How to replace rexec by using ssh?

Hi, everybody:

I got a problem when I try to use ssh instead of using rexec() function
in my code.

Previously, my code contains fd=rexec(&hostname,port, ....) to remotely
start the program in other machines. However, rexec is not allowed in
the new cluster (it seems all the linux clusters do not allow
r..command now). I have to use ssh instead.

Since I need to use the information of fd for the following
communication. But ssh does not return such information. So I fork the
processes as:
First, a socket is created

Then, the child process keep listening. The father process use
system("ssh....") to remote start that node.

It does not work well. The error shows that these two machine do not
communicate in a nice way.
Is there any wrong with my idea? I cann't find the source code of rexec
and don't know their work principle. What is the exactly difference
between rexec and ssh(ignoring their security mechanism)? Great thanks

Xumin

On Fri, 02 Jun 2006 16:33:46 -0700, Xumin.Lucky wrote:

> Then, the child process keep listening. The father process use
> system("ssh....") to remote start that node.

First, you should look for a library in your chosen language (C?) which
would do what you need. I recently came across one for Perl (no, it
doesn't fork() off processes), as it happens. There may very well be one
for your language too.

What about: http://netsieben.com/products/sshlib/specs.phtml

Or: http://freshmeat.net/projects/libssh/

Alternatively, if I were doing what you appear to be doing I'd have the
child process providing the SSH behavior. Since you can have the
information flowing whichever way you want, I don't suppose this is too
important. But I think it would mean less change for your code. The
child process, and a couple of pipe()s, provides you with descriptors into
and out from the SSH process that your parent process can use similarly
the descriptors from the rexec() call.

It should be workable.

You wrote:

> The error shows that these two machine do not
> communicate in a nice way.

but don't explain what you mean by that.

- Andrew