We help IT Professionals succeed at work.

awk - xml parsing

987 Views
Last Modified: 2012-05-10
I wanted to print the tag name after <Transaction> in the attached file. That is I wanted to print "AirAvailability_12". I did the following

awk '
BEGIN {
FS="[<>]";
n=0;
}
{
   if ( $2 == "Transaction") n=1;
   if ( n == 2 ) {
   print $2;
   exit;
   }
   if ( n == 1) n++;
}'

This works in s.txt  but not s1.txt (both files attached).

Any thoughts? Appreciate if someone points something I am missing.
s.txt
s1.txt
Comment
Watch Question

Author

Commented:
s.txt and s1.txt have the same contents. Only formatting differs.
CERTIFIED EXPERT
Most Valuable Expert 2013
Top Expert 2013

Commented:
That's because in s1.txt there is no linefeed between >Transaction> and <AirAvailability_12>.

You'll have to do something like

awk '{FS="[<>]"; if($6 == "Transaction") print $8}' s1.txt

Author

Commented:
I am sorry but I do not see any output when I execute

awk '{FS="[<>]"; if($6 == "Transaction") print $8}' s1.txt
CERTIFIED EXPERT
Most Valuable Expert 2013
Top Expert 2013
Commented:
This one is on us!
(Get your first solution completely free - no credit card required)
UNLOCK SOLUTION
CERTIFIED EXPERT
Distinguished Expert 2019

Commented:
To make the awk script uniform, you should convert the single line XML file s1.txt into one matching s.txt.
I.e. create a perl script that will go and reformat the xml file that is being fed into a common format.  I.e. you define which types of entries must be on a line by them selves, which entries have the open value close. etc.

Are there multiple processes that generate these XML files.

IMHO it is easier to make the input file have uniform layout versus trying to come up with a script that will match any variation.

Commented:
May a propose a different approach than awk?

xpath will deliver the first element after Transaction (with all it's childs), so cut out the first shown element and you have the name of the element directly following Transaction, and it does not matter how the XML is formatted, or how often Transaction is in the HTML:

xpath file.xml "//Transaction/*[1]" 2>/dev/null | sed -e 's/^<\([^>]*\)>.*/\1/g'

Open in new window

explanation:
"//Transaction/*[1]"  <- Xpath query to select the first element after all Transaction elements

2>/dev/null <- Xpath has some additional output on stderr, eliminate it

sed -e  's/^<\([^>]*\)>.*/\1/g' <- cut aut the first element to display it


xpath should be available or easily installable on any unix
best
Ray

Author

Commented:
arnold - Yes, the XML needs to be formatted so the script works. Unfortunately the XML are always in the s1.txt format. To be on the safer side, I have slightly modified woolmilkporc code as below. This works for both s.txt and s1.txt.

awk '
BEGIN {
FS="[<>]"
}
{
for (i=1;i<=NF;i++) {
 if ($i != "") {
  if ($i == "Transaction") {
  j=1
  continue
  }
  if (j==1) {
  print $i
  exit
  }
 }
}
}'

Thanks woolmilkporc.

hatrix76 - Thanks for the suggestion. Unfortunately I do not have xpath installed in our servers. Requested the admin to do so. Until then I have to go with the awk variant.
Unlock the solution to this question.
Join our community and discover your potential

Experts Exchange is the only place where you can interact directly with leading experts in the technology field. Become a member today and access the collective knowledge of thousands of technology experts.

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.