Why is Runtime.Exec not perfekct?

Question

Hi!
I need to execute a program from java using Runtime.Exec(). I have done everything right with redirection the output stream and read it from a seperate thread. This works for most of the programs I tried, but not for all. Sometimes I miss some of the output.
But if I use redirection to a file from the shell it works perfect.
(i.e. /bin/pramsim > outfil)
Why is this? Why isn't Runtime.exec as good as shell redirection?
/Karl

Answer 1

Ok sorry, here is some more detalis.
The program( pramsim) prints to both standard output and standard error. Output written to stderr does always work. But output so stout fails quite often. After some research I found out that pramsim is using the function printf(...) which is bufferd by default. So I only get the output when the program prints alot, so the buffer gets full.
Can I in some way turn buffering off from java? Found a C function called setbuf(1,null) which turns buffering off. But this means I have to changes the code to pramsim, and I want to avoid that!
I also wonder: How does redirection in the shell make this work. I guess buffering is turned off when I redirect to a file using 'pramsim > outfil'. (maybe this is more a C question but I hope that I can get some help here)
/Karl