You have to append "\n" to your command strings. You will also have to account for the shell prompt lines.

If I recall correctly, IPC::Open2 already sets the file handles in autoflush mode. Otherwise, you will have to do it yourself.

In any case, installing OpenSSH on Solaris is quite easy, precompiled packages are available from SUN freeware, and they only have a few dependencies. Talking to the shell is a flawed approach that would break when you least expect it.