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.

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 — jhamon
– jhamon, Commented Jul 26, 2018 at 13:29
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. — Andrew Thompson
– Andrew Thompson, Commented Jul 26, 2018 at 23:30

Thomas Weller · Accepted Answer · 2018-07-26 13:32:23Z

3

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();

answered Jul 26, 2018 at 13:32

Thomas Weller

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2 Comments

plaidshirt Over a year ago

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 Over a year ago

@plaidshirt That's not the right way. Just start cmd /k and do the rest (i.e. cd and copy) via OutputStream out

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