Get xmllint to output xpath results \n-separated, for attribute selector

Question

How can I get xmllint to output multiple results of xpath selector for attributes \"per line\"?

Take this example:

Answer 1

I found that Ubuntu v.14 and v.18 use too old libxml2 versions. So i solved the issue mentioned in the topic by the recompiling of libxml2 v2.9.10.

1) Download the sources of libxml2 from http://linuxfromscratch.org/blfs/view/cvs/general/libxml2.html

2) Download the test suite:

$ wget http://www.w3.org/XML/Test/xmlts20130923.tar.gz

3) Execute:

$ tar xf libxml2-2.9.10.tar.gz

4) Execute:

$ cd libxml2-2.9.10/

5) Execute:

$ sed -i 's/test.test/#&/' python/tests/tstLastError.py

6) Execute:

$ export CPATH="/usr/include/python3.6/:$CPATH"

7) Execute:

$ sudo apt-get install -y python3-libxml2 python3-pip

8) Execute:

$ sudo pip3 install libxml2dom

9) Execute:

$ ./configure --prefix=/usr --disable-static --with-history --with-python=/usr/bin/python3 && make

Ensure here that the returning code ($?) is 0.

10) Execute:

$ tar xf ../xmlts20130923.tar.gz

11) Execute:

make check > check.log

Ensure here that the returning code ($?) is 0.

12) Execute:

$ sudo make install

Enjoy

$ xmllint data.xml -xpath "//some_child/ancestor::some_parent/attribute::id"                                                                               
 id="1"
 id="10010"
 id="10011"
 id="10020"
 id="10021"