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From: rbr@bonnie.ATT.COM (228-4197,ATTT)
Newsgroups: comp.unix.shell
Subject: Re: Passing a var thru a file
Message-ID: <1991Jun18.173451.20361@cbnewsl.att.com>
Date: 18 Jun 91 17:34:51 GMT
References: <1991Jun18.153222.20836@cid.aes.doe.CA>
Sender: news@cbnewsl.att.com (NetNews Administrator)
Reply-To: rbr@bonnie.ATT.COM (Bob Rager)
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Organization: AT&T Bell Laboratories
Lines: 28

In article <1991Jun18.153222.20836@cid.aes.doe.CA> afsipmh@cidsv01.cid.aes.doe.CA () writes:
>Say i have a file that (just for the sake of this question) contains
>just one word:
>$ENVAR
>
>Say $ENVAR is an environmental variable
>
>What is it about the shell that prevents interpretation:
>
>#!/bin/sh
>var=`cat file`
>echo $var     #gives (literally) $ENVAR
>echo `echo $var`  #also gives (literally) $ENVAR
>-- 
>Pat Hertel                 Canadian Meteorological Centre
>Analyst/Programmer         2121 N. Service Rd.        
>phertel@cmc.aes.doe.ca     Dorval,Quebec             
>Environment Canada         CANADA           H9P1J3

The shell never sees $ENVAR as a variable, only a string of arbitrary
characters.

Try:

var=`cat file`
echo `eval $var`

Bob Rager