You are right, java -version output to stderr. On May 5, 2010, at 3:27 AM, Heiner Westphal wrote:
> many programs on unices use stdout for data and stderr for error and > informational messages. > This way you can chain commands by piping stdout and still see warnings > which go to stderr and would otherwise get confused with incoming data. > > e.g.: > $ grep ^/dev/ /etc/mtab /etc/ntab | wc -l > grep: /etc/ntab: No such file or directory > 7 > > > wc got the data, but I still can see if s.t. went wrong > with grep. > > If version information is data or other information is just > a matter of taste. > Since java does not support the -version option while running > a class, I would have expected stdout as you did, because > there is no other data to be expected. > > Regards, > > Heiner > > Haidong Zhu wrote: >> Thanks for reply, but why the message i need comes from err stream? >> On May 4, 2010, at 11:40 AM, Keith Alan Richardson wrote: >>> You print only the stdout or stderr, depending on the exit code >>> >>> Try printing both. >>> >>> >>>> On May 4, 2010 6:27 AM, "Haidong Zhu" <[email protected] >>>> <mailto:[email protected]>> wrote: >>>> >>>> Below is my code，if i set the command as "ls ~/" I can get the output of >>>> command ls by reading the input stream from channel. >>>> >>>> if i set the command as "java -version", i can not get any output and >>>> the exitcode is 0. >>>> >>>> command = "ls ~/"; >>>> //command = "java -version"; >>>> InputStream in = null; >>>> InputStream err = null; >>>> BufferedReader inReader = null; >>>> BufferedReader errReader = null; >>>> try { >>>> JSch jsch = new JSch(); >>>> Session session = jsch.getSession(user, host, port); >>>> session.setUserInfo(userInfo); >>>> session.setTimeout(timeout); >>>> session.connect(); >>>> Channel channel = session.openChannel("exec"); >>>> ((ChannelExec)channel).setCommand(command); >>>> channel.setInputStream(null); >>>> ((ChannelExec)channel).setErrStream(null); >>>> >>>> in = channel.getInputStream(); >>>> err = ((ChannelExec)channel).getErrStream(); >>>> >>>> channel.connect(); >>>> >>>> int exitCode = 0; >>>> while(true) { >>>> if(channel.isClosed()){ >>>> exitCode = channel.getExitStatus(); >>>> break; >>>> } >>>> try { >>>> Thread.sleep(1000); >>>> } catch (InterruptedException ie) { >>>> } >>>> } >>>> >>>> inReader = new BufferedReader(new InputStreamReader(in)); >>>> errReader = new BufferedReader(new InputStreamReader(err)); >>>> >>>> if (exitCode != 0) { >>>> while ((s = errReader.readLine()) != null) { >>>> sb.append(s).append("\n"); >>>> } >>>> status.setData(sb.toString()); >>>> } else { >>>> while ((s = inReader.readLine()) != null) { >>>> sb.append(s).append("\n"); >>>> } >>>> System.out.println(sb.toString()); >>>> } >>>> >>>> ------------------------------------------------------------------------------ _______________________________________________ JSch-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/jsch-users
