Earlier I posted a question regarding this issue. I managed to go a step further. Anyway, this is another similar question

Write a programme that creates a ring of three processes connected by pipes. The first process should prompt the user for a string and then send it to the second process . The second process should reverse the string and send it to the third process. The third process should convert the string to uppercase and send it back to the first process. When the first process gets the resultant string, it should display it to the terminal. When this is done, all three processes should terminate

I managed to write from A->b->c, but I do not know how to join from C -> A.
mY lecturer asked me to create another pipe in advance before A starts fork(), and I did so, but although I pass in the message I do not get any result. On top of that, the B->C is also affected, it is not showing any result anymore.

Anyone able to help on this?
Greatly appreciate it.

so far from what I have understood what you are asking is pretty basic but there is no given example of the work that you have done already and the siubject that you are talking about sounds is pretty broad..
this i would say try a loop... say! a for or while loop and nest an if statment to guarantee that the commands you want to execute get executed...
ex.,
while (expression)
do (-------------------------->a
if (expression)
then......................................>b
(command)
else..........................................>c
(command)
fi
done (loop) use break coomand to terminte loop at specific point
if expression a is a always true c will go back to a
moxxx68

__________________
moxxx68
http://www.estarinformado.com.ar/apicmaxmiel/bee-diez.gif

Post what you have, lets see what you have done. Are you writing a C program or are you attempting to do this in shell using co-processes or signals.