$ cat /tmp/in
host=www.test.com
port=8080
binding="dynamic" or "other" or "something else"
key1=value1
key2=value2
key3=value4
policy="<wsp policyFile='mypolicy.policy' >
$ cat /tmp/in2
<file port="7001" binding="static" />
<details host="http//test.com" />
<policy node> insert value of policy here only if binding=dynamic otherwise leave it
</policy node>

</file>
$ cat test.pl
#!/usr/local/bin/perl -w

open CONFIG, '<', '/tmp/in';
open F, '<', '/tmp/in2';

while (<CONFIG>) {
        ($key, $value) = split /=/,$_,2;
        chomp($config{$key} = $value);
}

while ($line = <F>)  {
        foreach (keys %config) {
                $line =~ s/($_=)[^ ]*/$1"$config{$_}"/;
        }
        print $line;
}
close F;
close CONFIG;
$ perl test.pl
<file port="8080" binding=""dynamic" or "other" or "something else"" />
<details host="www.test.com" />
<policy node> insert value of policy here only if binding=""dynamic" or "other" or "something else"" otherwise leave it
</policy node>

</file>

$ cat /tmp/in
host=www.test.com
port=8080
binding="dynamic" or "other" or "something else"
key1=value1
key2=value2
key3=value4
policy="<wsp policyFile='mypolicy.policy' >
$ cat /tmp/in2
<file port="7001" binding="static" />
<details host="http//test.com" />
<policy node> insert value of policy here only if binding=dynamic otherwise leave it
</policy node>

</file>
$ cat test.pl
#!/usr/local/bin/perl -w

open CONFIG, '<', '/tmp/in';
open F, '<', '/tmp/in2';

while (<CONFIG>) {
        ($key, $value) = split /=/,$_,2;
        chomp($config{$key} = $value);
}

while ($line = <F>)  {
        foreach (keys %config) {
                $line =~ s/($_=)[^ ]*/$1"$config{$_}"/;
        }
        print $line;
}
close F;
close CONFIG;
$ perl test.pl
<file port="8080" binding=""dynamic" or "other" or "something else"" />
<details host="www.test.com" />
<policy node> insert value of policy here only if binding=""dynamic" or "other" or "something else"" otherwise leave it
</policy node>

</file>