Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.questions
Subject: Re: unix shell programming question
Summary: Use eval
Message-ID: <1990Feb26.145323.22611@virtech.uucp>
Date: 26 Feb 90 14:53:23 GMT
References: <504@lkbpyr.UUCP>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Organization: Virtual Technologies Inc., Sterling VA
Lines: 34

In article <504@lkbpyr.UUCP> jonas@lkbpyr.UUCP (Jonas Heyman) writes:
>echo $str1        #This is OK   "string 1"
>echo $str2 	  #This is OK   "string 2"
>
>for loop in 1 2
>do
>	aa=$str$loop     #Here I want "string 1" and "string 2"
	^^^^^^^^^^^

>	echo $aa
>
>	echo $str$loop   #Here I want "string 1" and "string 2"
        ^^^^^^^^^^^^^^
>done

Replace the indicated lines with:

	eval aa=\$str$loop     #Here I want "string 1" and "string 2"

and

	eval echo \$str$loop   #Here I want "string 1" and "string 2"

respectively, and you will get the output you desire.  Eval just tells
the shell to read the arguments as input and execute them.  this
causes the rest of the line to be scanned twice.  On the first scan, the
\$str is converted to $str and the $loop is converted to 1 or 2. The
second scan interprets the $str1 or $str2

-- 
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| Conor P. Cahill     uunet!virtech!cpcahil      	703-430-9247	!
| Virtual Technologies Inc.,    P. O. Box 876,   Sterling, VA 22170     |
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