Shell Script - Update Fields in plist/xml (data serialization) file - after specific field match - using awk

We face the need to update the XML, where tag value or key-value pairs needs to be modified, using shell script. Tried the below way:

Say XML file appears like:


<?xml version="1.0" encoding="UTF-8"?>
<key>Server</key>
<lex>
<key>Location</key>
<string>Homestead</string>
<key>days</key>
<integer>60</integer>
</lex>

<key>server</key>
<lex>
<key>host</key>
<string>ab.host.com</string>
<key>days</key>
<integer>30</integer>
</lex>

Now we want to update the field host value. The below script call can do it:

./updatexml.sh bcd.host.com

where updatexml.sh looks like:

#! /bin/bash

var=$1

awk -F'[<>]' '

        /<key>Client<\/key>/ {

                f = 1

        }

        /<key>host<\/key>/ {

                s = 1

        }

        {

if (f && s && /<value>/) {

sub($3,"'$var'",$0); 

f = 0

s = 0

        }

print 

}

' 1.xml > temp.xml

mv temp.xml 1.xml 

Explanation:

set a flag 'f', after the occurrence of the tag "<key>Client</key>" and on finding occurrence of "<key>host</key>" set another flag. Then it is self explicable, on match of both flags true and tag <value> we replace the third column of line with variable.