The read mode limits you to opening the file and reading what’s inside without being able to change or add to it. Write mode creates a file. Reading the file once it’s opened is done using the read() ...

That function ... file never grows, even though it should be filling with zeroes....<BR><BR>Does anyone know a way around this?<BR><BR>P.S. I [think I] need to interact on the os.open()/os.write ...

The problem I've noticed is that if I append the file with each of the 100k runs (one at a time), it can happen that two threads try to save to the file at the same time and some row(s) end up empty.