I'm trying to run a system command to extract a tar.bz2 file to a specified directory. This is the code:
ProcessBuilder myProc = new ProcessBuilder("tar", "-xjf", "/path/to/MyTarFile.tar.bz2");
myProc.directory(new File("/directory/i/want/results/in/"));
myProc.start();
System.out.println(myProc.command());
It runs without error, however the file is deleted and not extracted anywhere.
Any help would be greatly appreciated.
I know Runtime.exec() has a really nasty feature where if you don't manually drain STDOUT/STDERR, it effectively appears to hang. I would hope that ProcessBuilder corrected that deficiency, but this page includes this tidbit:
A word of caution about the examples in this tip. It is possible that the examples will deadlock if the subprocess generates enough output to overflow the system. A more robust solution requires draining the process stdout and stderr in separate threads.
So, make sure you're handling Process.getInputStream() and Process.getErrorStream(), as I recommended in the comments; it could solve the problem outright!
myProc.redirectErrorStream(true), which redirects standard error into standard output and gets rid of the need for a separate thread.Change the myProc.start(); line to
Process p = myProc.start();
p.waitFor();
That will make sure your program doesn't exit until the tar is finished.
Run this to see errors. Perhaps one of your paths is incorrect.
import java.io.File;
import java.io.InputStream;
public class Untar {
public static void main(String[] args) throws Exception {
ProcessBuilder myProc = new ProcessBuilder("tar", "-xjf", "foo.tar.bz2");
myProc.directory(new File("newdir"));
Process p = myProc.start();
InputStream is = p.getErrorStream();
int c;
while( (c = is.read()) != -1 ){
System.out.print((char)c);
}
p.waitFor();
System.out.println(myProc.command());
}
}
Just tried this code. It works.
Check your paths.
