Tying multiple environment variables together

Tying multiple environment variables together

[Steve Talley]

Hi,

There are three environment variables that are used by various
programs, that all need to be the same value.  From .zshenv:

export JAVA_HOME=/usr/java
export JDKHOME=$JAVA_HOME
export JDK_HOME=$JAVA_HOME

Unfortunately when I change the value of one I have to change all
three.  Is it possible to tie the values together, so that after
changing one they all get changed?  Something along the lines of
typeset -T, but for environment variables?

Thanks,

Steve

Re: Tying multiple environment variables together

[Bart Schaefer]

On Apr 11, 10:18am, Steve Talley wrote:
}
} Unfortunately when I change the value of one I have to change all
} three.  Is it possible to tie the values together, so that after
} changing one they all get changed?

Not directly (though this sounds like a good basis for a zmodload
module of some kind).  The easiest thing is to use precmd() to force
two of them to always match the third, e.g.

	precmd() {
	    export JDKHOME=$JAVA_HOME
	    export JDK_HOME=$JAVA_HOME
	}

Then always change JAVA_HOME when you want to change all of them.

I believe recent versions of ksh have a syntax for specifying set/unset
callbacks on parameters, so zsh will probably pick up that feature before
long.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com

Zsh: http://www.zsh.org | PHPerl Project: http://phperl.sourceforge.net