swipl

Start an interactive session

$ swipl

$ swipl --quiet -t "[command]"

$ swipl [path/to/file.pl]

$ swipl --dump-runtime-variables

$ swipl --version

swipl [options] [file ...]

-f file
    Load file as a Prolog source file.

-l file
    Consult file. Same as `-f file` but suppresses file existence warnings.

-g goal
    Execute goal after loading files. Goal must be specified as a quoted string.

-t goal
    Top-level goal. Similar to `-g goal`, but used to define the top-level interaction loop. The default top-level is `halt`.

-q
    Suppress informational messages at startup.

-tty
    Force the use of terminal control even if standard input and output are redirected.

-nodebug
    Start without debugging facilities.

-O
    Optimize loaded code.

-s file
    Use file as script. The arguments are passed via the `argv/1` predicate.

--version
    Print the SWI-Prolog version number and exit.

--help
    Print a summary of command-line options and exit.

The `swipl` command starts the SWI-Prolog interactive toplevel shell. This shell allows users to interact with the Prolog system, loading Prolog code, posing queries, and debugging programs. It provides a read-evaluate-print loop (REPL) environment specifically designed for Prolog. `swipl` supports a wide range of command-line options to customize the behavior of the Prolog environment, including loading files, setting flags, and specifying the initial query to execute. It is the primary way to interact with SWI-Prolog from the command line, used extensively for development, testing, and running Prolog applications. The environment provides debugging tools such as tracing and spypoints. The core functionality revolves around the Prolog engine, offering features such as backtracking, unification, and logical inference to execute Prolog programs.

The precise behavior of `swipl` may vary slightly depending on the SWI-Prolog version and the operating system. Error handling and resource management within the Prolog code itself can significantly impact the stability and performance of the system.

When `swipl` starts, it looks for initialization files. These files are automatically loaded and can be used to customize the Prolog environment, e.g., by defining commonly used predicates or setting up libraries. The location and names of these files depend on the system. Usually there are some files like `.swiplrc` or `init.pl`. Consult the SWI-Prolog documentation for specific details.

Several environment variables can influence the behavior of `swipl`. For example, `SWI_HOME_DIR` can be used to specify the location of the SWI-Prolog installation directory.

The `swipl` command returns an exit code. A return code of 0 typically indicates success, while non-zero values indicate errors. The specific meaning of non-zero exit codes is documented in the SWI-Prolog reference manual. The return value may reflect if loading a file results in an error, the execution goal fails, or some other error occurs during start up or shutdown.

SWI-Prolog was originally developed by Jan Wielemaker at the University of Amsterdam. It has evolved over several decades, becoming a widely used open-source Prolog implementation. The `swipl` command has been the primary entry point for interacting with SWI-Prolog since its early versions. Its design emphasizes portability, extensibility, and integration with other programming languages.

plunit(1), pldoc(1)