Re: Substituting Environment variables in Environment variables in QSH

Hmmm. As usual I get a bit confused in the i(ntegrated) world we live in on the System i. What threw me off, and lead me down the wrong path, is that the variables I set using WRKENVVAR are all available when I start Qshell, which led me to mistakenly believe that variable substitution would work in Qshell using those variables I set before I started Qshell. Well, since they ARE accessible to QShell it would be a nice enhancement if they functioned similarly to the way other Environment Variables do in Windows and Linux.

Here is the situation. I have an AIX based utility that works fine within Qshell. The problem is, and this is common to many open source projects, is that the projects continue to change versions frequently. So I may have a situation where version 1.1 of MyCoolProject is named MyCoolProject-1.1 and is extracted into folder /MyCoolProject-1.1 Well about a week later I see that MyCoolProject version 1.2RC1 is available. I download and extract it to folder /MyCoolProject-1.2RC1 Now I need to go into my Path and Classpath settings in a shell script and change those references OR change the ALL the environment variables that have the "old" folder reference in them OR rename folders completely so they have the same name (like /MyCoolProject ) renaming the original to something else and renaming the new folder to the "generic" name. That makes it tough to test differences in versions. In Windows (or Linux) I just change a single environment variable and all the other variables that reference that variable immediately pick up the change. "Switching" between versions is easy.

I could wrap the call the QSH and the launching of the utility in a CL command and handle the setting of the variable there, I guess. I was hoping for something simple and easy like setting one variable and running QSH.

Thanks, again, for setting me straight. I'll need to think on this a bit.

Pete


Scott Klement wrote:

Hi Pete,

Seeing your instructions below (thanks!) I realize that I should have clarified that I want to set the variables using the WRKENVVAR command.

WRKENVVAR?? That's a whole different subject altogether, Pete! Your last message stated that you were using QSH (in the subject line) and WRKENVVAR is not part of QSH, and that's what threw me off.

Anyway... the ability to use $VAR inside another variable is purely a Unix-shell thing. You can do it from within QShell, since QShell emulates a Unix-shell. But, WRKENVVAR is a CL command. (as are ADDENVVAR and CHGENVVAR which is more likely what you really mean) In CL, you can't insert an environment variable by preceding it with a dollar-sign... that's just not part of CL's syntax.

CL is not a good language for working with environment variables -- at present, it doesn't even have a means of retrieving the value of an environment variable without calling an API.

Here's an example of how you might do this in RPG, however:

H DFTACTGRP(*NO)

D getenv PR * extproc('getenv')
D varname * value options(*string)
D putenv PR 10i 0 extproc('putenv')
D varval * value options(*string)

D MY_HOME s 1024A varying
D CLASSPATH s 1024A varying
D val s *

/free

val = getenv('MY_HOME');
if (val = *NULL);
my_home = '';
else;
my_home = %str(val);
endif;

val = getenv('CLASSPATH');
if (val = *NULL);
classpath = '';
else;
classpath = %str(val);
endif;

classpath += ':' + my_home;
putenv('CLASSPATH=' + classpath);
return;

/end-free

As you can see... it's waaaay easier to do in QShell. (Though, the RPG code will certainly run faster!) Consider setting your variable in QShell if possible.