Check null value in xml

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# 1  
Old 03-04-2013
Check null value in xml


I have a log file which is having some xml tags. I need to check the value for a particular xml field is null or not and if it is null i have to add current time as the value for that xml field.

I tried below code to check whether the word count is 0. But even if the xml field is null it is showing the count as 1.

if [ `cat Log.out | grep "<timestamp1>.*</timestamp1>" | wc -l` -gt 0 ]
echo timestamp is not empty

# 2  
Old 03-04-2013
What do you mean by "null"? Value "0" (zero) or empty field?
That .* means 0 or more occurrences of any char, so the word count will not equal 0 if that "<timestamp1> . . . </timestamp1>" occurs somewhere in your file.
Try <timestamp1>.+</timestamp1> or <timestamp1>..*</timestamp1> to discriminate empty fields.

And then - UUOC and UUOB.
grep -q "<timestamp1>.+</timestamp1>" Log.out && echo "found" || echo "empty/non existent"

will do.
# 3  
Old 03-04-2013
Hi RudiC

Thanks for the quick reply.

I meant the value is empty.

I tried with

and I am able to get the count if it having null values.

But if the log file is having an empty value for timestamp1 then i have to pull the entire xml and insert current time to that empty xml field.

Sample xml:

Could you please help me to do this.

Last edited by Neethu; 03-04-2013 at 05:52 AM..
# 4  
Old 03-04-2013
Following these fora for nearly half a year, you should be able to at least try a solution yourself. What would you come up with in the first place? We are happy to help should you get stuck...
# 5  
Old 03-04-2013
Hi RudiC,

I tried the following code
awk '/<submit>/,/<\/submit>/' log.out > xml
if [ -s xml ]
grep "<timestamp1>..*</timestamp1>" xml > tvalue
echo xml is empty

This will not pull any value if timestamp is empty in xml file. I want to check the value of timestamp1 in xml file and if it is empty i want to insert the current time. But in this code it is not pulling any xml tag.

Last edited by Neethu; 03-04-2013 at 06:53 AM..
# 6  
Old 03-04-2013
Fine so far.
and insert current time to that empty xml field.
What ideas do you have to insert the timestamp? Searching these fora might give you a head start...
# 7  
Old 03-04-2013
I noticed that in your code you are checking if your file size is empty, but if that is what you want, it is OK.

But if you are looking for a method to check if tag value is empty and insert current timestamp in it, then code something like:
awk -F'[<>]' ' BEGIN {
                cmd = "date +%Y%m%d%H%M%S"
} /<timestamp1>/ {
        if ( $3 == "" )
                cmd | getline dt
                $0 = "<timestamp1>" dt "</timestamp1>"
} 1 ' xml

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