Rexx Anywhere!

This web page attempts to fill a void for people wanting to create Rexx execs that will execute on any platform or Rexx implementation. It is geared toward the intermediate-advanced Rexx programmer and assumes some knowledge of the language.

As you are probably aware, you can write general purpose Rexx execs which will execute anywhere with little or no changes. Problem in Paradise: If that Rexx exec does file I/O, it will not execute everywhere. Unfortunately, file I/O was not implemented consistently in the different versions of Rexx (even in the ones developed by IBM).

For this reason, you will want to trap the environment that the Rexx exec is executing in and perform different processing. Here are the main points covered by the Rexx Anywhere! web page:

A collection of environment testing results
Sample code that takes the different environments into account and returns consistent results
Some Portability issues
CMS/TSO Pipelines
A Call for contributions!!!
Other References

The goal is to be able to write Rexx execs that will execute on any platform and take the steps needed to perform functions differently on that platform when needed. With little effort, you can have portable versions of your general purpose Rexx execs. Otherwise you will have a Rexx exec that

WRECKS Somewhere!.
But keep in mind that not all Rexx execs need this capability, only general purpose ones that don't invoke operating system features. Read on if you have Rexx execs that you want to be portable.

Collection of environment results

I've written a small Rexx exec called rexxver that shows the results from the ADDRESS(), PARSE SOURCE ... and PARSE VERSION ... statements. These environment results will give us the information needed to write code that is portable and reacts (when needed) to process differently on a given platform or implementation.

Here are the results of my testing and contributions sent to me:

Platform	ADDRESS()	Env "PARSE SOURCE Env"	REXXVER Output
z/OS :: TSO	TSO	TSO	+
z/OS :: PGM=IRXJCL	MVS	TSO	+
z/OS :: System Rexx (AXR) [2007-02-16]	TSO	TSO	+
z/OS :: OMVS Shell	SH	TSO (Don't use this field, use this)	+
z/OS :: Rexx Compiler 3.0	MVS	TSO	+
z/OS :: CICS	REXXCICS	CICS	+
z/OS :: CA GSS IMOD [2013-04-25]	ISERVE	GSS	+
VM/ESA	CMS	CMS	+
VSE/ESA	VSE	VSE	+
AIX/6000	ksh	AIX/6000	+
Object Rexx :: Windows 95	CMD	Windows95	+
Object Rexx :: Linux	bash	LINUX	+
Object Rexx :: OS/2	CMD	OS/2	+
OS/2	CMD	OS/2	+ +
PC/DOS 7.0	COMMAND	DOS	+
AS/400 V4R1	COMMAND (the CL environment) EDIT (Possible editor) LIBL/ABC (your ABC program)*	OS/400	+
NetRexx	n/a	JAVA	+
Regina Rexx :: Windows 95 and NT	SYSTEM	WIN32	+
Regina Rexx :: All UNIX versions	SYSTEM	UNIX	+
Regina Rexx :: Open-VMS	SYSTEM	VMS	+
Regina Rexx :: EPOC32 (Psion 5/5mx/Revo etc) [2001-09-09]	SYSTEM	EPOC32-MARM	+
Regina Rexx :: QNX 4.2.5 [2001-09-09]	SYSTEM	QNX	+
BREXX :: Windows 95 (MS/DOS prompt)	SYSTEM	MSDOS	+
uniREXX :: Solaris 2.6	UNIX	UNIX	+
REXX-imc :: FreeBSD 2.2.6	UNIX	UNIX	+
Quercus Personal Rexx for DOS	DOS	PCDOS	+
Quercus Personal Rexx for Windows	COMMAND	WIN	+ +
Enterprise Rexx	COMMAND	WIN	+
Amiga Regina Rexx	SYSTEM	AMIGA	+
Amiga ARexx	REXX	COMMAND	+
Editor section
VM/ESA 1.2.2 XEDIT	XEDIT	CMS	+
SPF/PC Rexx exec edit macro	ISREDIT	WINDOWS	+
Tritus/SPF edit macro (DOS)	ISREDIT	Garbage, see full output	+
Tritus/SPF edit macro (OS/2)	ISREDIT	OS/2	+
Mark Hessling's THE editor	THE	Based on the OS: WIN32, OS/2, UNIX or DOS.	+

View the full output from the REXXVER Rexx exec on each platform. This list above isn't intended to be a list of every Rexx implementation. It is a list of the Environment results that I've tested or people have sent me. If your favorite Rexx isn't in the list, then it should be...

For more information on invoking Rexxver as a Java application and applet, go to my Rexx Anywhere! - NetRexx page.

Sample code

I've provided these Rexx execs that demonstrate detecting the Rexx environment and processing differently:

Perform file input in byte-oriented mode using the INPUTB Rexx exec.
An example of a real world Rexx exec that uses this technique is my IMGINFO exec.
Perform file input in record-oriented mode in exec INPUTR Rexx exec.
An example of a real world Rexx exec that uses this technique is my LTEXHIST exec.

