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This is a follow up question from here specifically concerning its answer . From a python module I am calling a Hello World executable that simply prints Hello World to the stdout. I am interested in redirecting that output to a python StringIO and ran into this answer which almost brings me all the way to the solution. The critical part of this answer is this code segment: 1. def redirect_stdout(): 2. print "Redirecting stdout" 3. sys.stdout.flush() # <--- important when redirecting to files 4. newstdout = os.dup(1) 5. devnull = os.open('/dev/null', os.O_WRONLY) 6. os.dup2(devnull, 1) 7. os.close(devnull) 8. sys.stdout = os.fdopen(newstdout, 'w') Also I would like to restore the stdout as it was before the redirection. Questions What exactly is going on in the function above? What is dup and dup2 doing? What is /dev/null ? What is line 8 doing? ( sys.stdout = os.fdopen(newstdout, 'w') ) How can I store the stdout in a StringIO object? How can I restore the stdout after the call to my Hello World program? I am pretty sure that once I have the answer for my question 1 that the answers of questions 2 and 3 will be easy. I decided to post them anyway to maybe push the answer of question 1 into the direction where I want to go.

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