Replace value in json files with variable values in shell script

Question

I am creating multiple files from a json template file and I need to replace two values in json file by different values which I am storing in variable. Below is how source json look like

Source :

{"parameters": [
            {
                "name": "dir_parm",
                "value": "changethis"
            }
        ],
        "targets": [
            {
                "identifier": "hsotchangethis"
            }
        ]

}

Output what I require:

"parameters": [
            {
                "name": "dir_parm",
                "value": "/apps"
            }
        ],
        "targets": [
            {
                "identifier": "iass02"
            }
      ]
   }

In this way json file has to be updated for directory and host name around 40-50 times.

Below is the sed command I tried but it is getting replaced. File name, hostname , directory all are variables\dynamic.

sed -i '/identifier/c\ \"identifier\" : '${bdhostnm}'/g' $fname

Note- I read we can use jq but in the organization it is not allowed. Any suggestion would be helpful

I am sorry, I mean sed command I used is not replacing host with the value in variable. It is either coming as empty or coming as bdhostnm — user19742249
– user19742249, Commented Aug 11, 2022 at 10:12
Have you tried using a tool, like jq, which is made especially for processing JSON? — Ted Lyngmo
– Ted Lyngmo, Commented Aug 11, 2022 at 10:29
@user19742249, In case you can install jq, then following could be helpful to you: jq '.parameters[].value |= "/apps" | .targets[].identifier |= "iass02"' Input_file — RavinderSingh13
– RavinderSingh13, Commented Aug 11, 2022 at 11:17

Haru Suzuki · Accepted Answer · 2022-08-18 06:09:49Z

3

As asked by user a sed solution:
Input

{"parameters": [
            {
                "name": "dir_parm",
                "value": "changethis"
            }
        ],
        "targets": [
            {
                "identifier": "hsotchangethis"
            }
        ]

}

value='/apps'  
bdhostnm='iass02'  
fname=file  
sed '/[ ]*"identifier":/{s/\("identifier": \)\(.*\)/\1'$bdhostnm'/g};/^[ ]*"value": /{s/\("value": \)\(.*\)/\1'${value/\//\\\/}'/g}' $fname

{"parameters": [
            {
                "name": "dir_parm",
                "value": /apps
            }
        ],
        "targets": [
            {
                "identifier": iass02
            }
        ]

}

edited Aug 18, 2022 at 6:09

answered Aug 12, 2022 at 17:40

Haru Suzuki

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3 Comments

user19742249 Over a year ago

This is not working as expected

user19742249 Over a year ago

I get message sed: -e expression #1, char 98: extra characters after command and values are not getting repalced.

Haru Suzuki Over a year ago

have you setted variables bdhosnm and value and fname

RavinderSingh13 · Accepted Answer · 2022-08-11 12:54:37Z

1

Since OP doesn't have jq and can't install jq so coming up with this awk solution. Which is written and tested in GNU awk. Here I have created 2 awk variables named valValue and valIdentifier where NEW values for respective(json) fields should be mentioned in them.

Here is the Online demo for used regex in following awk code.

awk -v valValue="/apps" -v valIdentifier="iass02" -v RS="" '
match($0,/^({"parameters": \[\n[[:space:]]+\
{\n[[:space:]]+"name": "dir_parm",\
\n[[:space:]]+"value": ")\
[^"]*("\n[[:space:]]+}\n\
[[:space:]]+\],\n[[:space:]]+\
"targets": \[\n[[:space:]]+\
{\n[[:space:]]+"identifier": ")\
[^"]*("\n[[:space:]]+}\n[[:space:]]+\
\]\n+[[:space:]]+})/,arr){
     print arr[1] valValue arr[2] valIdentifier arr[3]
}
'  Input_file

NOTE: In case someone wants a jq code for this one(though its clearly not a ask in question here), then try like: jq '.parameters[].value |= "/apps" | .targets[].identifier |= "iass02"' Input_file.

edited Aug 11, 2022 at 12:54

answered Aug 11, 2022 at 12:31

RavinderSingh13

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6 Comments

RavinderSingh13 Over a year ago

In case someone looking for one-liner form of awk code try like:

awk -v valValue="/apps" -v valIdentifier="iass02" -v RS="" 'match($0,/^({"parameters": \[\n[[:space:]]+{\n[[:space:]]+"name": "dir_parm",\n[[:space:]]+"value": ")[^"]*("\n[[:space:]]+}\n[[:space:]]+\],\n[[:space:]]+"targets": \[\n[[:space:]]+{\n[[:space:]]+"identifier": ")[^"]*("\n[[:space:]]+}\n[[:space:]]+\]\n+[[:space:]]+})/,arr){print arr[1] valValue arr[2] valIdentifier arr[3]}'  Input_file

user19742249 Over a year ago

value and target has to be modified as I have stored them in variables . json file has to be created for each target and value . When I try to valValue and valdentifier as variable , I am not getting results as expected.

RavinderSingh13 Over a year ago

@user19742249, both things could be done. Have awk like this:

awk -v valValue="$value" -v valIdentifier="$idenifier" -v RS="" 'match($0,/^({"parameters": \[\n[[:space:]]+{\n[[:space:]]+"name": "dir_parm",\n[[:space:]]+"value": ")[^"]*("\n[[:space:]]+}\n[[:space:]]+\],\n[[:space:]]+"targets": \[\n[[:space:]]+{\n[[:space:]]+"identifier": ")[^"]*("\n[[:space:]]+}\n[[:space:]]+\]\n+[[:space:]]+})/,arr){print arr[1] valValue arr[2] valIdentifier arr[3]}'  Input_file

I have virialized this program now, where value and identifier both are shell variables passed to awk. Run this.

RavinderSingh13 Over a year ago

@user19742249, continuing above comment here: Run this and see output on terminal once you are Happy we can save output into file, let me know how it goes.

RavinderSingh13 Over a year ago

@user19742249, you need to create shell variables then pass them to awk program just want to be clear here.

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