java 调用linux 下的程序不成功

代码如下
[code="java"]

Runtime run = Runtime.getRuntime();

    Process prs = run.exec("echo 'hello' >/root/123.txt");
    OutputStream out = prs.getOutputStream();
    InputStream in = prs.getInputStream();
    InputStream err = prs.getErrorStream();
    byte[] er = new byte[1024];

    byte[] b = new byte[1024] ;
    //in.read(b);
    while(in.read(b)>0){
        System.out.println(new String(b));
    }

        System.out.println(prs.waitFor());

[/code]
waitFor 返回为0表示成功可是我在/root/下找补到123.txt
希望大家给予帮助谢谢

参照：
proc = Runtime.getRuntime().exec(new String[] {"/bin/sh","-c", comand});