Using qed on non-QNX terminal types

Setting Your Terminal Type

When qed is invoked, it uses terminal capabilities described in the terminfo entry for the terminal type set in the TERM environment variable. The qed editor was written specifically for the original QNX console terminal type (TERM=QNX) and the IBM PC keyboard. Depending on the console driver in use, your system may be using either ANSI based screen controls (Dev.ansi) or QNX screen controls (Dev.con). When used on an ANSI-based terminal, some key combinations may not work.

Most of the basic keycodes needed by qed are described in extra terminfo capabilities that are included in the terminfo files for the terminal components shipped with QNX; this includes Dev.ansi (terminal type qansi) and xterm (terminal type xterm). For other terminal types you may need to add capabilities to make qed function acceptably well.

The following is a table of the mappings for the terminfo capabilities used by qed:

Required Terminal Capabilities

Any terminal which is to be used with qed must support the following capabilities:

• Direct Cursor Addressing
• Screen Clearing
• Zero width escape sequences

The last point requires further explanation. On some terminals, an escape sequence to turn on inverse video takes up a character position on the line. As a result your standard 80 column line will be reduced to 78 columns (one character to turn on, and one character to turn off) The qed editor does not work properly on this type of terminal. Escape sequences must not take any physical room on the screen.

Although not required, the following capabilities are recommended

• Clear to end of line.
• Insert and delete line.
• Inverse video (and to a lesser extent underline).
• Up, down, left and right cursor keys.

The first two will speed up display updates while the third is necessary for displaying tagged blocks of text. If your terminal supports Highlighting or underline, but not inverse video, then qed will attempt to display tagged areas of text using these capabilities. Without cursor keys, the editor may be painful to use.

Screen Output

qed will adjust its output to conform to your terminal's screen size. Display updates will be determined by the baud rate if qed is being run from an attached terminal. This will be considerably slower than running qed on a console, xterm etc. Non-ASCII characters (0x00-0x1f and 0x7e-0xff) will be displayed as a question (?) mark. They are saved and manipulated as the characters they really represent. It is only the display which prints them as question marks.

Note: on attached terminals, the column position is NOT updated as you move your cursor. To force an update you must type the <SHOW> key, which on a PC keyboard, is the center key (5) on the numeric keypad when Num Lock is turned off.

Keyboard Input

It is keyboard input which really differentiates using qed on a QNX terminal type from qed on a non-QNX terminal. The console keyboard is rich in both function and cursor keys. Unfortunately, most terminals are rather limited in the special keys that they provide. To overcome this it is often necessary to enter a two or three character sequence to simulate a single console key. The terminal database defines keys according to their function. For example, the large + key on the console keyboard's numeric keypad is called the “select” key. It is used by qed to leave some form of input mode and return back to a command state. This key is very seldom found on a terminal, so you will have to add a kslt capability to your terminal type. Note that this should be something sent by one keystroke unless you have very fast fingers -- the timeout between characters of multi-character keycodes is quite quick.

There is no provision for executing any of the Alt letter keys such as Alt-b to turn on option blank. You will have to go to the command line and type the option command directly. (ob+ or ob-)

You may examine the escape sequences in effect for your terminal by using the infocmp utility. For more information, see the Utilities Reference.