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From: leo@philmds.UUCP (Leo de Wit)
Newsgroups: comp.unix.questions,comp.unix.wizards
Subject: Re: Subshell Variable
Keywords: Subshell Variable
Message-ID: <963@philmds.UUCP>
Date: 26 Feb 89 13:25:47 GMT
References: <424@unicom.UUCP>
Reply-To: leo@philmds.UUCP (Leo de Wit)
Organization: Philips I&E DTS Eindhoven
Lines: 34

In article <424@unicom.UUCP> sayah_k@unicom.UUCP (KIANUSCH... Yes, Kianusch himself !!!) writes:
|Is there a way to exports system-variables from subshell, running in background
|to the main shell?
|
|I tried and tried and tried... but with no results... :-(
|

You haven't tried the following (assuming you don't need signal 5 in
the main shell). You can use it in all kinds of ways to communicate
between a parent and its child shell; I saw the idea first presented by
Maarten Litmaath to implement a 'cd with prompt-to-path conversion'
kind of cd alias for the Bourne shell.

Script started on Sun Feb 26 13:51:22 1989
philmds> trap ". .readvar" 5
philmds> trap
5: . .readvar
philmds> (echo "NEWVAR=newvalue export NEWVAR" >.readvar; kill -5 $$)&
19795
philmds> 
[1]    Done                 ( echo "NEWVAR=newvalue export NEWVAR"; kill -5 $$ )
philmds> echo $NEWVAR

philmds> echo $NEWVAR
newvalue
philmds> 

script done on Sun Feb 26 13:55:43 1989

Note the somewhat peculiar behaviour of the main shell: the trap seems to be
honoured only after execution of the next command. Maybe someone else has a
reasonable explanation of this?

    Leo.