title: curl: when is output file created
body: <p>In case one has requested that the curl output be transferred to output.txt, then when exactly is the output file created. </p>
  
  <p>I ask this because of the following issue that I am facing:
  1. I give an rpc call which has a lot of data to be retrieved. 
  2, After the date is retrieved, i then go and read output.txt to get all the data i need.
  3. But some rpc calls take some time for the data to be retrieved (as lot of data), thus I am not sure how long to wait before i go to read output.txt
  4. I don't wish to give any random number as it would slow down the code.
  5. Now i was thinking if output file is created after all the data is received then it woudl be easy as i just need to check for the existence of output.txt and then go an read. 
  But i am not sure if this is what happens thus i ask this question?</p>
  
  <p>could someone please help me with this issue?
  thanks
  sunny</p>