Post Installation Setup
=======================

by Leslie S. Satenstein

1.0   Introduction
==================
Following the execution of GNU-APL's "make install" (which is conceptually
performed by a system administrator with access permissions to directories like
/etc or /usr/), some additional setup activities by the user are normally
required. The user can try out GNU APL before this additional setup, but some
APL commands such as )SAVE will not work because the creation and specification
of directories that are used for storing files created by the user are the
responsibility of the user and not of the system administrator. 

The description below assumes that ./configure of GNU APL was executed without
a prefix= option. If the prefix option was used then some of the paths further
down in this document may differ accordingly.

The "make install" procedure should have created a directory

        /usr/local/etc/gnu-apl.d 
        
        or

        /etc/gnu-apl.d 


This directory contains:

        keyboard1.txt           a default USA PC104 keyboard layout
        parallel_thresholds     a presentation settings for apl  multitasking 
        preferences             a file to tailor apl for your system

This next section describes configuring GNU-APL using the preferences file.
The preference file comes pre-configured, but in some instances, the 
global contents may not suit your requirements. Examples include the need to
maintain a private copy of some workspaces or modify some apl actions.

In this situation you may choose to create a sub-directory with a copy of the
above directory contents in your home directory. If so, then the name of that
directory should be $(HOME)/.config/gnu-apl/. The easiest way to create
this sub-directory and its initial content is the shell command:

    cp -dR /etc/gnu-apl.d $HOME/.config/gnu-apl

The command may be somewhat different, for example if you used non-default
directories in your ./configure command.

       
1.1   KEYBOARDS
===============
There are two physical keyboards predominately in use. One is the popular
American keyboard layout, model pc104, shown below as Keyboard1.txt:

PC104 USA Standard Keyboard:
===========================
╔════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦═════════╗
║ ~  ║ !⌶ ║ @⍫ ║ #⍒ ║ $⍋ ║ %⌽ ║ ^⍉ ║ &⊖ ║ *⍟ ║ (⍱ ║ )⍲ ║ _! ║ +⌹ ║         ║
║ `◊ ║ 1¨ ║ 2¯ ║ 3< ║ 4≤ ║ 5= ║ 6≥ ║ 7> ║ 8≠ ║ 9∨ ║ 0∧ ║ -× ║ =÷ ║ BACKSP  ║
╠════╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦══════╣
║       ║ Q  ║ W⍹ ║ E⍷ ║ R  ║ T⍨ ║ Y¥ ║ U  ║ I⍸ ║ O⍥ ║ P⍣ ║ {⍞ ║ }⍬ ║  |⊣  ║
║  TAB  ║ q? ║ w⍵ ║ e∈ ║ r⍴ ║ t∼ ║ y↑ ║ u↓ ║ i⍳ ║ o○ ║ p⋆ ║ [← ║ ]→ ║  \⊢  ║
╠═══════╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩══════╣
║ (CAPS   ║ A⍶ ║ S« ║ D» ║ F  ║ G  ║ H  ║ J⍤ ║ K  ║ L⌷ ║ :≡ ║ "≢ ║         ║
║  LOCK)  ║ a⍺ ║ s⌈ ║ d⌊ ║ f_ ║ g∇ ║ h∆ ║ j∘ ║ kλ ║ l⎕ ║ ;⍎ ║ '⍕ ║ RETURN  ║
╠═════════╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═════════╣
║             ║ Z  ║ Xχ ║ C¢ ║ V  ║ B£ ║ N  ║ Mμ ║ <⍪ ║ >⍙ ║ ?⍠ ║          ║
║  SHIFT      ║ z⊂ ║ x⊃ ║ c∩ ║ v∪ ║ b⊥ ║ n⊤ ║ m| ║ ,⍝ ║ .⍀ ║ /⌿ ║  SHIFT   ║
╚═════════════╩════╩════╩════╩════╩════╩════╩════╩════╩════╩════╩══════════╝

The second physical layout, based on the international keyboard layout pc105 
is the following, shown as keyboard2.txt 

