Execute Windows commands from Java

Question

I try to use following command to execute a Windows command in a given directory.

try{
 String command = "cmd /c start cmd.exe";
 Process child = Runtime.getRuntime().exec(command);
 OutputStream out = child.getOutputStream();
 out.write("cd /d C:\\_private\\Files\\testfiles".getBytes());
 out.flush();
 out.write("for /f \"DELIMS=\" %x in ('dir /ad /b') do move \"%x*.*\" \"%x\\\"".getBytes());
 out.close();
}catch(IOException e){
}

It just open up a Command prompt in directory, where Java project is located.

• jhamon: Possible duplicate of Java Programming: call an exe from Java and passing parameters and https://stackoverflow.com/questions/6434009/java-runtime-getruntime-exec-cmd-with-long-parameters
• Andrew Thompson: See also When Runtime.exec() won't for many good tips on creating and handling a process correctly. Then ignore it refers to exec and use a ProcessBuilder to create the process. Also break a String arg into String[] args to account for things like paths containing space characters.

Answer 1

That process is already terminated. You only start cmd to start another cmd. That first cmd, to which you have a variable and to which you're writing is gone. Only the second one remains open.

Instead, start CMD only once and tell it to remain open:

String command = "cmd /k";

Next, please have a look on how to start programs with arguments.

Process process = new ProcessBuilder("cmd.exe", "/k").start();

• plaidshirt: I tried this way too, but file is not created: String[] cmd = {"\"cmd.exe\", \"/k\"", "cd /d C:\\_private\\Files\\myfiles", "copy NUL EMptyFile.txt"}; Process process = new ProcessBuilder(cmd).start();
• Thomas Weller: @plaidshirt That's not the right way. Just start cmd /k and do the rest (i.e. cd and copy) via OutputStream out