Does System command pipe VI bufferizes data?

Question

Hi,
I have some questions about Pipe VIs on Linux:
1)In my project I open a system command pipe vi that opens another
program's shell. Then, using the write file descriptor, I write a
series of commands in a loop. I could observe that only when I close
the pipe those commands are really sent to the shell, OR when,
aparently, something like a  "pipe vi buffer" overflows.
2) In the same situation, I would like to use both the write and read
file descriptors. The write pipe vi sends a command to the program's
shell and them the read pipe vi reads the shell's results. I tried of
many ways, including forcing serialization (open, then write, then
read), but it didn't work at all. I could see that the write worked but
the read can't read the results.
The most interesting is if I use a ls -l in the open system vi, I can read the directory contents on the read vi...
What's wrong? Is that a problem of LV or Linux? Or of the another program's shell?
What can I do to make sure that a command is issued as it is writen to the pipe?
Thanks in advance for the attention,

Answer 1

Hi, ratem.
I've just created a little code snippet (below), and I'd like you to tell me what happens when you run similar code on your machine. I run the code, read from the FIFO in a terminal, and I'm able to see the data I wrote before the pipe is closed. Does your behavior differ with this code?
Message Edited by sarahk on 04-09-2006 12:36 PM
Message Edited by sarahk on 04-09-2006 12:36 PM
Sarah K.
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