PC105 International standard Keyboard
=====================================
╔════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════╦════════════╗
║ ~  ║ !⌶ ║ @⍫ ║ #⍒ ║ $⍋ ║ %⌽ ║ ^⍉ ║ &⊖ ║ *⍟ ║ (⍱ ║ )⍲ ║ _! ║ +⌹ ║            ║
║ `◊ ║ 1¨ ║ 2¯ ║ 3< ║ 4≤ ║ 5= ║ 6≥ ║ 7> ║ 8≠ ║ 9∨ ║ 0∧ ║ -× ║ =÷ ║ BACKSP     ║
╠════╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═╩══╦═════════╣
║       ║ Q  ║ W⍹ ║ E⍷ ║ R  ║ T⍨ ║ Y¥ ║ U  ║ I⍸ ║ O⍥ ║ P⍣ ║ {⍞ ║ }⍬ ║         ║
║  TAB  ║ q? ║ w⍵ ║ e∈ ║ r⍴ ║ t∼ ║ y↑ ║ u↓ ║ i⍳ ║ o○ ║ p⋆ ║ [← ║ ]→ ║ RETURN  ║
╠═══════╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╦══╩═╗       ║
║ (CAPS   ║ A⍶ ║ S  ║ D  ║ F  ║ G  ║ H  ║ J⍤ ║ K⌸ ║ L⌷ ║ :≡ ║ "≢ ║ |⊣ ║       ║
║  LOCK)  ║ a⍺ ║ s⌈ ║ d⌊ ║ f_ ║ g∇ ║ h∆ ║ j∘ ║ k' ║ l⎕ ║ ;⍎ ║ '⍕ ║ \⊢ ║       ║
╠════════╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩═══╦╩════╩═══════╣
║        ║ < ¦║ Z  ║ Xχ ║ C¢ ║ V  ║ B£ ║ N  ║ M  ║ <⍪ ║ >⍙ ║ ?⍠ ║             ║
║  SHIFT ║ > °║ z⊂ ║ x⊃ ║ c∩ ║ v∪ ║ b⊥ ║ n⊤ ║ m| ║ ,⍝ ║ .⍀ ║ /⌿ ║  SHIFT      ║
╚════════╩════╩════╩════╩════╩════╩════╩════╩════╩════╩════╩════╩═════════════╝

The 'preference' file will have a parameter setting to select one or the other
layout. More about this later.  


2.0 The preferences file(s)
===========================

2.1  Introduction
=================
The 'preferences' file contains parameter settings that control the behavior
of the GNU APL interpreter. Most of the settings can also be controlled by
corresponding command line options, but for most settings it is more convenient
to specify them once in one of the preferences files than by command line
options in every invocation of GNU APL.

The settings will allow you to:
 
    o   set text and background colors, 
    o   assign directories and workspace locations, 
    o   location of logs and history file(s), and 
    o   other operational parameters.


The 'preferences' file should reside:

 (1) in directory gnu-apl.d of the system configuration directory. or
 (2) in directory .config/gnu-apl in the user's home directory.
 (3) in both mentioned directories (see below)

In both cases the configuration file name within each must be 'preferences'

The system configuration directory for GNU/Linux is usually /usr/local/etc/ 
or /etc. During the setup of GNU-APL (refer to README-2-configuration) you
have the opportunity to choose a different location. It can be overridden
at compile time by:

  (a)  ./configure --sysconfdir=somewhere-else
  (b)  ./configure --sysconfdir=/home/(your_username)/.config/gnu-apl 


2.2 Local version of preferences.
=================================
To create your own preference file, create the following directory.

     /home/(your_username)/.config/gnu-apl 

copy the system installed /usr/local/etc/gnu-apl.d to

     /home/your_username)/.config/gnu-apl 


If both your own preferences file and the "gnu-apl.d" are present in their
respective directories then the local copy overrides the settings common
to both files.
 
Command line options take precedence over settings made in either of these
files.

The initial content of this 'preferences' file contains a commented list of
all possible settings. You should not remove parameter setting lines but
rather comment or uncomment them.

The balance of this README-9 file describes the parameter setting for GNU-APL.

3.0   WELCOME MESSAGE
=====================
By default GNU-APL displays a welcome message on start-up. 
Usually you will set it once and forget about it.

The corresponding command line option for no welcome message is --silent.

The default setting in the preferences file(s) is:
#
  Welcome       Yes     (default)
# Welcome       No      
#


3.1   OUTPUT COLORING
======================
The default GNU-APL configuration as delivered, is tailored for terminals
displaying a white background. The background colors that APL will use can be
overridden. 

There are options to switch to black background, to no colors, 
or even to allow coloring of GNU-APL displayed output.

Output coloring will cause problems when, for example:

 (a) you run GNU-APL as script
 (b) you use a black background
 (c) you run GNU-APL from emacs
 (d) you run GNU-APL from a different terminal than color xterm

In case (a) you should use the --script command line option and
leave the default Color setting (see #2 below).

