Bash script for getting tag value

Question

Is there any way to get value(Yes or No) if i only have tag("answer_yes" or "answer_no") which are described in a xml file. I want to get them using bash.

<string tag="answer_yes" value="Yes"/>
<string tag="answer_no" value="No"/>

Answer 1

Use an XML-aware tool. For this simple query, xmllint is enough:

answer=answer_yes
xmllint --xpath "//string[@tag='$answer']/@value" file.xml | cut -f2 -d\"

It seems not to expand entities, though, so if your real strings contain quotes, you'll have to replace ", &, and < by ", &, and <, respectively.

xsh handles the entities for you:

xsh -aC 'open file.xml; $answer={$ARGV[0]};
         echo //string[@tag=$answer]/@value' "$answer"

Answer 2

To extract the value element of all strings with either tag="answer_yes" or tag="answer_no" in an XML document, XMLStarlet is an appropriate tool:

xmlstarlet sel -t -m '//string[@tag="answer_yes" or @tag="answer_no"]' -v '@value' -n

This will work in situations where naive regex-based approaches won't: It will recognize comments and CDATA as such and avoid trying to parse them; it will ignore answer_ content that isn't inside a string or a tag; it will recognize aliases brought in through your DTD; it will properly change & to & in output; it's agnostic to whether the tag or the value is given first in the element; it doesn't care about whether the whitespace separating the element from its attributes is tabs/spaces/newlines/etc; and so forth.

Answer 3

In sed if your Input_file is same as shown sample then following may help you in same.

sed 's/.*answer_//;s/".*//'  Input_file

Answer 4

regex='tag="answer_yes"[[:space:]]+value="([^"]+)"'

if [[ '<string tag="answer_yes" value="Yes"/>' =~ $regex ]] ; then
    echo "${BASH_REMATCH[1]}" ;
fi

Feel free to expand on the regex for more accurate matching.

Sources:

• http://mywiki.wooledge.org/BashGuide/Patterns?highlight=%28regex%29
• Capturing Groups From a Grep RegEx