CODEWITHSUNDEEP
javapython
SVN600
SVN600

Reputation: 385

Java Process immediately exits

I am creating a Process as follows: 

Process p = Runtime.getRuntime().exec("nohup /usr/bin/python " + filePath + " &");
Process q = Runtime.getRuntime().exec("/usr/bin/python -m -webbrowser " + url);

I am trying to run the p in the background so that q can run without a problem. Also, when the Java program ends, the python script is no longer running.

Upvotes: 0

Views: 1085

Answers (3)

dimo414
dimo414

Reputation: 48824

The command you ran is nohup, and it did exit immediately. nohup started a separate Python process, but that's not the process p is controlling.

Why are you using nohup and & if that isn't the functionality you want? If you simply want to execute a Python subprocess just call:

Process p = Runtime.getRuntime().exec("/usr/bin/python " + filePath);

Note that it's also safer to use the overload of exec that takes an array, so you don't have to do string-concatenation yourself (and therefore avoid a type of security exploit). The syntax changes slightly to:

Process p = Runtime.getRuntime().exec(new String[]{"/usr/bin/python", filePath});

Or with ProcessBuilder:

Process p = new ProcessBuilder("/usr/bin/python", filePath).start();

Upvotes: 1

CodeJockNYC
CodeJockNYC

Reputation: 74

As Sean Bright mentioned take the '&' character out of the end of the script that you are running. Basically on all *nix systems. If you call make a type a command and use the ampersand, it will run that process in the background. That's why the call to java process is returning finished.

It would probably be better to not execute the command in the background (no '&') and just call Process.isAlive() periodically to determine if the process is finished.

Upvotes: 0

Athena
Athena

Reputation: 3228

Take a look at the documentation for the & operator here. Your process is running in the background. As far as the Java program you're writing (and the shell, for that matter) are concerned, the call you made has already ended. It's most certainly still running in the background, but you're telling the shell (and by extension your Java program) to not pay attention to the output and move on.

Upvotes: 0

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