How to get the JSON STRING from the given string

Question

I have a string given below. I just need to get the first accountHeader (bolded) JSON string.

<START AdditionalInfo#:>[FormsGenerationServiceImpl::,  accountNumber:ABC07667 ,  [Source System Request  : {"Info":{"Holder": {"nameData": {"shortName": "McIntosh"}},**"accountHeader": {"a": "Y","b": "1","c": "4","draft": "P","e": "Y0000DU9","f": "T","g": "1"}**,"forms": {"maskSSN": "N","deliverForms": "G","selectedForms": {"T5": ["F10"],"T1": ["F1403"],"T2": ["F100001401"]}},"accountHeader": {"a": "Y","b": "1","c": "4","d": "HWA","draftRequestType": "P","e": "Y0000DU9","f": "T","g": "1"}}} ], null]<AdditionalInfo#: END>

My output should be

"accountHeader": {"a": "Y","b": "1","c": "4","draft": "P","e": "Y0000DU9","f": "T","g": "1"}

Answer 1

Here are a few options:

1. Use grep with the -o flag to print only the matching part of the line and filter with head to get the first match only:

   grep -o '"accountHeader[^}]*}' file.json | head -n1 
   

   The regular expression looks for a "accountHeader then as many as possible non-} characters until the first }. It's basically the same regex used in the other solutions below as well.

2. Use sed with -n to suppress printing and p after the substitution to print only if the substitution was a success. Then, substitute (remove) everything but what you want:

   sed -n  's/.*\("accountHeader[^}]*}\).*/\1/p' file.json 
   

3. Use Perl, the -l adds a newline to each print call, the -n means "process each line of the input file" and apply the script given by -e:

   perl -lne  '/.*("accountHeader[^}]*})/ && print $1' file.json 
   

4. Use awk, this assumes that the ** in your example input are there to highlight the part you're interested in and don't actually exists in the real data. If so, this should work:

   awk -F'},' '{print $2"}"}' file.json
   

---

If the ** are actually there, things are even simpler, just use them as field delimiters:

awk -F'**' '{print $2"}"}' file.json

or

perl -F"\*\*" -alne 'print $F[1]' file.json