In cases (b), (c), and (d) you can uncomment the 'Color No' line below.
This only affects the initial state of output coloring; you can
re-enable colors later with APL command ]XTERM ON.

The corresponding command line options are --Color and --noColor

If your terminal does not understand the ANSI escape sequences, or if you
prefer not to provide escape sequences, then you can set the color
parameter to CURSES and set color numbers to escape sequences as shown
below. This setting requires that certain environment variables (e.g. TERM)
are set properly and that your system's terminfo database contains correct
terminal type definitions for your choice.

The default setting in the preferences file(s) is:
#
  Color         ANSI (default)
# Color         CURSES
# Color         No
#

 
After starting APL you may want to disable coloring initially, but switch 
to curses (the command ]COLOR can be given later on). You can enter the 
color command twice: 

        ]color
        ]COLOR ON
        ]color off
        ]color
        ]COLOR/XTERM OFF


3.2  GNU-APL Terminal handling
==============================
GNU-APL has one input and 4 output channels called CIN, COUT, CERR, and UERR

 -  CIN  is the input channel and output. It echos the input typed by the user, 
 -  COUT is the normal output of the APL interpreter,
 -  CERR is additional error information, in particular logging.
 -  UERR is output of the APL interpreter containing error messages,

CIN, COUT, and UERR write to default stdout while CERR writes to stderr.
Normally stdout and stderr are both displayed on the same terminal,
but output redirection as shown can make a difference. An example
of CERR redirection is:

           apl 2>MyErrorLog.txt 


When the interpreter changes from one output channel to another, for
instance from CIN to COUT after the user has entered a line, then an
escape sequence (actually, any short sequence of characters) is sent
to the real output channel (i,e. stdout or stderr). The new channel
determines which sequence is sent:

 -  CIN:   CIN-SEQUENCE  CLEAR-EOL
 -  COUT:  COUT-SEQUENCE CLEAR-EOL
 -  CERR:  CERR-SEQUENCE CLEAR-EOL
 - UCERR:  UERR-SEQUENCE CLEAR-EOL


3.3   OUTPUT COLOR ESCAPE SEQUENCES FOR ANSI TERMINALS
======================================================

Output coloring is implemented as described below, 
When the interpreter exits, then the sequence

        RESET-SEQUENCE CLEAR-EOL

is sent to the terminal to cause it to set its the display colors 
to their initial state.

The reason for sending CLEAR-EOL (i.e. clear to end of line) is to color
the entire next line not only the chars printed on the next line.

Unfortunately it is difficult, if not impossible, to read the current
color setting from the terminal. Therefore the following is assumed:

GNU-APL is started in a color xterm with white background".

Color xterm is a VT100 (or ANSI) compatible terminal emulation.
If this assumption is correct, then everything should be fine. Otherwise
you may want to change the escape sequence sent to the terminal. 

The numbers below are the hexadecimal values of the bytes sent to the
terminal; 27 (hexadecimal 1b) is the escape character, for example. To
change some or all sequences, uncomment the corresponding line and change
the hex numbers (most likely the columns background and foreground).
Each sequence can be up to 20 characters long. By the way // refers to
the start of comments placed to the right of the terminal control
sequence. The octothorpe (#) is the character placed at the left margin.

The default setting in the preferences file(s) is:
#
#               VT100:          foreground        background
#                               color    |        |    color
#                                        V        V 
# //                    ESC  [  0  ;  3 fg  ;  4 bg  m
# CIN-SEQUENCE           1b 5b 30 3b 33 30 3b 34 37 6d    // ESC [0;30;47m
# COUT-SEQUENCE          1b 5b 30 3b 33 30 3b 34 38 6d    // ESC [0;30;48m
# CERR-SEQUENCE          1b 5b 30 3b 33 35 3b 34 38 6d    // ESC [0;35;48m
# UERR-SEQUENCE          1b 5b 30 3b 33 35 3b 34 38 6d    // ESC [0;35;48m
# RESET-SEQUENCE         1b 5b 30 3b 33 39 3b 34 39 6d    // ESC [0;39;49m
# CLEAR-EOL-SEQUENCE     1b 5b 4B                         // ESC [K
# CLEAR-EOS-SEQUENCE     1b 5b 4A                         // ESC [J
#
# On a black background (still assuming VT100 so that the CLEAR-EOL-SEQUENCE
# does not need to be re-defined), the following may be more suitable:
#
# CIN-SEQUENCE           1b 5b 30 3b 33 32 3b 34 30 6d    // ESC [0;32;40m
# COUT-SEQUENCE          1b 5b 30 3b 33 37 3b 34 30 6d    // ESC [0;37;40m
# CERR-SEQUENCE          1b 5b 30 3b 33 31 3b 34 30 6d    // ESC [0;31;40m
# UERR-SEQUENCE          1b 5b 30 3b 33 31 3b 34 30 6d    // ESC [0;31;40m
# RESET-SEQUENCE         1b 5b 30 3b 33 37 3b 34 30 6d    // ESC [0;37;48m
#

