CODEWITHSUNDEEP
xmlbashxml-parsingxmlstarlet
Igor Elizarov
Igor Elizarov

Reputation: 11

xmlstarlet: Invalid expression: [xpath] compilation error: element for-each*

There is my XML:

<?xml version="1.0" encoding="UTF-8"?>
<CurrentUsage xmlns="http://www.vmware.com/vcloud/v1.5" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.vmware.com/vcloud/v1.5 http://cloud.com/api/v1.5/schema/master.xsd">
    <Link rel="up" href="cloudurl" type="application/vnd.vmware.vcloud.vm+xml"/>
    <Metric name="cpu.usage.average" unit="PERCENT" value="3.4"/>
    <Metric name="cpu.usage.maximum" unit="PERCENT" value="3.4"/>
    <Metric name="cpu.usagemhz.average" unit="MEGAHERTZ" value="81.0"/>
    <Metric name="mem.usage.average" unit="PERCENT" value="15.99"/>
    <Metric name="disk.provisioned.latest" unit="KILOBYTE" value="503337805"/>
    <Metric name="disk.used.latest" unit="KILOBYTE" value="290391113"/>
</CurrentUsage>

I'm using xmlstarlet tool, and able to get list of values with:

xmlstarlet sel  -t -v //@value  test.xml

But I really stuck with getting particular value by name of metric (as an example for "cpu.usage.average"). I've read tons of examples, tried to use expressions like:

xmlstarlet sel  -t -m "//[@name='cpu.usage.average']" -v //@value test.xml

But this drops me into:

Invalid expression: //[@name='cpu.usage.average'] 
compilation error: element for-each*

How do I get particular value in such simple case?

Upvotes: 1

Views: 1171

Answers (1)

kjhughes
kjhughes

Reputation: 111686

Your XPath is malformed. Use //*[@name='cpu.usage.average'] for -m as a fix (and also to bypass namespaces -- otherwise you'll have to declare a namespace prefix) and @value for -v.

Altogether, this xmlstarlet command

xmlstarlet sel  -t -m "//*[@name='cpu.usage.average']" -v @value test.xml

will return

3.4

for your XML, as requested.

Upvotes: 1

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