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Rexx (''REstructured eXtended eXecutor'') is an interpreted programming language developed at IBM by Mike Cowlishaw. It is a structured, high-level programming language designed for ease of learning and reading. Proprietary and open source REXX interpreters exist for a wide range of computing platforms; compilers exist for IBM mainframe computers. Rexx is widely used as a scripting and macro language, and is often used for processing data and text and generating reports; these similarities with Perl mean that Rexx works well in Common Gateway Interface (CGI) programming and it is indeed used for this purpose. Rexx is the primary scripting language in some operating systems, e.g. OS/2, MVS, VM, AmigaOS, and is also used as an internal macro language in some other software, such as KEDIT, THE and the ZOC terminal emulator. Additionally, the Rexx language can be used for scripting and macros in any program that uses Windows Scripting Host ActiveX scripting engines languages (e.g. VBScript and JScript) if one of the Rexx engines is installed. Rexx is supplied with VM/SP on up, TSO/E Version 2 on up, OS/2 (1.3 and later, where it is officially named ''Procedures Language/2''), AmigaOS Version 2 on up, PC DOS (7.0 or 2000), and Windows NT 4.0 (Resource Kit: Regina). REXX scripts for OS/2 share the filename extension .cmd with other scripting languages, and the first line of the script specifies the interpreter to be used. REXX macros for REXX-aware applications use extensions determined by the application. A Rexx script or command is sometimes referred to as an ''EXEC'' in a nod to Rexx's role as a replacement for the older EXEC command language on CP/CMS and VM/370 and EXEC 2 command language on VM/SP. == Features == Rexx has the following characteristics and features: * Simple syntax * The ability to route commands to multiple environments * The ability to support functions, procedures and commands associated with a specific invoking environment. * A built-in stack, with the ability to interoperate with the host stack if there is one. * Small instruction set containing just two dozen instructions * Freeform syntax * Case-insensitive tokens, including variable names * Character string basis * Dynamic data typing, no declarations * No reserved keywords, except in local context * No include file facilities * Arbitrary numerical precision * Decimal arithmetic, floating-point * A rich selection of built-in functions, especially string and word processing * Automatic storage management * Crash protection * Content addressable data structures * Associative arrays * Straightforward access to system commands and facilities * Simple error-handling, and built-in tracing and debugger * Few artificial limitations * Simplified I/O facilities * Unconventional operators * Only partly supports Unix style command line parameters, except specific implementations * Provides no basic terminal control as part of the language, except specific implementations * Provides no generic way to include functions and subroutines from external libraries, except specific implementations Rexx has just twenty-three, largely self-evident, instructions (such as call, parse, and select) with minimal punctuation and formatting requirements. It is essentially an almost free-form language with only one data-type, the character string; this philosophy means that all data are visible (symbolic) and debugging and tracing are simplified.Rexx's syntax looks similar to PL/I, but has fewer notations; this makes it harder to parse (by program) but easier to use, except for cases where PL/I habits may lead to surprises. One of the REXX design goals was the principle of least astonishment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Rexx」の詳細全文を読む スポンサード リンク
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