Since all lines are commented out, the ESC sequences assumed by the interpreter
are used. The lines are only shown as a template for the ESC sequences of the
actual terminal.


3.4   OUTPUT COLOR NUMBER FOR CURSES
====================================
There is second way of specifying colors that uses the curses library.
Instead of specifying the escape sequences sent to the terminal you
only need to specify the colors wanted and curses will provide the escape
sequences needed.

The default setting in the preferences file(s) is:
# Numbers for colors seem to be (nota bene: the author is color-blind):
#
# 0: black
# 1: blue
# 2: green
# 3: cyan
# 4: red
# 5: magenta
# 6: yellow
# 7: white
#
# The colors are specified as numbers like this:
#
# CIN-FOREGROUND  0
# CIN-BACKGROUND  7
# COUT-FOREGROUND 2
# COUT-BACKGROUND 7
# CERR-FOREGROUND 5
# CERR-BACKGROUND 8
# UERR-FOREGROUND 5
# UERR-BACKGROUND 8
#
# or, for dark background:
#
# CIN-FOREGROUND  2
# CIN-BACKGROUND  0
# COUT-FOREGROUND 7
# COUT-BACKGROUND 0
# CERR-FOREGROUND 5
# CERR-BACKGROUND 0
# UERR-FOREGROUND 5
# UERR-BACKGROUND 0
#

Do not mix the two methods (escape sequences vs. color numbers).
If they are mixed then the last entry processed in this file determines
which method will be used. Also, the numbers for colors are different
in each method.


3.5   INPUT ESC SEQUENCES
=========================

Below is a brief explanation of how you can configure the ESC (escape or
other) sequence sent by the terminal's cursor-up, cursor-down, cursor-left,
cursor-right, Home, End, Ins, and Del keys. 

The sequences can be set explicitly (in the following) or via CURSES
The latter (CURSES) may fail to work because the sequences reported by
CURSES may be different from the sequences sent by the keyboard.

The default setting in the preferences file(s) is:
#
  Keyboard      NOCURSES (default)
# Keyboard      CURSES
#
# KEY-CURSOR-UP          1b 5b 41
# KEY-CURSOR-DOWN        1b 5b 42
# KEY-CURSOR-RIGHT       1b 5b 43
# KEY-CURSOR-LEFT        1b 5b 44
# KEY-CURSOR-END         1b 5b 46
# KEY-CURSOR-HOME        1b 5b 48
# KEY-INSMODE            1b 5b 32 7e
# KEY-DELETE             1b 5b 33 7e
#


3.6   SHARED VARIABLES
======================
Shared variables are perhaps a feature with which you may not be familiar.
To work with certain software packages on the host computer, your program
must follow a discipline. The variables involved with this discipline are
listed below.

Shared variables are represented by: 
Offer to share var.    (⎕SVO), 
shared var. Retraction (⎕SVR),
shared var. Control    (⎕SVC),
shared var. Query      (⎕SVQ),    
shared var. State      (⎕SVS) 

Using 'Shared variables' starts (forks) an independent helper process
(APserver) to communicate with other APL processors. 

If you do not need all the above functions then you can (and should) prevent
accidental starting of the APserver by setting SharedVars to Disabled. If
SharedVars are disabled then GNU APL starts a little faster and, of course,
⎕SVO and friends won't work.

The default setting in the preferences file(s) is:
# The corresponding command line options are --SV and --noSV
#
  SharedVars    Enabled     (default)
# SharedVars    Disabled


3.7   LOGGING FACILITIES
=========================
By default, dynamic logging is disabled and the following settings have no
effect.

Logging is a facility that is occasionally used for debugging purposes. As
a regular user, you should have no requirement to make use of dynamic logging.

