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I need to execute this script from my Python script.

Is it possible? The script generate some outputs with some files being written. How do I access these files? I have tried with subprocess call function but without success.

fx@fx-ubuntu:~/Documents/projects/foo$ bin/bar -c somefile.xml -d text.txt -r aString -f anotherString >output

The application "bar" also references to some libraries, it also create the file "bar.xml" besides the output. How do I get access to these files? Just by using open()?

Thank you,

Edit:

The error from Python runtime is only this line. 

$ python foo.py
bin/bar: bin/bar: cannot execute binary file
fx.
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    subprocess is what you need to use, can you provide an example so we have a better idea why it didn't work? – Kaleb Pederson Mar 18 '10 at 22:08
  • "subprocess call"? What is that? Please post the code you used and the error you actually got. – S.Lott Mar 18 '10 at 22:51
  • Yes, he's talking about the "call" function in the standard "subprocess" module, which is the better way to do this, although os.system may be adequate depending on his needs – Peter Lyons Mar 19 '10 at 01:37
  • Hi Kaleb, I edited the question. – fx. Mar 19 '10 at 12:04

3 Answers3

46

For executing the external program, do this:

import subprocess
args = ("bin/bar", "-c", "somefile.xml", "-d", "text.txt", "-r", "aString", "-f", "anotherString")
#Or just:
#args = "bin/bar -c somefile.xml -d text.txt -r aString -f anotherString".split()
popen = subprocess.Popen(args, stdout=subprocess.PIPE)
popen.wait()
output = popen.stdout.read()
print output

And yes, assuming your bin/bar program wrote some other assorted files to disk, you can open them as normal with open("path/to/output/file.txt"). Note that you don't need to rely on a subshell to redirect the output to a file on disk named "output" if you don't want to. I'm showing here how to directly read the output into your python program without going to disk in between.

Peter Lyons
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  • Hi Peter, there is the error: bin/bar: bin/bar: cannot execute binary file and without any other information from the Python runtime. What is the cause? – fx. Mar 19 '10 at 11:51
  • it's about the executable's error. I have solved it, thanks Peter. – fx. Mar 20 '10 at 17:29
20

The simplest way is:

import os
cmd = 'bin/bar --option --otheroption'
os.system(cmd) # returns the exit status

You access the files in the usual way, by using open().

If you need to do more complicated subprocess management then the subprocess module is the way to go.

rz.
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    Note that this has the same security caveat as `subprocess.Popen(shell=True)`. Don't use it with anything other than a literal string. – Brian McCutchon May 01 '19 at 01:04
  • I want to execute `tesseract` on every file in my folder, so I os.walk and then do the progr in the loop. How does it work? – Timo Nov 11 '20 at 18:52
9

For executing a unix executable file. I did the following in my Mac OSX and it worked for me:

import os
cmd = './darknet-classifier-predict-data/baby.jpg'
so = os.popen(cmd).read()
print(so)

Here print(so) outputs the result.

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Sumesh Chandran
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