How to Use Curl in Java

How to use cURL in Java?

You can make use of java.net.URL and/or java.net.URLConnection.

URL url = new URL("https://stackoverflow.com");

try (BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"))) {
    for (String line; (line = reader.readLine()) != null;) {
        System.out.println(line);
    }
}

Also see the Oracle's simple tutorial on the subject. It's however a bit verbose. To end up with less verbose code, you may want to consider Apache HttpClient instead.

By the way: if your next question is "How to process HTML result?", then the answer is "Use a HTML parser. No, don't use regex for this.".

Java executing curl command not working on some commands

I made a minimal example to explain you a few things:

public class Playground {
    public static void main(String... args) throws IOException, InterruptedException {
        String cmdGetDocId = "curl -XGET 'https://google.com'";
        Process process = Runtime.getRuntime().exec(cmdGetDocId);
        InputStream inputStream = process.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        System.out.println("output: ");
        Thread.sleep(2000);
        while(process.isAlive()) Thread.sleep(100);
        System.out.println("return value: " + process.exitValue());
        reader.lines().forEach(System.out::println);
        reader = new BufferedReader(new InputStreamReader(process.getErrorStream()));
        reader.lines().forEach(System.err::println);
        System.out.println("---");
    }
}

On the one hand, you must make sure, the command is actually finished, when you try to output. In order to make sure, I have this dirty while-loop. Also, you want to have a look at the Error-Output, too.

Also you actually don't want to use cURL inside of your Java Program. There is a ton of beautiful Libraries or even the bare HttpURLConnection.

How to run a curl command from java?

You can do it like this

    String branchName="name";
    String branchId="bid";
    String sourceBranch="sb"
    String alias="ppp"

   String[] command = {"curl" "-k" "-i" "-X" POST "-H" "Content-Type: multipart/form-data" --cookie "rsession=your rsession" "Content-Type:application/json" --data{branchName+":"+branchId":"+sourceBranch":",+alias}};
    ProcessBuilder process = new ProcessBuilder(command); 
    Process p;
    try
    {
        p = process.start();
         BufferedReader reader =  new BufferedReader(new InputStreamReader(p.getInputStream()));
            StringBuilder builder = new StringBuilder();
            String line = null;
            while ( (line = reader.readLine()) != null) {
                    builder.append(line);
                    builder.append(System.getProperty("line.separator"));
            }
            String result = builder.toString();
            System.out.print(result);

    }
    catch (IOException e)
    {   System.out.print("error");
        e.printStackTrace();
    }

Execute Curl from Java

In 'command', try removing the single quotes from

"'admin2:0xdRv63RKq2MtA326BNGQAI6yA1QNGO09enamGxI'"

so that it becomes

"admin2:0xdRv63RKq2MtA326BNGQAI6yA1QNGO09enamGxI"

and see if that helps. It might be considering them as part of the actual username and password.

I think the issue is the Json in this case and I think you are right then that the double quotes are the issue. Try putting the Json in a file and use curl to send the file contents as the body of your message.

String[] command = {"curl", "-k", "-v", "-u","admin2:0xdRv63RKq2MtA326BNGQAI6yA1QNGO09enamGxI",
            "-d", "@/path/to/filename.json", "-H", "Content-Type: application/json", "https://192.168.101.59/api/v1/auth/"};

Java executing curl command using HttpURLConnection returns 204 (HTTP_NO_CONTENT)

Did you try, setting the same user agent in your Java Code, cURL would use? something like curl/7.37.0?
As far as I can tell, that should be all, what differs. Aside cURL following redirects. But as there is no redirect, I guess it might be the User Agent making a difference.

There are a lot of server applications, behaving differently, when they are called by a browser (Like you make it think by setting the User-Agent to Mozilla/5.0), instead of some other application, like cURL.

How to Use Curl in Java