PowerShell command not getting executed using java Process class. While all other commands are working fine

Question

I am trying to execute below command using java Process class but it's not giving me any response or neither its effecting which it should do.

But when I am executing the command directly on PowerShell its working fine only it's not working using java code. I have tried other PowerShell commands, and all are working fine accept this one.

It's a command to disable indexing of a drive.

Output its only printing the command and in response of isAlive() method call it replies with false.

Command: powershell.exe Get-WmiObject -Class Win32_Volume -Filter "DriveLetter='I:'" | Set-WmiInstance -Arguments @{IndexingEnabled=$False} powershell.exe Get-WmiObject -Class Win32_Volume -Filter "DriveLetter='I:'" | Set-WmiInstance -Arguments @{IndexingEnabled=$False}

isAlive: false

There is nothing more in the code I am just calling this method from my main class that's it like classObject.disableIndexing("D")

Note I am executing the same using admin rights only. Please help.

public String disableIndexing(String driveLetter) {
        
    String returnVal="";
    String command = "powershell.exe Get-WmiObject -Class Win32_Volume -Filter \"DriveLetter='"+driveLetter+":'\" | Set-WmiInstance -Arguments @{IndexingEnabled=$False} ";
    try {   
        System.out.println(command);
        Process p = Runtime.getRuntime().exec(command);
        p.waitFor();
        String line1="";
        String line="";
        BufferedReader br=new BufferedReader(new InputStreamReader(p.getInputStream()));
        while ((line1 = br.readLine()) != null) {
                    System.out.println(line1);
            if(!line1.isEmpty())
            System.err.println(line1);
        }
        System.out.println(p.isAlive());
        if(p.exitValue()==0) {
            returnVal="Indexing changed Successfully";
                }else {
            returnVal="Your Drive is Not Responding Try After Some Time";
            }
    }catch(Exception e) {
        e.printStackTrace();
            
    }
    return returnVal;
        
}

Answer 1

The problem here is likely that | is interpreted by the default shell (eg. cmd.exe) before being passed to powershell.exe .

To work around this, use the -EncodedCommand command line switch to safely pass the command to powershell.exe :

public String disableIndexing(String driveLetter) {
    String driveLetter = "D";
    String powerShellCommand = "Get-WmiObject -Class Win32_Volume -Filter \"DriveLetter='" + driveLetter + ":'\" | Set-WmiInstance -Arguments @{IndexingEnabled=$False}";

    // Base64-encode the UTF16LE representation of the command
    byte[] powerShellBytes = powerShellCommand.getBytes(StandardCharsets.UTF_16LE);
    String encodedCmd = new String(Base64.getEncoder().encode(powerShellBytes));

    String command = "powershell.exe -EncodedCommand " + encodedCmd;

    try {
        // proceed the same as before ...
    }
    catch (Exception e) {
        // ...
    }

    return returnVal;
}

Answer 2

hey guys I got the solution. But even I didn't understand how this worked. So, what I did is while coping my command from one method to another method I accidently left the 2 extra slashes on my String command and executed it. And it worked. Actual Command: String command = "powershell.exe Get-WmiObject -Class Win32_Volume -Filter \"DriveLetter='H:'\" | Set-WmiInstance -Arguments @{IndexingEnabled=$False} " It was not working.

Command which worked: String command = "powershell.exe Get-WmiObject -Class Win32_Volume -Filter \\\"DriveLetter='H:'\\\" | Set-WmiInstance -Arguments @{IndexingEnabled=$False} " I still not able to understand how it worked. because in actual PowerShell command it shouldn't have that back slash before and after DriveLetter.