Short version: Try adding a "sys.stdout.flush()" after each of your print 
statements in your python script.

Longer version: when you run that program in a terminal, the output is a 
TTY and the standard output is flushed after every line.  When you run it 
as a subprocess, the standard output is a pipe and it is buffered.

This is not Racket specific, you would get the same problem if you ran 
"os.system("test.py")" in another python program.

Alex.

On Wednesday, May 20, 2020 at 4:15:02 PM UTC+8, Rock Nie wrote:
>
> This only happens in DrRacket.
>
> On Wednesday, May 20, 2020 at 1:16:44 PM UTC+8, Rock Nie wrote:
>>
>> I am running the system procedure in drracket's interactive window
>> (system "test.py")
>>
>> where test.py is
>> #!/home/utils/Python-3.8.0/bin/python3
>> import os
>>
>> print("Running cmd: date1")
>> print("Running cmd: date2")
>> os.system("date")
>> print("Running cmd: date3")
>> os.system("date")
>>
>> and the output is
>> Tue May 19 22:14:19 PDT 2020
>> Tue May 19 22:14:19 PDT 2020
>> Running cmd: date1
>> Running cmd: date2
>> Running cmd: date3
>> #t
>>
>> which is different from my expectation, can anyone help explain why?
>>
>>

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