json - REGEX reformatting

Question

I am trying to reformat a json file and eliminate a good portion of the file. Here is the original json file.

       "2597401":[{"jobID":"2597401",
                 "account":"TG-CCR120014",
                 "user":"charngda",
                 "pkgT":{"pgi/7.2-  5":{"libA":["libpgc.so"],
                 "flavor":["default"]}},          
                 "startEpoch":"1338497979",
                 "runTime":"1022",
                 "execType":"user:binary",              
                 "exec":"ft.D.64",
                 "numNodes":"4",
                 "sha1":"5a79879235aa31b6a46e73b43879428e2a175db5",
                 "execEpoch":1336766742,
                 "execModify":"Fri May 11 15:05:42 2012",
                 "startTime":"Thu May 31 15:59:39 2012",
                 "numCores":"64",
                 "sizeT":{"bss":"1881400168","text":"239574","data":"22504"}},  
                 {"jobID":"2597401",
                 "account":"TG-CCR120014",
                 "user":"charngda",
                 "pkgT":{"pgi/7.2-5":{"libA":["libpgc.so"],
                 "flavor":["default"]}},
                 "startEpoch":"1338497946",
                 "runTime":"33"  "execType":"user:binary",
                 "exec":"cg.C.64",
                 "numNodes":"4",
                 "sha1":"caf415e011e28b7e4e5b050fb61cbf71a62a9789",
                 "execEpoch":1336766735,
                "execModify":"Fri May 11 15:05:35 2012",
                "startTime":"Thu May 31 15:59:06 2012",
                "numCores":"64",
                "sizeT":{"bss":"29630984","text":"225749","data":"20360"}},
                {"jobID":"2597401",
                "account":"TG-CCR120014",
                "user":"charngda",
                "pkgT":{"pgi/7.2-5":  {"libA":["libpgc.so"],
                "flavor":["default"]}},
                "startEpoch":"1338500447",
                "runTime":"145",
                "execType":"user:binary",
                "exec":"mg.D.64",
                "numNodes":"4",
                "sha1":"173de32e1514ad097b1c051ec49c4eb240f2001f",
                "execEpoch":1336766756,
                "execModify":"Fri May 11 15:05:56 2012",
                "startTime":"Thu May 31 16:40:47 2012",
                "numCores":"64",
                "sizeT":{"bss":"456954120","text":"426186","data":"22184"}},{"jobID":"2597401",
                "account":"TG-CCR120014",
                "user":"charngda",
                "pkgT":{"pgi/7.2-5":{"libA":["libpgc.so"],
                "flavor":["default"]}},
                "startEpoch":"1338499002",
                "runTime":"1444",
                "execType":"user:binary",
                "exec":"lu.D.64",
                "numNodes":"4",
                "sha1":"c6dc16d25c2f23d2a3321d4feed16ab7e10c2cc1",
                "execEpoch":1336766748,
                "execModify":"Fri May 11 15:05:48 2012",
                "startTime":"Thu May 31 16:16:42 2012",
                "numCores":"64",
                "sizeT":{"bss":"199850984","text":"474218","data":"27064"}}],

For each JobId I only want to keep the "exec" field and the JobID. How can I construct a regex to dumb the rest of the data? Ideally, I want the following: JobID exec1 exec2 exec3
Is there some way to do this?

Thanks in advance.

Answer 1

Because you did not specify your RegEx engine, I will assume you are using pcre for my answer.

Based on JSON formatting, you can use this RegEx to match unneeded key-value pairs to replace with nothing:

/(,s*(*SKIP))?+("(?!jobID"|exec)[^"]+"s*+:s*+("[^"]*"|{(?2)?+(?>,s*(?2))*}|[(?3)?+(?>,s*(?3))*]))(?(1)|,?)/g

Here is what you ordered after applying the RegEx replacement:

       "2597401":[{"jobID":"2597401",
                 "execType":"user:binary",              
                 "exec":"ft.D.64",
                 "execEpoch":1336766742,
                 "execModify":"Fri May 11 15:05:42 2012"},  
                 {"jobID":"2597401"  "execType":"user:binary",
                 "exec":"cg.C.64",
                 "execEpoch":1336766735,
                "execModify":"Fri May 11 15:05:35 2012"},
                {"jobID":"2597401",
                "execType":"user:binary",
                "exec":"mg.D.64",
                "execEpoch":1336766756,
                "execModify":"Fri May 11 15:05:56 2012"},{"jobID":"2597401",
                "execType":"user:binary",
                "exec":"lu.D.64",
                "execEpoch":1336766748,
                "execModify":"Fri May 11 15:05:48 2012"}],

As you can see, the resulting string has invalid syntax within '"jobID":"2597401" "execType":"user:binary"', which was a syntax error in your given data...

With explanation:

/(,s*(*SKIP))?+
# Attempts to match a comma and whitespace,
# without backtracking;
# And if the comma is matched, use (*SKIP) verb,
# which advances the pointer if we fail to match the comma.

# Key - Value pairs not worthy of keeping.
(
  "(?!jobID"|exec)[^"]+" # Check if we like this key.
  s*+:s*+ # The colon, advance whitespaces.
  ( # Check keys recursively.
    "[^"]*"
      # String literals, boring.
    | {(?2)?+(?>,s*(?2))*}
      # Or: An object storing some key-value pairs
      # we don't care about.
    | [(?3)?+(?>,s*(?3))*]
      # Or: An array storing some values
      # we don't care about.
  )
)
(?(1)|,?)
# Balance the comma (so the result string is still valid JSON)
/gx

Here is a regex demo.