All ARexx programs are started by the resident process. The resident process creates a new process, loads the ARexx program into the new process, and invokes the ARexx interpreter. Besides keeping track of all currently-executing programs, the resident process also manages ARexx resources, including the Clip List and the Library List, both described in a later section. Note that the resident process is also an ARexx host application, a program that can send and receive ARexx messages. Finding the Resident Process On the typical Amiga system the ARexx resident process is always active, launched from within the system startup file using the rexxmast command.
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William Hawes is no longer involved in development of Amiga programs and no other Amiga-related firm is financing new versions of ARexx. Notwithstanding this fact, the existing version of ARexx continues to be used, although it is not distributed with MorphOS.
From the ARexx manual: ARexx was developed on an Amiga computer with k bytes of memory and two floppy disk drives. The language prototype was developed in C using Lattice C , and the production version was written in assembly-language using the Metacomco assembler. Using ARexx, for example, one could request data from a database application and send it to a spreadsheet application. To support this facility, an application must be "ARexx compatible" by being able to receive commands from ARexx and execute them.
A database program might have commands to search for, retrieve, and save data — the MicroFiche Filer database has an extensive ARexx command set. A text editor might have ARexx commands corresponding to its editing command set — the Textra editor supplied with JForth can be used to provide an integrated programming environment.
The AmigaVision multimedia presentation program also has ARexx port built in and can control other programs using ARexx. ARexx can increase the power of a computer by combining the capabilities of various programs.
Other programming languages made distinctions between integers, floating point numbers, strings, characters, vectors, etc. In contrast, REXX systems treat all data as strings of characters, making it simpler to write expressions and algorithms.
As is often the case in dynamically scoped languages, variables are not declared before using them, they come into being on their first use. ARexx scripts benefit from an error handling system which monitors execution and responds accordingly. The programmer can choose to suspend and resume the execution of the program as needed. The ARexx command set is simple, but in addition to the commands there are the functions of its Amiga reference library rexxsyslib.
It is also easy to add other libraries or individual functions. ARexx scripts can also be invoked as functions from other ARexx scripts.
Examples of ARexx solutions to common problems[ edit ] Implementing new features and capabilities via scripts[ edit ] If end user is using a program which builds animations by joining various bitmap image files but which lacks image processing capabilities, he could write an ARexx script which performs these actions: ARexx locates the image files in their directories ARexx loads first image The image is loaded into paint program which performs modifications to file The modified image is stored into another directory ARexx repeats procedure on any image in the directory The paint program is closed and the animation program is loaded The animation is built The animation is saved in its directory The animation program is closed Avoiding repetitive procedures[ edit ] EqFiles.
This script uses the ALeXcompare program  to compare files, and then finds all duplicates in a set of files and returns output by highlighting any results in a different color. For example, a simple ARexx program could be written to print a warning message on the screen of the monitor, or play an audio alert signal if a certain Amiga program stops, faults or has finished its scheduled job. The following script is a minimal ARexx script that displays warnings depending on events that take place.
AmigaOS Manual: ARexx
All rights reserved. It is especially useful as a scripting language which allows you to control and modify applications and to direct how they interact with each other. This manual introduces you to ARexx, tells you how to create ARexx programs and provides a reference section of ARexx commands. Chapter 1. Introducing ARexx This chapter gives an overview of ARexx, how it works on the Amiga, and the basic features of the programming language. Chapter 2. Getting Started This chapter tells you where to store your ARexx programs, how to execute an ARexx program, and provides several programming examples.
William Hawes is no longer involved in development of Amiga programs and no other Amiga-related firm is financing new versions of ARexx. Notwithstanding this fact, the existing version of ARexx continues to be used, although it is not distributed with MorphOS. From the ARexx manual: ARexx was developed on an Amiga computer with k bytes of memory and two floppy disk drives. The language prototype was developed in C using Lattice C , and the production version was written in assembly-language using the Metacomco assembler.