Portability issues

If a Rexx implementation provides file I/O, it probably implements the LINES(), CHARIN() and CHARS() functions except for OS/390 (MVS) and VM.

The linein/lineout/chars/charin/charout functions were added to VM with CMS level 10 (need to double check) and should be available when the Rexx version is "4.00" or higher. Thanks to Carl Forde for pointing this out.

On my VM/ESA 1.1 system, I found that the stem variable must be typed in uppercase on the EXECIO statement. This isn't an error on TSO. For example:

Good: "EXECIO * DISKR "fn ft fm" (STEM FILEIN. FINIS"
Bad: "EXECIO * DISKR "fn ft fm" (STEM filein. FINIS"

I'm not a VMer and haven't dug into this very far.

For you IBM mainframe Rexx programmers: Don't use the 'notsign equal' expression as in "¬=". The notsign character is defined in the EBCDIC character set but not in the standard ASCII character set. When you transfer files from your mainframe to a non-EBCDIC platform, the ¬ sign (hex 5F) gets translated to something undesirable like hex AC. Suggestion:

Use "<>" or "\=" to specify not equal For example:

Good: IF this <> that THEN ...

Good: IF this \= that THEN ...

Bad: IF this ¬= that THEN ...

Now you may be thinking: I'm on Windows 95 or some other ASCII platform and I see the notsign: (¬) on this page. -- I had to use a special HTML code to specify the notsign, view the source of this page to see it. In fact, many people have web browsers that won't display the ¬ notsign. If you want to know more, see A tutorial on character code issues

There isn't a good source for determining which Rexx functions and features are available for a given system and release. Here is a short (and incomplete attempt):

TSO/E Rexx V2.1 through V2.4 (from IBMLINK)
TSO/E 2.5: MVSVAR() function, SYSCPUS() function, SMSINFO parameter was added to the LISTDSI statement, and some misc CLIST control variables.
Our VM/ESA 1.1 system doesn't have the B2X() and X2B() functions.

Requirements on what is needed on the first line of a Rexx exec:
- Under IBM's AIX/6000 Rexx implementation, you need "#!/bin/rexx" on the first line of a Rexx exec.
- Under S/REXX, you need "#! /home/xed/srexx" on the first line of a Rexx exec.

CMS/TSO Pipelines

Distinguishing Levels of CMS/TSO Pipelines

A Call for contributions

I don't have access to every Rexx implementation. Please send me examples of executing REXXVER on your system. If you see any bugs with my sample code, please email me. My email address is on my contact page. Or send me email about what you think of this page. Do you have any sample code that you've written that you would like to make available?

Hint: On many operating systems like MS/DOS, PC DOS, OS/2, Windows 95/NT DOS prompt and UNIX, you can pipe the output of the Rexxver Rexx exec to a file. Here is an example of putting the output to a file for easy emailing:

T H A N K S

I'd like to thank the following people who have contributed information and testing results:

Jim Alves, Eric Bitterman, John A Cifonelli, John C. Ford, Carl Forde,
Stephen Ferg, Mark Hessling, Rudy Kohut, Marc Irvin, Tim Launchbury,
David McRitchie, Gilbert Saint-flour, John Saxton, Ian Smith, Leif Trdger and R.F. van der Woude

Other References

Book The Rexx Handbook (ISBN 0-07-023682-8, 1992) edited by Gabriel Goldberg and Philip Smith III has a chapter called SAA Portability (written by Stephen G. Price). This chapter has an extensive list of incompatibilities among the IBM Rexx implementations and a nice set of rules for safe Rexx.

Right after I created this page, I stumbled across my copy of this book and wouldn't you know someone already did a more extensive portability guide!
The Rexx Handbook is currently out of print but if you email Gabriel Goldberg, he'd be more than happy to sell you a copy of the book. You can also visit Gabe Goldberg's Home Page.

Read a book review of The REXX Handbook courtesy of Xephon.
Vendor The Workstation Group Ltd.'s uni-REXX FAQ has good suggestions for writing portable code.

I like their suggestion on how to list files on different operating systems by detecting the environment and issuing the right command for that system.
Vendor Quercus Systems's site has a wealth of Rexx information including a page on Rexx Pitfalls
Neil Hancock's TSO-REXX Frequently Asked Questions hosted on Rodney D. Hinds' MVS REXX page has some portability tips.
Steve Ferg's take on Rexx portability
John C. Ford's explanation of REXX VSE return codes
The Enterprise Systems Journal has a few articles on Rexx which are easily found on their search page.
The Rexx Language Association has a newsletter and other Rexx Goodies. Some portability links there:
- BREXX - Getting Better by Leaps and Bounds (see the I/O stuff)
- Safe REXX on the Desktop (part 2)
The Rexx Language - IBM's Rexx page has pointers to just about everything Rexx.

Why "Rexx Anywhere!"? Because "Rexx Ubiquitous!" just doesn't have the right ring...

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