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Getting started on Un*x-like machines

Author(s): M.Hermenegildo.

Version: 1.10#6 (2004/8/7, 21:46:39 CEST)

Version of last change: 1.7#133 (2001/11/1, 16:34:6 CET)

This part guides you through some very basic first steps with Ciao on a Un*x-like system. It assumes that Ciao is already installed correctly on your Un*x system. If this is not the case, then follow the instructions in section Installing Ciao from the source distribution first.

We start with by describing the basics of using Ciao from a normal command shell such as sh/bash, csh/tcsh, etc. We strongly recommend reading also section An introduction to the Ciao emacs environment (Un*x) for the basics on using Ciao under emacs, which is a much simpler and much more powerful way of developing Ciao programs, and has the advantage of offering an almost identical environment under Un*x and Windows.

Testing your Ciao Un*x installation

It is a good idea to start by performing some tests to check that Ciao is installed correctly on your system (these are the same tests that you are instructed to do during installation, so you can obviously skip them if you have done them already at that time). If any of these tests do not succeed either your environment variables are not set properly (see section Un*x user setup for how to fix this):

Also, the following documentation-related actions should work:

Un*x user setup

If the tests above have succeeded, the system is probably installed correctly and your environment variables have been set already. In that case you can skip to the next section.

Otherwise, if you have not already done so, make the following modifications in your startup scripts, so that these files are used (<LIBROOT> must be replaced with the appropriate value, i.e., where the Ciao library is installed):

If after following these steps things do not work properly, then the installation was probably not completed properly and you may want to try reinstalling the system.

Using Ciao from a Un*x command shell

Starting/exiting the top-level shell (Un*x)

The basic methods for starting/exiting the top-level shell have been discussed above. If upon typing ciao you get a "command not found" error or you get a longer message from Ciao before starting, it means that either Ciao was not installed correctly or you environment variables are not set up properly. Follow the instructions on the message printed by Ciao or refer to the installation instructions regarding user-setup for details.

Getting help (Un*x)

The basic methods for accessing the manual on-line have also been discussed above. Use the table of contents and the indices of predicates, libraries, concepts, etc. to find what you are looking for. Context-sensitive help is available within the emacs environment (see below).

Compiling and running programs (Un*x)

Once the shell is started, you can compile and execute Prolog modules inside the interactive top-level shell in the standard way. E.g., type use_module(file)., use_module(library(file)). for library modules, ensure_loaded(file). for files which are not modules, and use_package(file). for library packages (these are syntactic/semantic packages that extend the Ciao Prolog language in many different ways). Note that the use of compile/1 and consult/1 is discouraged in Ciao.

For example, you may want to type use_package(iso) to ensure Ciao has loaded all the ISO builtins (whether this is done by default or not depends on your .ciaorc file). Do not worry about any "module already in executable" messages --these are normal and simply mean that a certain module is already pre-loaded in the top-level shell. At this point, typing write(hello). should work.

Note that some predicates that may be built-ins in other Prologs are available through libraries in Ciao. This facilitates making small executables.

To change the working directory to, say, the examples directory in the Ciao root directory, first do:

      ?- use_module(library(system)).

(loading the system library makes a number of system-related predicates such as cd/1 accessible) and then:

      ?- cd('$/examples').  

(in Ciao the sequence $/ at the beginning of a path name is replaced by the path of the Ciao root directory).

For more information see section The interactive top-level shell.

Generating executables (Un*x)

Executables can be generated from the top-level shell (using make_exec/2) or using the standalone compiler ( ciaoc). To be able to make an executable, the file should define the predicate main/1 (or main/0), which will be called upon startup (see the corresponding manual section for details). In its simplest use, given a top-level foo.pl file for an application, the compilation process produces an executable foo, automatically detecting which other files used by foo.pl need recompilation.

For example, within the examples directory, you can type:

    ?- make_exec(hw,_).

which should produce an executable. Typing hw in a shell (or double-clicking on the icon from a graphical window) should execute it.

For more information see section The interactive top-level shell and section The stand-alone command-line compiler.

Running Ciao scripts (Un*x)

Ciao allows writing Prolog scripts. These are files containing Prolog source but which get executed without having to explicitly compile them (in the same way as, e.g., .bat files or programs in scripting languages). As an example, you can run the file hw in the examples directory of the Ciao distribution and look at the source with an editor. You can try changing the Hello world message and running the program again (no need to recompile!).

As you can see, the file should define the predicate main/1 (not main/0), which will be called upon startup. The two header lines are necessary in Un*x in. In Windows you can leave them in or you can take them out, but you need to rename the script to hw.pls. Leaving the lines in has the advantage that the script will also work in Un*x without any change.

For more information see section The script interpreter.

The Ciao initialization file (Un*x)

The Ciao toplevel can be made to execute upon startup a number of commands (such as, e.g., loading certain files or setting certain Prolog flags) contained in an initialization file. This file should be called .ciaorc and placed in your home directory (e.g., ~, the same in which the .emacs file is put). You may need to set the environment variable HOME to the path of this directory for the Ciao toplevel shell to be able to locate this file on startup.

Printing manuals (Un*x)

As mentioned before, the manual is available in several formats in the reference directory within the doc directory in the Ciao distribution, including postscript or pdf, which are specially useful for printing. These files are also available in the DOCROOT directory specified during installation. Printing can be done using an application such as ghostview (freely available from http://www.cs.wisc.edu/~ghost/index.html) or acrobat reader (http://www.adobe.com, only pdf).

An introduction to the Ciao emacs environment (Un*x)

While it is easy to use Ciao with any editor of your choice, using it within the emacs editor/program development system is highly recommended: Ciao includes an emacs mode which provides a very complete application development environment which greatly simplifies many program development tasks. See section Using Ciao inside GNU emacs for details on the capabilities of ciao/ emacs combination.

If the (freely available) emacs editor/environment is not installed in your system, we highly recommend that you also install it at this point (there are instructions for where to find emacs and how to install it in the Ciao installation instructions). After having done this you can try for example the following things:

We encourage you once more to read section Using Ciao inside GNU emacs to discover the many other functionalities of this environment.

Keeping up to date (Un*x)

You may want to read section Beyond installation for instructions on how to sign up on the Ciao user's mailing list, receive announcements regarding new versions, download new versions, report bugs, etc.

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