Get comment tag from XML attribute with Bash

问题

I understand how to retrieve XML content within regular nodes, but I would like to understand how to retrieve content within a comment tag in XML using Bash.

For example, consider the below XML snippet:

    <ParentTag1><!--This comment is associated to ParentTag1 -->
       <ChildTag1>ChildTag1Blah</ChildTag1><!-- ChildTag1 comment-->
       <ChildTag2><!-- ChildTag2 comment -->
          <GrandchildTag1>GrandchildTag1Blah</GrandchildTag1><!-- GrandchildTag1 comment-->
          <GrandchildTag2>GrandchildTag2Blah</GrandchildTag2><!-- GrandchildTag2 comment-->
       </ChildTag2>
   </ParentTag1>

I'd like to know how to retrieve the comment associated to the node in question. For example, given ParentTag1, what command can I run to retrieve the "This comment is associated to ParentTag1" comment? Similarly for the other nodes.

I have used xmlstarlet in the past to retrieve content within the nodes, but I'm not entirely sure if the same would be used to retrieve content within a comment in XML.

回答1:

The retrieve comments, use the comment() node selector.
To get the "This comment is associated to ParentTag1" comment you can use

xmlstarlet sel -t -v "//ParentTag1/comment()[1]" input.xml

To chose from all descendant comments, use the descendant::comment() axis like this

xmlstarlet sel -t -v "//ParentTag1/descendant::comment()" input.xml

Result is:

This comment is associated to ParentTag1 
ChildTag1 comment
ChildTag2 comment 
GrandchildTag1 comment
GrandchildTag2 comment

After that, you can index the comment you want (or use another axis).

来源：https://stackoverflow.com/questions/58080572/get-comment-tag-from-xml-attribute-with-bash

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xml

bash

shell