piping with subprocess
Rick Dooling
rpdooling at gmail.com
Sat Feb 1 10:35:01 EST 2014
On Saturday, February 1, 2014 8:00:59 AM UTC-6, Rick Dooling wrote:
> On Saturday, February 1, 2014 7:54:34 AM UTC-6, Rick Dooling wrote:
>
> > On Saturday, February 1, 2014 6:54:09 AM UTC-6, Peter Otten wrote:
>
> > > Rick Dooling wrote:
>
> > > > I spent half a day trying to convert this bash script (on Mac)
> > > > textutil -convert html $1 -stdout | pandoc -f html -t markdown -o $2
> > > > into Python using subprocess pipes.
>
> > > > It works if I save the above into a shell script called convert.sh and
> > > > then do
> >
> > > > subprocess.check_call(["convert.sh", file, markdown_file])
>
> > > > where file and markdown_file are variables.
>
> > > > But otherwise my piping attempts fail.
>
> > > It is always a good idea to post your "best effort" failed attempt, if only to give us an idea of your level of expertise.
> > > > Could someone show me how to pipe in subprocess. Yes, I've read the doc,
> > > > especially http://docs.python.org/2/library/subprocess.html#replacing-shell-pipeline
>
> > > > But I'm a feeble hobbyist, not a computer scientist.
>
> > > 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.
> > Thanks,
> > RD
> > ps - Daniel's works fine but I still don't learn to pipe :)
> Okay, sorry. I fixed that obvious goof
> p1 = subprocess.Popen(["textutil", "-convert", "html", file], stdout=subprocess.PIPE)
>
> p2 = subprocess.Popen(["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]
>
> Now I get no errors, but I still get a blank markdown file.
Okay, blank lines removed. Apologies. I didn't know Google inserted them.
RD
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