Here's how I would do it with XML::LibXML. The query searches for the TestElement with "Hello" and changes it to "Bye". 
use strict;
use warnings;
use XML::LibXML;

my $parser = XML::LibXML->new({"encoding" => "utf-8"});
my $doc = $parser->load_xml(string => "<XML> <TestElement>Hello</TestE
+lement><TestElement>Some Other Element</TestElement></XML>");

my $qry = "/XML[TestElement='Hello']/TestElement/text()";
my ($node) = $doc->findnodes($qry);
if (defined $node) {
    $node->setData("Bye");
}
else {
    die "no match for $qry";
}

print $doc->toString(), "\n";

[download]
Output: 
<?xml version="1.0"?>
<XML> <TestElement>Bye</TestElement><TestElement>Some Other Element</T
+estElement></XML>

[download]
Note that "Some Other Element" remains unchanged.

In reply to Re: Modify XML by richb
in thread Modify XML by perl@1983

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