thanks for your reply. yes, i ran the same script on Linux, it works fine, it can connect to the remote host and execute all the commands i sent. but on Windows, it can't. The target host is a Linux machine.
I have SSH, putty and SecureCRT on my Windows, they all work fine.
yes, it can login, but when executing the comand, it hangs. very strange, if i change the command as this: $ssh->cmd("ls -al > /dev/null","\n"), then it works. but i can not do that, i want the output of the command.