CODEWITHSUNDEEP
jsonbashshellshjq
JavaDeveloper
JavaDeveloper

Reputation: 5660

How to parse JSON in shell script?

I run the curl command $(curl -i -o - --silent -X GET --cert "${CERT}" --key "${KEY}" "$some_url") and save the response in the variable response. ${response} is as shown below

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Content-Length: 34
Connection: keep-alive
Keep-Alive: timeout=5
X-XSS-Protection: 1; 

{"status":"running","details":"0"}

I want to parse the JSON {"status":"running","details":"0"} and assign 'running' and 'details' to two different variables where I can print status and details both. Also if the status is equal to error, the script should exit. I am doing the following to achieve the task -

status1=$(echo "${response}" | awk '/^{.*}$/' | jq -r '.status')
details1=$(echo "${response}" | awk '/^{.*}$/' | jq -r '.details')
echo "Status: ${status1}"
echo "Details: ${details1}"
if [[ $status1 == 'error' ]]; then
    exit 1
fi

Instead of parsing the JSON twice, I want to do it only once. Hence I want to combine the following lines but still assign the status and details to two separate variables -

status1=$(echo "${response}" | awk '/^{.*}$/' | jq -r '.status')
details1=$(echo "${response}" | awk '/^{.*}$/' | jq -r '.details')

Upvotes: 3

Views: 7220

Answers (3)

Charles Duffy
Charles Duffy

Reputation: 295403

First, stop using the -i argument to curl. That takes away the need for awk (or any other pruning of the header after-the-fact).

Second:

{
  IFS= read -r -d '' status1
  IFS= read -r -d '' details1
} < <(jq -r '.status + "\u0000" + .details + "\u0000"' <<<"$response")

The advantage of using a NUL as a delimiter is that it's the sole character that can't be present in the value of a C-style string (which is how shell variables' values are stored).

Upvotes: 5

Kyle Banerjee
Kyle Banerjee

Reputation: 2784

As Benjamin already suggested, only retrieving the json is a better way to go. Poshi's solution is solid.

However, if you're looking for the most compact to do this, no need to save the response as a variable if the only thing your're going to do with it is extract other variables from it on a one time basis. Just pipe curl directly into:

curl "whatever" | jq -r '[.status, .details] |@tsv'

or 

curl "whatever" | jq -r '[.status, .details] |join("\t")'

and you'll get your values fielded for you.

Upvotes: 1

Poshi
Poshi

Reputation: 5762

You can use a construction like:

read status1 details1 < <(jq -r '.status + " " + .details' <<< "${response}")

You use read to assign the different inputs to two variables (or an array, if you want), and use jq to print the data you need separated by whitespace.

Upvotes: 1

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