Question

How do I run multiple commands in SSH using Java runtime?

the command: ssh user@127.0.0.1 ‘export MYVAR=this/dir/is/cool; /run/my/script
/myscript; echo $MYVAR’

@Test
  public void testSSHcmd() throws Exception
  {
    StringBuilder cmd = new StringBuilder();

    cmd.append("ssh ");
    cmd.append("user@127.0.0.1 ");
    cmd.append("'export ");
    cmd.append("MYVAR=this/dir/is/cool; ");
    cmd.append("/run/my/script/myScript; ");
    cmd.append("echo $MYVAR'");

    Process p = Runtime.getRuntime().exec(cmd.toString());
  }

The command by its self will work but when trying to execute from java run-time it does not. Any suggestions or advice?

Answer 1

Use the newer ProcessBuilder class instead of Runtime.exec. You can construct one by specifying the program and its list of arguments as shown in my code below. You don’t need to use single-quotes around the command. You should also read the stdout and stderr streams and waitFor for the process to finish.

ProcessBuilder pb = new ProcessBuilder("ssh", 
                                       "user@127.0.0.1", 
                                       "export MYVAR=this/dir/is/cool; /run/my/script/myScript; echo $MYVAR");
pb.redirectErrorStream(); //redirect stderr to stdout
Process process = pb.start();
InputStream inputStream = process.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String line = null;
while((line = reader.readLine())!= null) {
    System.out.println(line);
}
process.waitFor();