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Parsing and Editing a json file with bash script

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# 1  
Old 04-20-2016
Parsing and Editing a json file with bash script
I am trying to automate editing of a json file using bash script.

The file I initially receive is

Code:
{
  "appMap": {
    "URL1": {
      "name": "a"
    },
    "URL2": {
      "name": "b"
    },
  "URL3": {
      "name": "c"
    },
}

WHat I would like to do is replace URL1,URL2,URL3 with URL4,URL5,URL6.

I do not want to use a sed command like:

Code:
sed -i "s/URL1/URL4/g" <file>

But I want to parse through it and change values based on "name".

Is this something that is possible using bash ? Or do I need to look into perl or python ?
# 2  
Old 04-20-2016
Hello Juniad Subhani,

Could you please try following and let me know if this helps.
Code:
perl -pi -e 's/URL1/URL4/g;s/URL2/URL5/g;s/URL3/URL6/g'  Input_file

Wanted to add here this will change Input_file with the new values.

Thanks,
R. Singh
# 3  
Old 04-20-2016
Some more/refined details, please! I guess you don't want to modify based on "name" (the constant string), but on name's value, i.e. "a", "b", or "c", and all of this just in the "appMap" section?
# 4  
Old 04-20-2016
Hello RudiC,

Yes its more like if "name" is "a" , use URL4
If "name" is "b", use URL5
If "name" is "c", use URL6
# 5  
Old 04-20-2016
Here is an awk approach:-
Code:
awk -F'[" ]' '
        BEGIN {
                A["a"] = "URL4"
                A["b"] = "URL5"
                A["c"] = "URL6"
        }
        /URL/ {
                s = $0
                getline
                if ( $(NF-1) in A )
                        sub( /URL[0-9]+/, A[$(NF-1)], s )
                print s
        }
        1
' file.json

# 6  
Old 04-20-2016
Well, although a parser is not simply done but usually an intricate piece of software, here is
- a bash script
- replacing ALL kind of URLs (abc.com; def.org; ghi.de; ...)
- only in "appMar" section
As the URL can assume any shape, we can't rely on a string constant ("URLnn") but need to check for the file structure (the URL is the first entry in the second nesting level).

Try
Code:
#!/bin/bash
#
TGSCT=0
LEVEL=0
URL=""

declare -A RP
RP["a"]=XYZ.com                                         # set up replacement URLs
RP["b"]=YZX.org
RP["c"]=ZXY.biz

while IFS="" read LN                                    # don't destroy original line
 do     IFS=": " read P1 P2 R <<< $LN                   # get elements from line; use bashs "here string"
        [ "$P1" != "${P1/appMap}" ] && TGSCT=1          # test for the right target section ("appMap")

        OLDLVL=$LEVEL                                   # save nesting level
        T1=${LN//\{}                                    # compute actual nesting level (based on braces)
        T2=${LN//\}}
        LEVEL=$((LEVEL + ${#T2} - ${#T1}))              # which is count opening braces minus count closing braces

        [ "$TGSCT" -eq 0 ] &&   { echo "$LN"
                                  continue
                                }                       # not in right section: print and leave

        [ "$OLDLVL" -eq 2 ] &&  { URL=${P1//\"}         # test for nesting level (URL is 2), compute URL w/o double quotes
                                  TMP="$LN"             # save URL in variable and total line in temp. var
                                }

        [ "$P1" != "${P1/name}" ] && {  NM=${P2//\"}    # test for "name" tag, compute name value w/o double quotes
                                        LN="${TMP/$URL/${RP[$NM]}}"$'\n'"$LN"
                                                        # replace old URL with new URL
                                        URL=""; }       # empty URL variable

        [ -z "$URL" ] && echo "$LN"                     # print only if no URL has been intercepted

        [ "$LEVEL" -eq 0 ] && TGSCT=0                   # zero nesting level means target section left

   done < file                                          # read from json file

This is just straightforward functionality to prove it's working, there's nothing extra like error checking or debugging. If need be, this is left to the reader.
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