Provided by: luit_2.0.20221028-1_amd64 bug

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 running 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 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.

OPTIONS

       -V     Print luit's version and quit.

       -alias filename
              the locale alias file
              (default: unknown).

       -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 encoding.

       -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 depends 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 depends on the locale,
              but is usually ASCII.

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

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

       -kg3 charset
              Set the input charset initially selected in G3.  The default depends 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 depends 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 default, GR codes are
              generated after a single shift when generating 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 library.

       -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 encodings.

       -list-fontenc
              List the encodings provided by “.enc” files originally distributed 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 encodings.

              To  make  scripting simpler, luit ignores spaces, underscores and ASCII minus-signs
              (dash) embedded in the names.  Luit also ignores 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 portable iconv application provides
              a  list  of  its supported encodings with the -l option.  Other implementations may
              provide similar 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  processes.   This  is
              needed  for some older systems, e.g., to successfully 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 default 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 complex 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 encodings.

       -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 configured to use
              iconv, it obtains the information using that interface.  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 setlocale  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  controls  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 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

FILES

       unknown
              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),  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 cannot safely drop privileges.

BUGS

       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.

SEE ALSO

       These are portable:

       •   xterm(1),

       •   ncurses(3X).

       These are Linux-specific:

       •   unicode(1),

       •   utf-8(1),

       •   charsets(1).

       These are particularly useful:

       •   Character Code Structure and Extension Techniques (ISO 2022, ECMA-35)Control Functions for Coded Character Sets (ISO 6429, ECMA-48)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)