[FIXED] running Echo from Java

Issue

I'm trying out the Runtime.exec() method to run a command line process.

I wrote this sample code, which runs without problems but doesn't produce a file at c:\tmp.txt.

String cmdLine = "echo foo > c:\\tmp.txt";
Runtime rt = Runtime.getRuntime();
Process pr = rt.exec(cmdLine);

BufferedReader input = new BufferedReader(
                           new InputStreamReader(pr.getInputStream()));
String line;

StringBuilder output = new StringBuilder();
while ((line = input.readLine()) != null) {
    output.append(line);
}

int exitVal = pr.waitFor();

logger.info(String.format("Ran command '%s', got exit code %d, output:\n%s", cmdLine, exitVal, output));

The output is

INFO 21-04 20:02:03,024 - Ran command 'echo foo > c:\tmp.txt', got exit code 0, output: foo > c:\tmp.txt

Solution

echo is not a standalone command under Windows, but embedded in cmd.exe.

I believe you need to invoke a command like "cmd.exe /C echo ...".

Answered By - Thorbjørn Ravn Andersen
Answer Checked By - David Marino (JavaFixing Volunteer)