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This file is part of Logtalk
Copyright 1998-2021 Paulo Moura
SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.


The recommended way of installing Logtalk is to use, whenever possible, one of the provided installers that can be downloaded from the Logtalk website. Installers are provided for macOS, Windows, and Linux.

This file contains detailed instructions for manual installation and configuration of Logtalk. You should also consult the scripts/ and integration/ files for a description of a set of shell scripts that might be used for Logtalk installation on some operating-systems and for easy Logtalk integration with popular Prolog compilers.

The POSIX shell scripts assume that bash is available.

Logtalk basic installation

Manual installation of Logtalk can be accomplished by decompressing the sources archive (or by cloning the development git server), optionally running an installation script, and defining a couple of environment variables. You can install Logtalk in any user accessible location. Whenever possible, it is recommended that Logtalk be installed by a user with administrative rights, as described below. This leads to a setup where each Logtalk user may freely run and modify the provided examples, library, and tool files with the option of, at any time, restoring the files to its original state by simply running one of the provided scripts.

Using the sources or git clone directory

In this case, there is no installation procedure other than decompressing the sources (or cloning the git repository) into a convenient directory. Simply skip to the section below on setting the Logtalk environment variables and use the directory full path as the value for both the LOGTALKHOME and LOGTALKUSER variables. Note that in this case, on POSIX systems, you will need to call the provided scripts without omitting the .sh extension (e.g. instead of swilgt).

Installing for a single user with no administrative rights

If you want to keep a pristine copy of the sources (or avoid possible merge conflicts when updating your git clone) use the provided installation script to copy the files that typically you want to play with and modify elsewhere.

For POSIX systems (macOS, Linux, ...), first, open a terminal, change the current directory to the Logtalk directory, and then type:

% cd scripts
% ./ -p $HOME

This will install Logtalk into the $HOME/share and $HOME/bin directories (the $HOME/bin path must be in your PATH environment variable; also, the $HOME/share/man directory should be in your MANPATH environment variable).

If you're using Windows, you can simply use the provided installer (which supports both admin and non-admin users) to perform a full installation. The Windows installer is built using Inno Setup, which is freely available. If you need to customize the installer (e.g. to recognize Prolog compilers installed in non-standard locations), edit the Inno Setup script found on the scripts/windows directory and regenerate the installer.

Installing for one or more users by a user with administrative rights

For POSIX systems, first, open a terminal, change the current directory to the Logtalk directory, and then type:

% cd scripts
% sudo ./

This installation script makes all files read-only for non-admin users in order to avoid user tampering. This is a convenient setup for computer labs, given that making directories world-writable is a security risk. The installation script accepts an installation prefix as argument. For example:

% sudo ./ -p /opt/local

If no prefix is given, the default installation prefix depends on the operating-system:

  • macOS: /opt/local
  • Debian distributions: /usr
  • Other POSIX systems: /usr/local

The script installs Logtalk in the $prefix/share directory with Prolog integration and other useful shell scripts written to the $prefix/bin directory, which should be in your PATH environment variable. The script also creates a symbolic link, $prefix/share/logtalk, which can be used for e.g. defining the LOGTALKHOME environment variable described below. Man pages are installed on the $prefix/share/man directory, which should be in your MANPATH environment variable.

If you're using Windows, you can simply use the provided GUI installer (which supports both admin and non-admin users) to perform a full installation. You can also easily generate the GUI installer yourself. See the instructions on the scripts/windows/ file. If the installer fails to detect the installation of the backend Prolog compiler you want to use, you can manually create a Windows integration shortcut by finding the full path to the Prolog executable and using the Prolog specific command-line options to load the integration file (see the Bash integration scripts in the integration directory for the options and file to be loaded). For example assume that you're using a non-standard and non-default installation of SWI-Prolog in a removable disk mounted as G:\. The shortcut would use a path such as:

G:\swipl\bin\swipl-win.exe -s "%LOGTALKHOME%\integration\"

Alternatively, on Windows 10 or Windows Server 2019, you can use the Windows Subsystem for Linux (WSL) and install Logtalk using one of the Linux installers or by following the instructions above for POSIX systems.

Setting Logtalk environment variables

You need to set two environment variables, LOGTALKHOME and LOGTALKUSER. The environment variable LOGTALKHOME should be set to the Logtalk installation directory. The environment variable LOGTALKUSER should point to a directory in your home directory where you want to store the user-specific Logtalk files (by default, $HOME/logtalk on POSIX systems and My Documents\Logtalk on Windows). Both environment variables may be set for all users by a user with administration privileges.

For POSIX systems using a bash shell, edit and add the following lines to your ~/.profile file:

export LOGTALKHOME=/your/logtalk/installation/directory
export LOGTALKUSER=$HOME/logtalk

In case you're using the clone directory itself to run Logtalk without running the script, you will also need to add:


If you use instead a csh shell, edit and add the following lines to your ~/.cshrc file:

setenv LOGTALKHOME /your/logtalk/installation/directory
setenv LOGTALKUSER "${HOME}"/logtalk

In case you're using the clone directory itself to run Logtalk without running the script, you will also need to add:

setenv PATH "${PATH}":"${LOGTALKHOME}"/tools/diagrams
setenv PATH "${PATH}":"${LOGTALKHOME}"/tools/lgtdoc/xml
setenv PATH "${PATH}":"${LOGTALKHOME}"/scripts
setenv PATH "${PATH}":"${LOGTALKHOME}"/integration

Don't use relative paths such as ../ or ./ in the definition of the environment variables. Some Prolog compilers don't expand environment variables, resulting in file not found errors when attempting to use the Logtalk integration scripts.

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, you may use this symbolic link to define the LOGTALKHOME environment variable in order to avoid breaking it when upgrading Logtalk.

If you're using Windows, the provided GUI installer (which supports both admin and non-admin users) takes care of the definition of the environment variables.

End-user setup

Skip this step if you have set both Logtalk environment variables (LOGTALKHOME and LOGTALKUSER) to point to the same directory.

Each user must make a local copy of the Logtalk user-modifiable files (examples, libraries, tools, and other supporting files) in his/her home directory. These copies can be easily made by running the logtalk_user_setup shell script (see the scripts/ file for details):

  • POSIX systems
    % logtalk_user_setup
  • Windows
    C:\> logtalk_user_setup

The local copies made by the logtalk_user_setup scripts have both read and write permissions for the user running the script. When used with one of the backend Prolog compilers for which an integration script is provided on the integration directory, this setup as the advantage of allowing each end-user to independently customize default compilation flags, library paths, and modify and experiment with the provided libraries and examples.

Windows (admin and non-admin) users may also use the Logtalk GUI installer to setup their Logtalk user folder and the LOGTALKUSER environment variable.

User applications should preferable be kept outside of the Logtalk user folder created by the scripts above as updating Logtalk often results in updating the contents of this folder. If your applications depend on customization of the distribution files, backup those changes before updating Logtalk (the scripts above automatically make a backup of any existing Logtalk user folder but you should rely on your own backups).

Automatically loading Logtalk at Prolog startup

The $LOGTALKHOME/integration sub-directory contains shell scripts for running Logtalk with all supported backend Prolog compilers. You can use these scripts as examples when creating initialization files for other Prolog compilers. Be sure to read the adapters/ file notes on the Prolog compilers that you intend to use.

There's also a logtalk_backend_select script that creates a logtalk alias to the Prolog integration script of your choice.

Customizing Logtalk

Please see the file for details on how to customize your Logtalk installation and working environment.