bterm command

Purpose

Emulates terminals in bidirectional (BIDI) mode.

Syntax

bterm [ -maps Map ] [ -help ] [ -keywords ] [ -nobidi ] [ -symmetric ] [ -autopush ] [ -or Orientation ] [ -text TextType ] [ -nss NumShape ] [ -csd CharShape ] [ -tail ] [ -nonulls ]

Description

The bterm command emulates the IBM® 3151, VT220, HFT and other terminals. It operates in BIDI mode on ASCII terminals. This command creates a BIDI shell that can run any BIDI application. You cannot initiate the bterm command recursively from within itself.

The maps that determine the keyboard mapping and the symmetric swapping of characters are specified by the -maps flag. You can specify other BIDI behaviors using the flags available to the bterm command or by setting them in the defaults files. Such behaviors include the default text mode, the default screen orientation, the default mode of Arabic character shaping, the default shape of numerals, whether the Symmetric Swapping mode is enabled and whether the Autopush mode is enabled or not. The behaviors specified with flags take precedence over the behaviors set in the defaults files.

The default files are searched in the following order:

  1. The .Bidi-defaults file is searched for in your home directory.
  2. If the file is not found, the bterm command searches for the BTerm resource file in the /usr/lib/nls/bidi/$LANG/app-defaults file.

Flags

Item Description
-autopush Enables the Autopush mode in visual text mode.
-csd CharShape Specifies the shape of Arabic characters. The CharShape variable can be one of the following options:
  • automatic
  • isolated (visual text mode only)
  • initial (visual text mode only)
  • middle (visual text mode only)
  • final (visual text mode only)
  • passthru

    The default is automatic shaping.

-help Lists the available parameters and their syntax.
-keywords Lists the keywords available in defaults file.
-maps Map Specifies the map used for keyboard mapping and symmetric swapping of characters. Each language has a different map, and the available options for the Map variable are in the /usr/lib/nls/bidi/maps directory. You must specify the environment variable BIDIPATH as follows:
export BIDIPATH=/usr/lib/nls/bidi 
-nobidi Disables the BIDI mode.
-nonulls Initializes the screen with spaces instead of nulls.
-nss NumShape Specifies the shape of the numerals. Specify one of the following options for the NumShape variable:
  • bilingual
  • hindi
  • arabic
  • passthru

The default is bilingual.

-or Orientation Specifies screen orientation. The Orientation variable can be either LTR or RTL. The default is LTR.
-symmetric Enables the Symmetric Swapping mode.
-tail Writes the "seen," "sheen," "sad," and "dad" characters of the Arabic language in two cells instead of one cell.
-text TextType Specifies the type of data stream. The TextType variable can be either implicit or visual. The default is implicit.

Key Combinations

To change the BIDI settings using key combinations, press the Ctrl+X key sequence to enter a BIDI command mode. Any key you type after this key sequence is interpreted as a BIDI command. Invalid keys sound a beep and exit the BIDI command mode. The following keys are valid BIDI commands:

Key Purpose
r Reverses the screen orientation.
n Sets the language keyboard layer to National.
l Sets the language keyboard layer to Latin.
a Toggles the automatic shaping variable option of the Arabic characters (valid also for Implicit mode).
t Displays the status.
space Enters a required space (RSP).

For implicit mode only:

Key Purpose
c Toggles the column heading mode.

For visual mode only:

Key Purpose
s Initiates the Push mode.
e Terminates the End Push mode.
p Toggles the Autopush mode.
f Shapes Arabic characters in their final forms.
i Shapes Arabic characters in their initial forms.
b Shapes Arabic characters in the Passthru mode.
o Shapes Arabic characters in their isolated forms.
m Shapes Arabic characters in their middle forms.

.Bidi-defaults Keywords

Use the following keywords to set the defaults for the bterm command.

.Bidi-defaults Keywords
Keywords Value/Effect
fScrRev
on
Screen reverse function key is enabled.
off
Screen reverse function key is disabled.
fRTL
on
RTL keyboard layer function key is enabled.
off
RTL keyboard layer function key is disabled.
fLTR
on
LTR keyboard layer function key is enabled.
off
LTR keyboard layer function key is disabled.
fPush
on
Push function key is enabled.
off
Push function key is disabled.
fEndPush
on
End Push function key is enabled.
off
End Push function key is disabled.
fAutoPush
on
AutoPush function key is enabled.
off
AutoPush function key is disabled.
fASD
on
Automatic Shape Determination function key is enabled.
off
Automatic Shape Determination function key is disabled.
fShapeIS
on
Isolated Shape function key is enabled.
off
Isolated Shape function key is disabled.
fShapeIN
on
Initial Shape function key is enabled.
off
Initial Shape function key is disabled.
fShapeM
on
Middle Shape function key is enabled.
off
Middle Shape function key is disabled.
fShapeF
on
Final Shape function key is enabled.
off
Final Shape function key is disabled.
textType
implicit
Type of data stream is set to Implicit.
visual
Type of data stream is set to Visual.
orientation
LTR
Left-to-right default screen orientation.
RTL
Right-to-left default screen orientation.
symmetric
on
Symmetric Swapping enabled.
off
Symmetric Swapping disabled.
numShape
bilingual
Numeral shaping is set to bilingual.
hindi
Numerals are represented in Hindi.
arabic
Numeral shaping is set in Arabic/Hebrew.
passthru
Numerals are represented in passthru.
charShape
automatic
Arabic characters are shaped automatically.
passthru
Arabic characters are displayed in passthru mode.
isolated
Arabic characters are displayed in isolated mode.
initial
Arabic characters are displayed in initial mode.
final
Arabic characters are displayed in final mode.
middle
Arabic characters are displayed in middle mode.
maps Specifies the page code directory to be used for Keyboard. layering, input, output and symmetric character swapping.
expandTail
on
Writes "seen"-like characters and their tails on two cells.
off
Writes "seen"-like characters and their tails on one cell.
nobidi
on
Activates BIDI mode.
off
Turn off BIDI mode.
noNulls
on
Replaces nulls by spaces.
off
Leaves nulls as null, no replacement of spaces.