Here's an example of data that would be stored in a plain text XML file. 
<Dataentry>
    <Data>aaaaaa</Data>
    <Data>aaaaaa</Data>
    <Data>aaaaaa</Data>
</Dataentry>
<Dataentry>
    <Data>aaaaaa</Data>
    <Data>aaaaaa</Data>
    <Data>aaaaaa</Data>
<Dataentry>
</Dataentry>
    <Data>aaaaaa</Data>
    <Data>bbbbbb</Data>
    <Data>aaaaaa</Data>
<Dataentry>
</Dataentry>
    <Data>aaaaaa</Data>
    <Data>aaaaaa</Data>
    <Data>aaaaaa</Data>
</DataEnd>

[download]
I'm going to read the file one line at a time and pull data between data tags /<Data>(.*)</Data>/
When the data in $1 matches bbbbbb I want it to pull the whole xml record. ie: 
<DataStart>
    <Data>aaaaaa</Data>
    <Data>bbbbbb</Data>
    <Data>aaaaaa</Data>
<DataEnd>

[download]
The problem is how do I read lines backwards to grab the preceding <Dataentry> tag and then everything from that start point to the next </Dataentry> tag? There could be any number of lines between tags so its not a fixed point to read backwards to. The name of the tag entry does not change though, nor will what I am searching for with the initial match.

I can whip up the rest of the code without issue, so please don't dwell on the obvious lack of code provided, the part I am unclear on is explained above.
Thanks in advance if you can explain to me to how this is done or even provide an example.

In reply to Match on line, read backwards to opening xml tag then forward to closing tag by shadowfox

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