grep – Extract an attribute value from XML

grepxml

Using Bash,

File:

<?xml version="1.0" encoding="UTF-8"?>
<blah>
    <blah1 path="er" name="andy" remote="origin" branch="master" tag="true" />
    <blah1 path="er/er1" name="Roger" remote="origin" branch="childbranch" tag="true" />
    <blah1 path="er/er2" name="Steven" remote="origin" branch="master" tag="true" />

</blah>

I have tried the following:

grep -i 'name="andy" remote="origin" branch=".*\"' <filename>

But it returns the whole line:

<blah1 path="er" name="andy" remote="origin" branch="master" tag="true" />

I would like to match the line based on the following:

name="andy"

I just want it to return:

master

Best Answer

Use an XML parser for parsing XML data. With xmlstarlet it just becomes an XPath exercise:

$ branch=$(xmlstarlet sel -t -v '//blah1[@name="andy"]/@branch' file.xml)
$ echo $branch
master

Related Solutions

Retrieve attribute value from xml with namespaces using xmllint

Yes, don't use sed on XML. It's bad news.

I think your problem is actually a simple matter of quoting - you quote your xpath in single quotes, and Elem is also in single quotes.

I don't have a copy of xmllint handy, but this works:

#!/usr/env/perl

use strict;
use warnings;

use XML::LibXML;

my $xml = XML::LibXML -> load_xml ( IO => \*DATA ); 
print $xml -> findnodes('//XML/*[local-name()="Elem"]');

__DATA__
<?xml version="1.0" encoding="UTF-8"?>
<XML>
    <hhi:Elem xmlns:hhi="http://www.w3.org/TR/html4/" version="1.0" sn="101"> 
    </hhi:Elem>
</XML>

That prints:

sn="101"

You don't need the XML either, because // denotes "anywhere in tree". So you could use:

//*[local-name()="Elem"]/@sn
/XML/*[local-name()="Elem"]/@sn

For the sake of completeness, with registering the namespace you could do it like this:

#!/usr/env/perl

use strict;
use warnings;

use XML::LibXML;

my $xml = XML::LibXML -> load_xml ( IO => \*DATA ); 
my $xpc = XML::LibXML::XPathContext -> new;
$xpc -> registerNs('x', 'http://www.w3.org/TR/html4/');
print $xpc -> findnodes('/XML/x:Elem/@sn', $xml);

__DATA__
<?xml version="1.0" encoding="UTF-8"?>
<XML>
    <hhi:Elem xmlns:hhi="http://www.w3.org/TR/html4/" version="1.0" sn="101"> 
    </hhi:Elem>
</XML>

Now, I know this doesn't directly help with xmllint, aside from allowing testing of the xpath you're using. But I think it likely that it's quotes tripping you up, not the xpath.

Can I suggest you need:

xmllint --xpath '//*[local-name()="Elem"]/@sn' FILE_1.xml

Best Answer

Related Solutions

Retrieve attribute value from xml with namespaces using xmllint

Related Question