piping with subprocess
Peter Otten
__peter__ at web.de
Sat Feb 1 12:32:14 EST 2014
Rick Dooling wrote:
> On Saturday, February 1, 2014 6:54:09 AM UTC-6, Peter Otten wrote:
>> Try to convert the example from the above page
>>
>> """
>> output=`dmesg | grep hda`
>> # becomes
>> p1 = Popen(["dmesg"], stdout=PIPE)
>> p2 = Popen(["grep", "hda"], stdin=p1.stdout, stdout=PIPE)
>> p1.stdout.close() # Allow p1 to receive a SIGPIPE if p2 exits.
>> output = p2.communicate()[0]
>> """
>>
>> to your usecase. Namely, replace
>>
>> ["dmesg"] --> ["textutil", "-convert", "html", infile, "-stdout"]
>> ["grep", "hda"] --> ["pandoc", "-f", "html", "-t", "marktown", "-o",
>> outfile]
>>
>> Don't forget to set
>>
>> infile = ...
>> outfile = ...
>>
>> to filenames (with absolute paths, to avoid one source of error).
>> If that doesn't work post the code you wrote along with the error
>> messages.
>
> p1 = subprocess.Popen(["textutil", "-convert", "html", file],
> stdout=subprocess.PIPE)
> p2 = subprocess.check_call(["pandoc", "-f",
> "html", "-t", "markdown", "-o", markdown_file], stdin=p1.stdout,
> stdout=subprocess.PIPE)
> p1.stdout.close() # Allow p1 to receive a SIGPIPE if p2 exits.
> output = p2.communicate()[0]
>
> Errors
>
> Traceback (most recent call last):
> File "/Users/me/Python/any2pandoc.py", line 70, in <module>
> convert_word_file(file, markdown_file)
> File "/Users/me/Python/any2pandoc.py", line 59, in convert_word_file
> output = p2.communicate()[0]
> AttributeError: 'int' object has no attribute 'communicate'
>
> I get a markdown_file created but it's empty.
Well, you replaced the Popen() from the example with a check_call() which
uses a Popen instance internally, but does not expose it.
I recommend that you stick as closely to the example as possible until you
have a working baseline version. I'd try
textutil = subprocess.Popen(
["textutil", "-convert", "html", file],
stdout=subprocess.PIPE)
pandoc = subprocess.Popen(
["pandoc", "-f", "html", "-t", "markdown", "-o", markdown_file],
stdin=textutil.stdout)
textutil.stdout.close()
pandoc.communicate()
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