CODEWITHSUNDEEP
xmlawk
Adam Matan
Adam Matan

Reputation: 136341

Print XML element with AWK

How do I print the contents of an XML element - from the starting tag to the closing tag - using AWK?

For example, consider the following XML:

<flight>
    <airline>Delta</airline>
    <flightno>22</flightno>
    <origin>Atlanta</origin>
    <destination>Paris</destination>
    <departure>5:40pm</departure>
    <arrival>8:10am</arrival>
</flight>
<city id="AT"> 
       <cityname>Athens</cityname> 
       <state>GA</state>
       <description> Home of the University of Georgia</description>
       <population>100,000</population>
       <location>Located about 60 miles Northeast of Atlanta</location>
       <latitude>33 57' 39" N</latitude>
       <longitude>83 22' 42" W</longitude>
</city>

The desired output could be contents of the city element, from <city...> to </city>.

Upvotes: 3

Views: 7075

Answers (2)

Mark O&#39;Connor
Mark O&#39;Connor

Reputation: 77981

Solutions that parse XML with tools like awk and sed are imperfect. You cannot rely on XML always having a human readable layout. For example some web services will omit new-lines, resulting in the entire XML document appearing on one line.

I would recommend using xmllint, which has the ability to select nodes using XPATH, a query language designed for XML.

The following command will select the city tags:

xmllint --xpath "//city" data.xml

XPath is extremely useful. It makes the every part of the XML document addressable:

xmllint --xpath "string(//city[1]/@id)" data.xml

Returns the string "AT".

Poorly formatted XML data

This time return the first occurrence of the "city" tag. xmllint can also be used to pretty print the result:

$ xmllint --xpath "//city[1]" data.xml  | xmllint -format -
<?xml version="1.0"?>
<city id="AT">
  <cityname>Athens</cityname>
  <state>GA</state>
  <description> Home of the University of Georgia</description>
  <population>100,000</population>
  <location>Located about 60 miles Northeast of Atlanta</location>
  <latitude>33 57' 39" N</latitude>
  <longitude>83 22' 42" W</longitude>
</city>

data.xml

In this same data the first "city" tag appears all on one line. This is valid XML.

<data>
  <flight>
    <airline>Delta</airline>
    <flightno>22</flightno>
    <origin>Atlanta</origin>
    <destination>Paris</destination>
    <departure>5:40pm</departure>
    <arrival>8:10am</arrival>
  </flight>
  <city id="AT"> <cityname>Athens</cityname> <state>GA</state> <description> Home of the University of Georgia</description> <population>100,000</population> <location>Located about 60 miles Northeast of Atlanta</location> <latitude>33 57' 39" N</latitude> <longitude>83 22' 42" W</longitude> </city>
  <city id="DUB">
    <cityname>Dublin</cityname>
    <state>Dub</state>
    <description> Dublin</description>
    <population>1,500,000</population>
    <location>Ireland</location>
    <latitude>NA</latitude>
    <longitude>NA</longitude>
  </city>
</data>

Upvotes: 5

Ed Morton
Ed Morton

Reputation: 203899

$ awk -v tag='city' '$0~"^<"tag"\\>"{inTag=1} inTag; $0~"^</"tag">"{inTag=0}' file
<city id="AT">
       <cityname>Athens</cityname>
       <state>GA</state>
       <description> Home of the University of Georgia</description>
       <population>100,000</population>
       <location>Located about 60 miles Northeast of Atlanta</location>
       <latitude>33 57' 39" N</latitude>
       <longitude>83 22' 42" W</longitude>
</city>

Using GNU awk above for \> word boundary functionality. With other awks use [^[:alnum:]_] or similar.

To only print the first occurrence:

$ awk -v tag='city' '$0~"^<"tag"\\>"{inTag=1} inTag{print; if ($0~"^</"tag">") exit}' file
<city id="AT">
       <cityname>Athens</cityname>
       <state>GA</state>
       <description> Home of the University of Georgia</description>
       <population>100,000</population>
       <location>Located about 60 miles Northeast of Atlanta</location>
       <latitude>33 57' 39" N</latitude>
       <longitude>83 22' 42" W</longitude>
</city>

Upvotes: 2

Related Questions