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How can I get the value from an attribute using xmllint and XPath?
Asked Answered
xmlshellxpath
G

6

50

I want to get the value of name and put it in a variable using XMLLint

<body>
<value name="abc"></value>
</body>

echo 'cat //body/value/@name' | xmllint --shell "test.xml"

/ >  -------
 name="abc"
/ >

So I want to assign the value "abc" to variable $test

Grafton answered 23/7, 2012 at 11:12 Comment(0)
C
55

You need to use fn:string(), which will return the value of its argument as xs:string. In case its argument is an attribute, it will therefore return the attribute's value as xs:string.

test=$(xmllint --xpath "string(//body/value/@name)" test.xml)
Cymatium answered 10/8, 2012 at 16:49 Comment(3)
unfortunately --xpath is unsupported on a lot of installations – Goon
This only shows the value for a single element, is it possible to get multiple matches? – Holtz
@CiroSantilli郝海东冠状病六四事件法轮功 You can get multiple matches with xmllint --xpath "//body/value/@name", but they will be all on the same line, unless you have version 2.9.9 or newer of the package libmxl2-utils. – Fitch
D
8

Try this, it's not beautiful but it works :)

I just erase lines containing > from stdout , cut the string to get the second part after the = , and delete "

test=$(echo 'cat //body/value/@name' | xmllint --shell "test.xml" | grep -v ">" | cut -f 2 -d "=" | tr -d \"); 
echo $test
Discus answered 27/7, 2012 at 8:28 Comment(2)
Use xmllint so you don't have to use REs to parse XML. Realize you have to use REs to parse the output of xmllint. – Epicenter
why does it print ------- before the name attribute value? how to remove it? – Cervicitis
L
6

An approach with a helper awk command that supports multiple attributes (a streamlined version of ego's approach):

echo 'cat //*/@name' | xmllint --shell file | awk -F\" 'NR % 2 == 0 { print $2 }'

The awk command:

  • splits xmllint's output lines into fields by " chars. (-F\")

    • Note that xmllint normalizes quoting around attribute values to "..." on output, even if the input had '...', so it's sufficient to split by ".

  • only processes even-numbered lines (NR %2 == 0), thereby filtering out the separator lines that cat invariably prints.

  • print $2 then prints only the 2nd field, which is the value of each attribute without the enclosing "...".

Assuming the following sample XML in file:

<body>
  <value name="abc"></value>
  <value name="def"></value>
</body>

the above yields:

abc
def
Lancelle answered 27/5, 2017 at 18:0 Comment(2)
this works perfectly for me, thanks. Do you also have a nice way of assigning the values to different variables. Like VAR_1=$(echo 'cat //*/@name' | xmllint --shell file | awk -F\" 'NR % 2 == 0 { print $2 }') ? – Illfounded
@dieHellste: You can read the output lines into variables (either in a while loop or, in Bash, into an array with read -a); if you need further guidance, please ask a new question. – Lancelle
A
3

I recently had to port my original simpler solution using --xpath to a platform lacking this feature, so had to adopt the "cat" solution too. This will handle multiple matches, tested on Ubuntu 12.04 and Solaris 11:

getxml() { # $1 = xml file, $2 = xpath expression
    echo "cat $2" | xmllint --shell $1 |\
    sed -n 's/[^\"]*\"\([^\"]*\)\"[^\"]*/\1/gp'
}

e.g. extracting instance names from a glassfish domain config:

$ getxml /tmp/test.xml "//server[@node-ref]/@name"
inst1
inst2

The sed post-processing just grabs all quoted values which was adequate for my needs (getting bits of glassfish config).

Antoinetteanton answered 5/6, 2014 at 3:23 Comment(0)
I
2

With the goal of matching multiple lines and extract the value of their homonymous attribute and building on previous answers this worked for me and it's shorter hehe

xmllint --xpath "//*/@value" file.xml | awk -F\" '{ print $2 }'
Ichthyosis answered 5/11, 2021 at 1:27 Comment(1)
even shorter :) xmllint --xpath "//*/@value" file.xml | cut -f2 -d\" – Cornu
P
-1

The next works for me:

xmllint --xpath '//o/@loc' file.xml | sed -n 's/[^\"]*\"\([^\"]*\)\"[^\"]*/\1\n/gp'
Prickly answered 30/1, 2023 at 9:44 Comment(1)
//o/@loc??? And why would one need this awful sed-command? – Ishmael

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