Shell script call API via curl and process response - shell

Question

I need to create a shell script that calls my login API via curl.
The script should be able to store and process the response from curl api call.
myscript.sh
#!/bin/bash
echo "Extract bearer token from curl calling login api"
echo
# Check cURL command if available (required), abort if does not exists
type curl >/dev/null 2>&1 || { echo >&2 "Required curl but it's not installed. Aborting."; exit 1; }
echo
PAYLOAD='{"email": "dummy-user#acme.com", "password": "secret"}'
curl -s --request POST -H "Content-Type:application/json" http://acme.com/api/authentications/login --data "${PAYLOAD}"
My problem in the given script is:
it does not get the response of curl calling the API.
From the response json, get only the token value.
Sample Login API response:
{
"user": {
"id": 123,
"token": "<GENERATED-TOKEN-HERE>",
"email": "dummy-user#acme.com",
"refreshToken": "<GENERATED-REFRESH-TOKEN>",
"uuid": "1239c226-8dd7-4edf-b948-df2f75508888"
},
"clientId": "abc12345",
"clientSecretKey": "thisisasecret"
}
I only need to get the value of token and store it in a variable... I will use token value in other curl api call as bearer token.
What do I need to change in my script to extract the token value from the response of curl api call?
Thanks!

Answer 1

Your curl statement has an error in it. You are executing it with the target URL as an header field:
curl --request POST -H "Content-Type:application/json" -H http://acme.com/api/authentications/login --data "${PAYLOAD}"
^
|
Remove this header flag
Also the silent -s flag helps when curl is executed from scripts:
-s, --silent
Silent or quiet mode. Don't show progress meter or error messages. Makes Curl mute.
Afterwards you could store the data in a variable and execute a regular expression on it to extract the token you need for further processing.
The complete script could look like the following:
#!/bin/bash
echo "Extract bearer token from curl calling login api"
echo
# Check cURL command if available (required), abort if does not exists
type curl >/dev/null 2>&1 || { echo >&2 "Required curl but it's not installed. Aborting."; exit 1; }
echo
PAYLOAD='{"email": "dummy-user#acme.com", "password": "secret"}'
RESPONSE=`curl -s --request POST -H "Content-Type:application/json" http://acme.com/api/authentications/login --data "${PAYLOAD}"`
TOKEN=`echo $RESPONSE | grep -Po '"token":(\W+)?"\K[a-zA-Z0-9._]+(?=")'`
echo "$TOKEN" # Use for further processsing

Answer 2

An alternate solution to parsing JSON with regex is jq :
echo '{ "user": { "id": 123, "token": "<GENERATED-TOKEN-HERE>", "email": "dummy-user#acme.com", "refreshToken": "<GENERATED-REFRESH-TOKEN>", "uuid": "1239c226-8dd7-4edf-b948-df2f75508888" }, "clientId": "abc12345", "clientSecretKey": "thisisasecret" }' | jq -r '.user.token'