Access attributes from XML in shell

Question

I'm trying to parse out values from a Widget config.xml using shell. I do want to use sed for this task. If there is something that sucks less than xsltproc, I'd love to know.

In this example I am after the id attribute value from the config.xml below:

<?xml version="1.0" encoding="UTF-8"?>
<widget xmlns="http://www.w3.org/ns/widgets" id="http://example.org/exampleWidget" version="2.0 Beta" height="200" width="200">
<name short="123">Foo Widget</name>
</widget>

I wish it was as simple as Jquery's attr: var id = $("widget").attr("id");

Currently this shell code utilising xsltproc fails:

snag () {
TMP=$(tempfile)
cat << EOF > $TMP
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="text" encoding="utf-8" indent="no"/>
<xsl:template>
<xsl:value-of select="$1"/>
</xsl:template>
</xsl:stylesheet>
EOF

echo $(xsltproc $TMP config.xml)
rm -f $TMP
}

ID=$(snag "widget/@id")

if test "$ID" = "http://example.org/exampleWidget"
then
 echo Mission accomplished.
else
 echo "<$ID> is wrong."
fi

Answer 1

template match="widget"

select value-of="@id"

Answer 2

<xsl:template xmlns:wgt="http://www.w3.org/ns/widgets" match="/wgt:widget"> <xsl:select value-of="@id" /> </xsl:template>

Answer 3

XMLStarlet (http://xmlstar.sourceforge.net/) is a nice command line tools that supports such queries:

xmlstarlet sel -N w=namespace -T -t -m "/w:widget/@id" -v . -n config.xml

Answer 4

You don't need XSLT if you're not doing a transform. If you only need to grab a value use XPath.

There's an xpath program that comes with Perl's XML::XPath module.

From the shell: ID=$(xpath config.xml 'string(/widget/@id)' )

( The string() function is to get only the value of the id.

/widget/@id by itself returns "id=value" )

If you only need to produce some other output depending on the value, you could do it all in xslt. There are also other XPath implementations available from other scripting languages: I've used Java's XPath from both rhino and Jython. There's also XQuery from the command line with Saxon.