如何从Java代码运行Linux程序

Question

I am trying to create a disk space from Java code using qemu-img so I instantiated process and runtime classes. When run the program the command is not executed though I used the same mechanism for similar execution and it work fine. So I am wondering whether I miss something here.

StringBuilder commandBuilder = new StringBuilder("qemu-img create -f "+chosenStorageType+" ~/"+storageName+".img "+storageSize+"M");
System.out.println(commandBuilder);
String command = commandBuilder.toString();
System.out.println("this is the correct one: "+command);

System.out.println("Creating the image...");
Runtime runtime = Runtime.getRuntime();
Process process = null;
try {
    process = runtime.exec(command);
    System.out.println("from process try..catch");
} catch (IOException e1) {
    e1.printStackTrace();
    System.out.println(e1.getMessage());
}finally{
    System.out.println("from finally entry");
    process.destroy();
}

the output is as following:

qemu-img create -f raw ~/testSPACE.img 23.0M

this is the correct one: /qemu-img create -f raw ~/testSPACE.img 23.0M
Creating the image...
from process try..catch
from finally entry

But if I go to the directory the file isn't created.

Just to test it if I copy the output into terminal everything works like a charm.

Answer 1

The tilde ( ~ ) here

" ~/"+storageName+".img "

is interpreted by the shell as meaning your home directory. I would substitute the real path.

Note also that you need to be consuming the process stdout/err , and collecting the error code of the process (and checking it!) via Process.waitFor()