Running batch command in Python script

Question

I am trying to execute a batch command in a Python script, simply showing the PDFs file name. Basically, the Python script is in a folder C:\users\me\desktop\python which should execute a command on a different folder on the desktop (C:\users\me\desktop\some-folder), which has subfolders with PDFs in it.

Here is the code:

from subprocess import call
import os

for root, dirs, files in os.walk("../some-folder"):
    for pdf_file in files:
        if pdf_file.endswith(".pdf"):
            pdf_file_path = os.path.join(root, pdf_file)
            os.chdir(root)
            call('for %%f in (*.pdf) do @echo %%f')

The result I get is "file not found".

If you are already getting the pdf names with python why are you trying to iterate them again with a cmd.exe FOR command? I don't see how this is a batch file problem. You really have no batch-file code in this question. — Squashman
– Squashman, Commented Feb 17, 2017 at 13:19

Jean-François Fabre · Accepted Answer · 2017-02-17 18:47:17Z

3

First, since you're activating built-in DOS commands, you'd have to set shell=True to run such commands.

Second, even with that it won't work, since double percent are reserved for scripts. In-line command require one sole %.

And third: don't use os.chdir, it's bad practice. Better use cwd option of subprocess calls, allows to locally change the directory when running the command.

That would work:

call('for %f in (*.pdf) do @echo %f',shell=True,cwd=root)

Of course this is probably an example since your command accomplishes nothing: you don't get the output back in your python script, you don't check return code...

If you want to get the list of *.pdf in python in root directory (with full path), I guess that you know

list_of_pdfs = glob.glob(os.path.join(root,"*.pdf"))

or in relative:

list_of_pdfs = [x for x os.listdir(root) if fnmatch.fnmatch(x,"*.pdf")]

but since you're in an os.walk loop, you'll get the output as many times as there are .pdf files, so it's not very performant / bad design & complexity.

For your whole conversion loop I would call the converter for each file, no need for .bat scripting, you have python!:

from subprocess import call
import os

for root, dirs, files in os.walk("../some-folder"):
    for pdf_file in files:
        if pdf_file.endswith(".pdf"):
           call([r"C:\xpdf\bin32\pdftotext","-raw",pdf_file], cwd=root)

passing arguments in a list automatically handles spaces in filenames.

edited Feb 17, 2017 at 18:47

answered Feb 17, 2017 at 11:46

Jean-François Fabre♦

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9 Comments

vdvaxel Over a year ago

Thanks, this worked! However, when I just print the PDF file names like in the example, all PDFs appear multiple times even though they're only in the list once?

vdvaxel Over a year ago

I see that you edited your answer: I indeed get the output as many times as there are .pdf files. How should I change my code to prevent this?

Jean-François Fabre Over a year ago

Do you want to just print the files or do something else?

vdvaxel Over a year ago

No that was indeed just an example, I actually want to convert the PDFs to TXT. But if every file is being converted 100 times, it will be very slow. So only the 'call' command is different: call('for %f in (*.pdf) do "C:\\xpdf\\bin32\\pdftotext" -raw "%f"', shell=True, cwd=root)

vdvaxel Over a year ago

Since the Python loop loops over all files, is it possible to just execute the 'call' command for that specific file instead of the entire map? I guess that would solve it.

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