To enable dynamic logging, you must recompile the interpreter, specifying
dynamic logging. The following three steps are required. 

  ./configure DYNAMIC_LOG_WANTED=yes <... other configure options>
  make
  make install (or try: src/apl)

Otherwise you can specify the Logging facilities (numbered 1-43 or more)
that can be enabled when the APL interpreter starts, This option can
be used several times.

Checkout the GNU-APL command ]LOG for available logging facilities

The corresponding command line option is -l <num>

 Logging 1
 Logging 2
 ...
 Logging 37


3.7    APL LIBRARIES
====================

GNU-APL uses library numbers from 0 to 9 in commands )LOAD, )SAVE, and )COPY,
library 0, if enabled (see below) refers to our own collection of apl
workspaces.
 
For 
example 1:

 )LOAD 1 workspace

example 2:
  Interpreter commands )IN and )OUT use library number 0 implicitly;
  )LOAD, )SAVE, and )COPY use library number 0 implicitly when no
  library number is given.

WARNING: Each library (directory) assigned to LIBREF-0 must be unshared and
unique. 

For example, issuing the ")CONTINUE" command, results in storing the CONTINUE 
workspace therein. Storing CONTINUE will overwrite the previous one. Sharing 
the default LIBREF-0 library among different users will be likely to have 
very undesirable effects. 

Within the preferences file, the directories corresponding to the library
numbers can be configured as shown below.

Library numbers 3, 4, and 5 are used (and often overwritten!) to store
libraries that are shipped with GNU APL. )SAVEing or )DUMPing workspaces into
these directories is therefore a bad idea.

If GNU APL is used by different programmers on the same machine, then the
following scheme for library reference numbers is recommended:

0  for workspaces that are only accessible by one user (or, in GNU/Linux terms,
   by the owner of the file), This directory typically exists somewhere below
   $HOME.

1  for workspaces that are only accessible by the group (normally the GNU/Linux
   group to which the user belongs).

2  for workspaces that are readable by every user on the machine.

In other words: the library numbers 0, 1, and 2 correspond to the 'owner',
'group', and 'all' permissions of the files respectively. However, GNU-APL
does not set these permissions based on the library numbers (because all
this is only a recommended convention) and the users or group members
are responsible for setting permissions on workspace files or directories.

For GNU/Linux machines that are only used by a single user, the user may
set up the directories libraries 0-2 and 6-9 as needed.

The default setting in the preferences file(s) reflects the above scheme 
(although commented out) and only sets up the directories for libraries that
are installed by GNU APL itself. For example (details may vary due to
./configure options):
#
# LIBREF-0 /home/xyz/my-own-libs
# LIBREF-1 /home/xyz/my-group-libs
# LIBREF-2 /group/abc/other-libs
  LIBREF-3 /usr/local/lib/apl/wslib3
  LIBREF-4 /usr/local/lib/apl/wslib4
  LIBREF-5 /usr/local/lib/apl/wslib5
# LIBREF-6 /usr/lib/gnu-apl/lib-6
# LIBREF-7 /usr/lib/gnu-apl/lib-7
# LIBREF-8 /usr/lib/gnu-apl/lib-8
# LIBREF-9 /usr/lib/gnu-apl/lib-9
#

3.8   READLINE HISTORY PARAMETERS
=================================

GNU APL can provide a history of lines entered by the user in immediate
execution mode and ∇-edit mode.

As shown below, the number of history lines and the location of the history
file can be configured. Some users prefer to have only one history file (and
in that case $HOME/.config/gnu-apl/apl.history might be a suitable file name).

Other users prefer to have a history file in the current directory so that
they can work in different APL projects in parallel and have separate
histories, one for each project. In that case, .apl.history is a better
choice for the file name, because the file is hidden and relative. This is
also the default in the preferences file(s):

READLINE_HISTORY_LEN  500
READLINE_HISTORY_PATH .apl.history

The history can serve two purposes: to recall lines that were previously
entered and to list what was recently done (with the apl )HISTORY command).
For the latter purpose it is normally convenient to show the new ⎕CR of a
function that was edited instead of the command that started the editor.
The following parameter controls whether the editor command (like ∇foo )
or the new ⎕CR of the function shall be inserted into the history.


3.9   EDITOR OPTIONS
====================
GNU-APL comes with a built-in editor. The following setting controls which
of the lines that were entered in function editing mode are being inserted
into the history.

The 'Always' setting restores the edited function regardless of its current
state. The 'Never' setting is useful for automated test scripts because it
avoids redundancy in the log files produced.

