Shell script call API via curl and process response

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": "[email protected]", "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": "[email protected]",
    "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!

Florian Schlag · Accepted Answer · 2020-05-08 07:43:08Z

6

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": "[email protected]", "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

edited May 8, 2020 at 7:43

answered May 21, 2019 at 7:15

Florian Schlag

6694 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Borgy Manotoy Over a year ago

I am having problem with regular expressions, please see regexr.com/4eccp I cannot extract just the value of token.

Florian Schlag Over a year ago

Try the following regex instead: "token":(\W+)?"\K[a-zA-Z0-9._]+(?="). The online tool you provided uses JavaScript regex syntax, grep uses Perl regex. Try this with regex101.com In addition: Be careful with posting JWT tokens here. It contains confidential information when pasted e.g. on jwt.io

Borgy Manotoy Over a year ago

If I hard code RESPONSE='<COPIED_RESPONSE_FROM_CURL_CALL>'... regular expression works. but if I use RESPONSE='<CURL_CALL>' it does not return anything (Token is blank).

Borgy Manotoy Over a year ago

It is really close, regexp works if I hard code the response.. but if I call curl... response looks correct... but regexp does not work.. it cannot return the token (empty/blank)

Florian Schlag Over a year ago

@PakiPat the closing single quote was missing. I edited my original post. Thanks!

|

Httqm · Accepted Answer · 2019-05-21 12:21:45Z

0

An alternate solution to parsing JSON with regex is jq :

echo '{ "user": { "id": 123, "token": "<GENERATED-TOKEN-HERE>", "email": "[email protected]", "refreshToken": "<GENERATED-REFRESH-TOKEN>", "uuid": "1239c226-8dd7-4edf-b948-df2f75508888" }, "clientId": "abc12345", "clientSecretKey": "thisisasecret" }' | jq -r '.user.token'

answered May 21, 2019 at 12:21

Httqm

8499 silver badges16 bronze badges

1 Comment

Borgy Manotoy Over a year ago

I am afraid Installing other command is not an option (jq) on my case

Collectives™ on Stack Overflow

Shell script call API via curl and process response

2 Answers 2

6 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related