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Date: Fri, 23 Dec 2011 01:18:48 +0000
From: MRAB <python@mrabarnett.plus.com>
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Subject: Re: reading multiline output
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On 23/12/2011 01:07, Mac Smith wrote:
>
> On 23-Dec-2011, at 6:17 AM, MRAB wrote:
>
>> On 23/12/2011 00:33, Mac Smith wrote:
>>> Hi,
>>>
>>>
>>> I have started HandBrakeCLI using subprocess.popen but the output
>>> is multiline and not terminated with \n so i am not able to read
>>> it using readline() while the HandBrakeCLI is running. kindly
>>> suggest some alternative. i have attached the output in a file.
>>>
>> The lines are terminated with \r, so read with read() and then
>> split on "\r".
>
> read() will read the complete output and than i will be able to parse
> it, i want to read the output of the command in realtime.
>
Try telling it how much to read with read(size):

def read_lines(output, line_ending="\n"):
     buffer = ""

     while True:
         chunk = output.read(1024)
         if not chunk:
             break

         buffer += chunk

         while True:
             pos = buffer.find(line_ending)
             if pos < 0:
                 break

             pos += len(line_ending)
             yield buffer[ : pos]
             buffer = buffer[pos : ]

     if buffer:
         yield buffer