Passing pre-escaped command-line arguments to ProcessBuilder

Question

I bumped into this problem today when setting up a local set of communicating programs. Basically one of my applications is sending some data to another, and part of this data is a string containing a command to execute (like you would from the command-line). Let's say, for example:

g++ foo.cc bar.cc -o foobar

is the command sent by my first application. The second application, which receives the command (amongst other things), needs to execute this command after doing some other processing.

Now, at first I thought this would be trivial using a ProcessBuilder :

String exampleCommand = "g++ foo.cc bar.cc -o foobar";
ProcessBuilder builder = new ProcessBuilder(exampleCommand);
builder.start().waitFor();

However this is where the problem occurs.

 CreateProcess error=2, The system cannot find the file specified

Okay, no worries I guess I can't just dump the whole thing into the builder. The first part of the command is usually a trivial string so I thought I could probably get away with a split around the first ' ' to separate the program name and arguments.

String exampleCommand = "g++ foo.cc bar.cc -o foobar";
String[] parts = exampleCommand.split(" ", 2);
ProcessBuilder builder = new ProcessBuilder(parts[0], parts[1]);
builder.start().waitFor();

And this brought me a little closer, the g++ file could now be found correctly, however after examining the stderr of g++ I found that the following error had occurred:

g++.exe: error: foo.cc bar.cc -o foobar: No such file or directory

At this point I realised that the ProcessBuilder class must be escaping all arguments passed to it in preparation for the command-line (hence the reason it usually takes arguments as an array of individual arguments rather than just a predefined argument string).

My question is, "Is there any way to pass a raw string of arguments to a ProcessBuilder and say THERE, execute EXACTLY this?"

Because the command comes from another application and is in no way static I can't just break the arguments down into an array beforehand and pass them to the ProcessBuilder constructor properly. The arguments are not so trivial that simply splitting the string around a ' ' will work properly either; arguments might contain spaces escaped with double quotes. For example:

g++ "..\my documents\foo.cpp" bar.cpp -o foobar

Could be a command coming from the application and splitting that string around ' ' and passing it to the ProcessBuilder will result in corrupt arguments.

If there is no proper way to do this can someone please point me to a standalone command line argument parser (in Java) that can turn a command-line string into a valid String[] ?

Answer 1

Okay I feel rather foolish now but I achieved my desired result by simply reverting back to the good old Runtime.getRuntime().exec(...) . I'll leave the question up in case anyone is as silly as me and find it useful.

String exampleCommand = "g++ foo.cc bar.cc -o foobar";
Runtime sys = Runtime.getRuntime();
sys.exec(exampleCommand);

Easy.

Answer 2

A comment to the Runtime.getRuntime().exec(...) solution:

The Runtime.getRuntime().exec(...) is not good anymore. In java executed on OSX El Capitan, 'Runtime.getRuntime().exec(...)' contains an error that sometimes closes the opened process when the java program exits. It works fine on previous OSX versions. However, ProcessBuilder works on all OSX versions.

(Haven't posted enough to have a enough rep points to make this as a normal comment.)