Postman - How do I call a shell script and assign to a var?

Question

I have a simple shell script that I'd like to run in the background and have it be assigned to a Postman global variable. Any ideas of how to do this with Postman?

Answer 1

Setting dynamic variable via external script.

Postman can only trigger HTTP request, So there is no direct way we can execute script such as .sh script. But you can run a local server (here node js server) and write a node js script to execute a shell script or other executable files Now let do that In step by step

Step 1: Define Your Task

I have a PHP script that provide me with the token. This token will be later used in API request. This script looks something like this which is saved as TokenGenerato.php

<?php
require "vendor/autoload.php";

class TokenGeneration {

    public  $appID= "50A454F3-EE11-4A4C-B708-965BC7640C08";
    public $token = NULL; 

    public function __construct(){
        //echo "\n URL: ".$this->url;
        $this->token = $this->generateAppToken();
    }

    function generateAppToken(){
        $message =   $this->appID."~REQUEST".time();
        //echo "\n message: ".$message;

        $cryptor = new \RNCryptor\RNCryptor\Encryptor;
        $base64Encrypted = $cryptor->encrypt($message, $this->appID);
        //echo "\n token: ". $base64Encrypted;
        return $base64Encrypted;
    }
}
?>

Step 2: Get your token

We will write token.php program to get token from TokenGenerato.php

<?php
  require "TokenGeneration.php";
  $tokengen = new TokenGeneration();
  echo $tokengen->token;
?>

we can run this php script via

php token.php

Output:

AwFmHNkA1HdM1VHFadu89nE3xZuKO3pLQ7cHOrCj2x2WZoSt

Step 3: Create Node js script.

You can use chile_process module to execute shell command in node js. Tutorial on child_process

Create node js script in token.js with following code

const http = require('http'), { exec } = require('child_process');

http.createServer((req, res) => {
  // Give the path of your bat or exe file
  exec('php token.php', (err, stdout, stderr) => {
    console.log({ err, stdout, stderr });

    if (err) {
      return res.writeHead(500).end(JSON.stringify(err));
    }

    // Output of the script in stdout
    return res.writeHead(200).end(stdout);
  });
}).listen(8000);
console.log('Server running at http://127.0.0.1:8000/');

Next start the node server with the following command

node token.js

Step 4: Pre-Request Script for Postman.

First create the new API request in postman, then select Pre-request Script and write following code to send http request before the actual API call happens and save the response in local variable.

pm.variables.set("password", "AwErFEinDqiOvXFx2wVgHvt+Rpo0jdoTH0D0QldS");

console.log("password: ", pm.variables.get("password"));

pm.sendRequest('http://127.0.0.1:8000', (err, response) => {
    // This will have the output of your batch file
    console.log(response.text());
    pm.variables.set("token", response.text());
})

Finally, prepare the header to use token

token = {{token}}