| Re: [ptp-user] Reading user input |
| Hi Natalie, Correct me if I'm wrong, but I suspect that it is working using mpirun because all your processes are running on the local machine. The problem is that in a cluster environment there is no guarantee that the rank 0 process will be on the same machine as the mpirun command. If the process is remote, then somehow the mpirun command needs to forward I/O between the process and your local terminal. I believe this has not been implemented for standard input in OpenMPI. If the rank 0 process is running on the local machine then it is reading directly from your terminal, which is why it works in this case. OpenMPI does forward standard out, so you will see output regardless of whether the program is running locally or remotely. Let me know if this helps, Greg On Mar 31, 2007, at 7:59 PM, Natalie Freed wrote: Thanks for answering. :) Yes, it works under OpenMPI using mpirun. I ended up using command line arguments instead, but I'm still wondering why the other way isn't possible. Unless I don't understand what input redirection is, that wasn't what I was looking for. I just want to be able to use, say, the scanf function. When I run an MPI job from the command line, I see all the output from my program from any task as the program runs. If I ask the node with rank 0 to prompt for and then read user input, the program stops and waits for me to enter a character. I'm sorry if I misunderstood your explanation or failed to explain this properly, but I'm still puzzled. |