path: root/listbas.rst

=======
listbas
=======

--------------------------------------------------------
List the source of a tokenized Atari 8-bit BASIC program
--------------------------------------------------------

.. include:: manhdr.rst

SYNOPSIS
========

listbas [**-v**] [**-i**] [**-b**] [**-d** ] [**-a** | **-m** ] **input-file**

DESCRIPTION
===========

**listbas** acts like the *LIST* command in BASIC. It reads a
tokenized (SAVEd) BASIC program and prints the code in human-readable
format.

By default, output is Unicode in UTF-8 encoding, with ANSI/VT220
escape sequences for inverse video and color syntax highlighting.

OPTIONS
=======

Output modes
------------

The default output mode is Unicode/UTF-8 representations of ATASCII
characters.

**-U**
  Output Unicode/UTF-8 representations of ATASCII characters. This is
  the default output mode; the **-U** option is provided so you can
  override **-a**, **-d**, **-m**, **-x** in **LISTBAS_OPTS** (see
  **ENVIRONMENT**, below).

**-x**
  Output Unicode/UTF-8 representations of the XL International Character
  Set, rather than ATASCII.

**-a**
  Output raw ATASCII; no translation to the host character set. Must be
  used with redirection; **listbas** will not write ATASCII to the terminal.

**-m**
  Output "magazine listing". See the **-m** option for **a8cat**\(1) for details.
  Color is supported in this mode. No Unicode/UTF-8 characters are printed in
  this mode.

**-d**
  Print dots rather than Unicode/UTF-8 characters. Color and inverse
  video are still supported in this mode, but no Unicode/UTF8 characters
  are printed. Use this only if your terminal *really* doesn't support
  Unicode (e.g. **rxvt**\(1))... but even then, **-m** is preferred,
  because you can't tell what the dots are supposed to represent.

Other options
-------------

**-i**
  Include the immediate mode command (line 32768) in the output.

**-C**
  Enable color syntax highlighting. This option is enabled by default;
  the **-C** option is provided so you can override **-n** in
  **LISTBAS_OPTS** (see **ENVIRONMENT**, below).

**-n**
  No color. Has no effect if **-a** is in effect, since this
  mode doesn't support color anyway. Disabling color does not
  disable reverse video.

**-b**
  Use bold for color output. This may make it easier to read on
  some terminals. Or, it may hurt your eyes...

**-u**
  Use underlining for inverse video, rather than reverse video output.

**-c** *colors*
  Customize the color scheme. See **COLORS**, below, for the format of the
  *colors* argument. Once you've found a set of colors you like,
  you can place this option in the **LISTBAS_OPTS** environment variable
  to use your colors by default. See **ENVIRONMENT**, below.

.. include:: genopts.rst

COLORS
======

Color output only works on terminal emulators (or real terminals)
that support ANSI/VT220 style escape codes. This includes all modern
terminal emulators, and most not-so-modern ones in the UNIX world.

The color scheme is adjustable via the **-c** option; see
**Customization**, below. To avoid having to give your custom colors on
the command line every time, see **ENVIRONMENT**, below.

The default color scheme is:

**yellow**
  Commands. Also "command operators" such as the **GOTO** in **ON/GOTO** and
  the **STEP** in a **FOR** command. These are really operators as far as
  BASIC is concerned, but it makes more sense to colorize them as commands.

**green**
  Operators (except functions and "command operators").

**purple**
  Functions.

**red**
  Numbers (except line numbers at the start of a line) and string
  constants (but not the quotes around the string).

**cyan**
  Line numbers at the start of a line, comments (**REM** text) and **DATA** elements.

**uncolorized**
  Variable names.

Quotes around strings and commas between **DATA** elements are
never colorized, so they'll appear in the default foreground color
(usually white if the terminal has a black background, or black if the
background is white).

Note that nothing is blue in the default color scheme. This is because
it's difficult to read on many terminals. Also, black and white are
not used because presumably, one or the other is the background color
of the terminal.

Customization
-------------
You can customize the colors by using the **-c** *colors* option, either
on the command line, or in the **LISTBAS_OPTS** environment variable.
*colors* is a string of exactly 6 characters, each of which must be the
digits *0* through *7* to specify a color, or the letter *n* to specify
no color.

The colors are the standard ANSI ones, plus *n*:

*0*
  Black.

*1*
  Red.

*2*
  Green.

*3*
  Yellow (or brown, on some terminals).

*4*
  Blue.

*5*
  Purple (aka violet).

*6*
  Cyan.

*7*
  White.

*n*
  No custom color. Output will be in the terminal's default foreground color.

The order they're used in the *colors* argument is:

**1**
  Commands.

**2**
  Operators.

**3**
  Functions.

**4**
  Constants.

**5**
  Line numbers (at the start of a line only; **GOTO** and **GOSUB** line numbers
  are constants).

**6**
  Variable names.

So, the default color scheme is equivalent to:

  **-c** *32516n*

NOTES
=====

**listbas** will refuse to operate on a LIST-protected program with
scrambled variable names. For code-protected programs, it will stop at
the line with the invalid offset. Use **unprotbas**\(1) to remove the
protection.

**listbas** is similar to Jindroush's **chkbas**\(1). The main differences are:

- **listbas** prints ATASCII graphics as Unicode equivalents, so the listing
  looks very similar to how it would appear on the Atari.

- **listbas** does color syntax highlighting.

- **listbas** only supports Atari BASIC, not Turbo BASIC or BASIC XL/XE.

- **listbas** doesn't show information about the variables. Use **vxrefbas**\(1)
  for that.

- **listbas** will not write ATASCII data to your terminal. By default, it
  converts ATASCII characters into Unicode/UTF-8 characters
  that won't confuse the terminal. When outputting raw ATASCII (**-a** option),
  it refuses to run if standard output is a terminal.

- **listbas** only lists line 32768 (the immediate mode command) if
  specifically asked to do so.

- **listbas** doesn't print a banner on startup.

- **listbas** tells you if the program is protected, and refuses to operate
  on variable-protected programs.

I thought about adding an HTML output option, but there's no need: if you want
a colorful listing of an Atari BASIC program, install **aha**\(1) from
https://github.com/theZiz/aha (or your distro's package repo) and run
something like::

  listbas PROGRAM.BAS | aha > program.html

ENVIRONMENT
===========

**LISTBAS_OPTS**
  If this environment variable is set, **listbas** parses its value as though
  the contents were placed on the command line as options, preceding any actual
  option. Example::

    export LISTBAS_OPTS="-c123456 -d"

  If you place the above line in your shell's startup script, **listbas** will
  use your custom color scheme, and will default to the "dots" output mode. If
  you then run **listbas** the **-c** and/or **-x**, **-m** options, the options
  on the command line will override the environment.

EXIT STATUS
===========

0 for success, 1 if there was an error reading the input (e.g. file
not found), or 2 if the input file has invalid tokens (if this
happens, you will also see a warning about it on stderr).

.. include:: manftr.rst