[Tutor] os.system sending of break signals

Johan Geldenhuys johan at accesstel.co.za
Fri Oct 28 10:21:46 CEST 2005

If I use popen2, I need to write to one of the tuple parts.
 >>> f = os.popen2('ping -c 100 > cap1.txt')
 >>> f[0].write('\x03')

Thank command works, but 'f[1]' is in read-only mode and I can't write 
to it.
My command in the background is still not terminated.

BTW I use Linux as OS.

So, it doesn't work.

Alan Gauld wrote:

>> >>> f = os.popen('ping -c 100 > cap2.txt')
>> You will see that I send the output from the command to a file, 
>> because I want to test how stop the command before it reaches 100 pings.
>> If I don't write the output to the file 'cap2.txt' and succeeds in 
>> closing 'f', all the data returned to 'f' will be lost.
> You can read the output of popen into your program with
> f.read(), but that will read all of the output after the program has 
> run. However I think you can readline() too to catch it line by line. 
> You can also write() data to f thus allowing you to send your 
> Ctrl-C.(You may need popen2 or even popen3 to do the simultaneous 
> read//write bit. #Or better still use the new subprocess module in v2.4)
> Does that do what you need?
> Alan G

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