root/tags/lgt2171/INSTALL

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Logtalk - Object oriented extension to Prolog
Release 2.17.1

Copyright (c) 1998-2004 Paulo Moura.  All Rights Reserved.
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Installing Logtalk is just a matter of decompressing the downloaded 
archive and copying the resulting directory to a suitable location. 
The Logtalk directory can reside in any user accessible location. 
This location depends on the working environment and on the number 
of users. The "misc" sub-directory contains some shell scripts for 
easy installation of Logtalk on Unix and Unix-like operating systems.


INSTALLING FOR A SINGLE USER

In the case of a single user, the Logtalk directory can simply be 
copied to the user home directory.


INSTALLING FOR MULTIPLE USERS

In the case of multiple users, the Logtalk directory can be copied to 
any location that its accessible by all the users.

Regarding directory and file permissions, it is advisable to make all files 
read-only in order to avoid user tempering. However, the library and examples 
sub-directories (and possibly the compiler sub-directory, depending on the 
chosen Prolog compiler) must be user writable as compiling Logtalk source 
files generates intermediate Prolog files, which are written to the same 
location as the source files. However, making directories world-writable is a 
security risk. There are two alternatives. The first one is to pre-compile the 
library and all examples and to turn on the compiler option "smart_compilation" 
in order to avoid the need of recompilation when the files are loaded by the 
users. The second alternative is to copy the Logtalk xml, examples, and library 
directories to each user directory (the "misc" sub-directory contains a shell 
script for automating these copies).


ENVIRONMENT VARIABLES

In Unix and Unix-like systems is recommended that you define an environment 
variable named $LOGTALKHOME pointing to the Logtalk installation for use with 
your Prolog compilers. If you use a csh shell, add the following line to your 
~/.cshrc file:

    setenv LOGTALKHOME "/your/installation/directory/lgt2171"

If you use a bash shell, add the following lines to your ~/.profile file:

    LOGTALKHOME="/your/installation/directory/lgt2171"
    export LOGTALKHOME

When using the provided shell script for installing Logtalk, a symbolic link 
to the Logtalk installation directory is automatically created. The link is 
named "logtalk". In this case, use this symbolic link to define the 
environment variable in order to avoid breaking it when upgrading Logtalk.