The default (modified) is a compromise that inserts only the editor
command if the function was opened but not changed (e.g. ∇FOO[⎕]∇ )
and the entire new ⎕CR if the function was changed or (newly created).
With that setting, one can cut-and-paste from a history file into an
interactive session to 'redo' a function modification. 

The default setting in the preferences file(s) is:
#
# NABLA-TO-HISTORY  Never
  NABLA-TO-HISTORY  Modified (default)
# NABLA-TO-HISTORY  Always
#


3.10   BACKUP OPERATIONS
========================
In general, if one is modifying a workspace, it is best to load it and
immediately resave it under a new name. The GNU-APL options available are to
create a backup before a )SAVE or )DUMP WORKSPACE command. The workspace
created by )CONTINUE is saved, but not backed up.

The default setting in the preferences file(s) is:
#
BACKUP_BEFORE_SAVE  yes
#

To recover a backup workspace (refer to the LIBREF-0 option chosen),
change to the directory indicated. Therein you will see the workspace
you were using and the same workspace with a .bak appended. Example:
consider a recovery action for the 'meta' workspace In the directory
referred to by LIBREF-0 you would note:

    meta.xml   meta.xml.bak

For example, delete the meta.xml or rename it to something else. 
Restore the original meta.xml (rename the meta.xml.bak to meta.xml).


3.11    KEYBOARD LAYOUT 
=======================
GNU APL assumes a particular layout of your keyboard (and assumes that you
do your best to obtain that layout). That assumed layout is shown when you
give the ]KEYB command.

If your physical keyboard layout differs from the assumed keyboard for some
reason, then the ]KEYB command will show the wrong layout. You can correct
this difference providing your own keyboard file which (when specified) is
shown by the

     ]KEYB command instead of the assumed layout.

You can choose between one of the files called 'keyboard1.txt' or
keyboard2.txt. If your computer has a different keyboard layout, you may
create your own version as keyboard.txt and revise the parameter as shown in
the following:

#
# KEYBOARD_LAYOUT_FILE  /etc/gnu-apl.d/keyboard1.txt
#

12.0  Abnormal Termination
==========================

Normally you exit GNU APL by issuing the command )OFF. Hitting ^D
(aka. end-of-input) once can be used to end the execution of most other
programs, but has no effect in GNU APL.

You can make GNU APL exit after a number of consecutive ^Ds by specifying
a (small) positive number as shown below: Note that the interpreter will
always exit if a large number of ^Ds (or EOFs) are read-in in rapid
succession. NB: ^Ds may exist within a script and need not be entered via
the keyboard. Setting the value to zero establishes the system default. 

#CONTROL-Ds-TO-EXIT 7
 CONTROL-Ds-TO-EXIT 0

13.0    Default Print Width
===========================

GNU-APL defaults the ⎕PW to 80

If the terminal that you normally use has fewer or more columns, then you
may want to specify a different initial value for ⎕PW below. A further option
is the Windows Change (WINCH setting).

With the WINCH-Setting option, on startup you can cause the Window Change
(WINCH) signal (which is sent, for example, if the size of a window is changed)
to set ⎕PW to the terminal width setting contained in the WINCH signal.

The intended effect is that re-sizing of the terminal window will cause GNU-APL
to adapt itself to the new window size. This appears to work on GNU/Linux but
may not work on other platforms! USE AT YOUR OWN RISK.

# INITIAL-⎕PW 80
# WINCH-SETS-⎕PW  Yes


14.0  Security Settings
=======================

Under certain circumstances, for example if GNU APL is used as a CGI script
for publicly accessible web pages, it may be desireable to disable certain
capabilities that could otherwise be abused to access system resources via
the GNU APL capabilities.

The following lines show examples of GNU APL capabilities that can be
disabled. The security settings are put into profile [1] which means that
they only have an effect if:

 (1) GNU APL was ./configured with SECURITY_LEVEL_WANTED=1, and
 (2) the profile (i.e the -p command line option) with which GNU APL was
     started matches the profile for which the setting was made (if any)

If a disabled capability is being used then it will throw a DOMAIN_ERROR
and the )MORE command will indicate a security violation. For example:

#
Profile 1
  disable_Quad_SQL          yes    # disable ⎕SQL
  disable_Quad_FIO          no     # do not disable ⎕FIO
  disable_native_functions  yes    # disable A ⎕FX B (native fnctions)

