-line	 options,  but
	      do  not  open a pty connection.  This option is used for testing
	      luit's configuration.  It	will exit with success	if  no	errors
	      were  detected.	Repeat the -t option to	cause warning messages
	      to be treated as errors.

       -v     Be verbose.  Repeating the option, e.g., "-v -v" makes  it  more
	      verbose.	Luit does not use getopt, so "-vv" does	not work.

       -x     Exit  as	soon  as  the child dies.  This	may cause luit to lose
	      data at the end of the child's output.

       --     End of options.

ENVIRONMENT
       Luit uses these environment variables:

       FONT_ENCODINGS_DIRECTORY
	      overrides	the location of	the "encodings.dir" file, which	 lists
	      encodings	in external ".enc" files.

       LC_ALL

       LC_CTYPE

       LANG   During  initialization,  luit  calls  setlocale  to check	if the
	      user's locale is supported by the	operating system.   If	setlo-
	      cale returns a failure, luit looks instead at these variables in
	      succession to obtain any clues from the user's  environment  for
	      locale preference.

       NCURSES_NO_UTF8_ACS
	      Luit sets	this to	tell ncurses to	not rely upon VT100 SI/SO con-
	      trols for	line-drawing.

       SHELL  This is normally set by shells other than	the Bourne shell, as a
	      convention.   Luit  will	use this value (rather than the	user's
	      entry in /etc/passwd) to decide  which  shell  to	 execute.   If
	      SHELL is not set,	luit executes /bin/sh.

EXAMPLES
       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  ma-
       chine  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,  ver-
       sions  of Emacs that do not speak UTF-8 well can	use luit for multilin-
       gual output:

	      $	luit -encoding 'ISO 8859-1' emacs -nw

       And then, in Emacs,

	      M-x set-terminal-coding-system RET iso-2022-8bit-ss2 RET

FILES
       /usr/local/lib/X11/locale/locale.alias
	      The file mapping locales to locale encodings.

SECURITY
       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), run-
       ning 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 cannot	safely
       drop privileges.

BUGS
       None of this complexity should be necessary.  Stateless UTF-8  through-
       out 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.

SEE ALSO
       These are portable:

       o   xterm(1),

       o   ncurses(1).

       These are Linux-specific:

       o   unicode(),

       o   utf-8(),

       o   charsets().

       These are particularly useful:

       o   Character Code Structure and	Extension Techniques (ISO 2022,	ECMA-35)

       o   Control Functions for Coded Character Sets (ISO 6429, ECMA-48)

       o   http://czyborra.com/charsets/

AUTHOR
       Luit was	written	by Juliusz  Chroboczek	<jch@pps.jussieu.fr>  for  the
       XFree86 project.

       Thomas E. Dickey	has maintained luit for	use by xterm since 2006.

				X Window System			       LUIT(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ENVIRONMENT | EXAMPLES | FILES | SECURITY | BUGS | SEE ALSO | AUTHOR

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