2.11.1.5 SWI-Prolog app scripts

As of version 9.1.18, SWI-Prolog allows starting an application using the command below.

swipl [option ...] [path:]name [arg ...]

This command line first processes Prolog options described in section 2.4. Note that most standard Prolog commandline options are not relevant. The -f defaults to none, which implies that the user init file is by default not loaded. If an application wishes to load the user init file, it should load user_app_config(init) if this file exists (see exists_source/1).

Next, it locates path(name) using SWI-Prolog's file search mechanism defined by absolute_file_name/3. After loading this file it finds the last goal registered for main using initialization/2 as described in section 2.11 - if there is no initization directive for main, the program terminates with an error. By default, the application terminates after the entry point terminates. The entry point may enable the interactive Prolog REPL loop by calling cli_enable_development_system/0. Other forms of the initialization/2 directive are also allowed, in addition to‘main`.

All command line options after [path:]name are accessible in the Prolog flag argv.

The optional path defaults to app. By default, apps are searched in the directories below. See file_search_path/2 for details.

1. The app directory of the SWI-Prolog installation
2. User and site configuration. On POSIX systems using the XDG file name conventions, this is normally /.local/share/swi-prolog/app/ and /usr/share/swi-prolog/app.
3. The app directory of a Prolog pack.

The following apps are provided by the installation

app

Print information on installed apps. For example, to list all available apps, run

swipl app list

pack

Command line driven management of Prolog packs. This is a front-end to the Prolog library library(prolog_pack). For example, to find packages related to type, use the command below.

swipl pack find type