How to read JSch command output?

问题:

I have the following code:

JSch jsch = new JSch(); jsch.setKnownHosts(dotSshDir + "/known_hosts"); jsch.addIdentity(dotSshDir + "/id_rsa");  Session session = jsch.getSession(userName, hostname, 22); session.connect();  ChannelExec channel = (ChannelExec) session.openChannel("exec"); channel.setCommand(command); channel.setInputStream(null); channel.setErrStream(System.err); Reader reader = new InputStreamReader(channel.getInputStream());  char[] buf = new char[1024]; int numRead; while ((numRead = reader.read(buf)) != -1) {     String readData = String.valueOf(buf, 0, numRead);     result.append(readData);     buf = new char[1024]; }

It's hanging trying to read from the reader. How do I fix this? How do I go about hunting down what's happening?

回答1:

The hanging was actually due to some unbalanced quotes in the command.

For posterity, the final code (after dealing with some other issues) is:

public String call(String hostname, String[] argv) throws SubprocessException {     StringBuffer result = new StringBuffer();      Session session = null;     ChannelExec channel = null;      try {         // TODO: Emit friendly error if ~/.ssh doesn't exist.         String dotSshDir = System.getProperty("user.home") + "/.ssh";         String userName = System.getProperty("user.name");          // TODO: Emit friendly error if ~/.ssh/known_hosts doesn't exist.         jSch.setKnownHosts(dotSshDir + "/known_hosts");         // TODO: Emit friendly error if ~/.ssh/id_rsa doesn't exist.         jSch.addIdentity(dotSshDir + "/id_rsa");          session = jSch.getSession(userName, hostname, 22);         session.connect();          channel = (ChannelExec) session.openChannel("exec");         channel.setCommand(Joiner.on(" ").join(argv));         channel.setInputStream(null);         InputStream stdout = channel.getInputStream();         InputStream stderr = channel.getErrStream();         channel.connect();          waitForChannelClosed(channel);          if (channel.getExitStatus() != 0) {             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stderr));             readAll(bufferedReader, result);              throw new Exception(result.toString());         } else {             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(stdout));             readAll(bufferedReader, result);         }     } catch (Exception e) {         throw new SubprocessException(e);     } finally