Expansion of variables in sh scripts

[Chris Torek]

In article <1159 at valhalla.ee.rochester.edu> badri at valhalla.ee.rochester.edu
(Badri Lokanathan) writes:
>#!/bin/sh
>word=$1
>result=`awk "/^${word}/{print \$2}" datafile`
>echo $result
># This outputs the entire line, rather than the entry in the II column.

Yes.  Shell (sh, not csh) quoting is very easy to explain.  ""
quotes against file expansion; '' quotes against all expansion.
Any time a line is evaluated, one level of quoting is removed.
Backquotes evaluate the text inside the backquotes once.  Hence
"\$2" becomes $2 becomes nothing, and awk prints the whole line.

Note that this means you can use backquotes inside backquotes:

	foo=`eval echo \`basename ...\``

This is not directly possible in csh.
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In-Real-Life: Chris Torek, Univ of MD Computer Science, +1 301 454 7163
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