How to run a CLI command from a Python script?

Question

When I write this in CMD (Windows 10) it's OK. The recognized text is in the clipboard: "C: \ Program Files (x86) \ ABBYY FineReader 15 \ FineReaderOcr.exe" "C: \ Python39 \ Scripts \ abbyy \ Skan.JPG" / send Clipboard

I would like to do the same with a Python script to be able to parse the contents of the clipboard. I am trying to do this using:

import sys
import os
def mycmd():
  os.system('cmd /c "C:\Program Files (x86)"\ABBYY FineReader 15\FineReaderOcr.exe" "skan.JPG" " /send Clipboard"')
mycmd()

But it doesn't work and you get the following error: 'C: \ Program' is not recognized as an internal or external command, operable program or batch file.

I also tried using subprocess: import of os

import subprocess
program = 'C: \ Program Files (x86) \ ABBYY FineReader 15 \ FineReaderOcr.exe'
file = 'C: \ Python39 \ Scripts \ abbyy \ Skan.JPG'
lang = "/ lang Polish"
send = "/ send Clipboard"
subprocess.run (["C: \ Program Files (x86) \ ABBYY FineReader 15 \ FineReaderOcr.exe", "scan.JPG", "/ send Clipboard"])
subprocess.call ([program, file, send])

But it also doesn't work as it should. Please tell me why it doesn't work and how to do it correctly?

regards

Use subprocess. This replaces os.system and os.spawn*. docs.python.org/3/library/subprocess.html — lit
– lit, Commented Nov 17, 2021 at 14:38

rkechols · Accepted Answer · 2021-11-17 10:19:47Z

5

Whitespace is important.

The space within Program Files is making that first file path be interpreted as two separate arguments, and it doesn't know how to interpret the first one, C:\Program as a command.

I've made a few similar examples to illustrate what works and what doesn't:

File paths that use no spaces

>>> import os
>>> os.system('C:\ProgramData\Miniconda3\python.exe --version')
Python 3.9.1
0
>>> os.system('cmd /c "C:\ProgramData\Miniconda3\python.exe --version"')
Python 3.9.1
0
>>> os.system(r'cmd /c "C:\ProgramData\Miniconda3\python.exe --version"')
Python 3.9.1
0

These 3 versions are all successful because C:\ProgramData\Miniconda3\python.exe, the file path in question, has no spaces in it.

File paths with spaces and \u

This command doesn't work:

>>> os.system('C:\Program Files (x86)\LilyPond\usr\bin\python.exe --version')
  File "<stdin>", line 1
    os.system('C:\Program Files (x86)\LilyPond\usr\bin\python.exe --version')
                                                                            ^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 31-32: truncated \uXXXX escape

because it contains \u (in ...\usr\...). When you use \u as part of a string, python expects it to be a part of a Unicode escape sequence (e.g. print("\u2019") will get you a special apostrophe)

The way to fix this is to either escape your backslashes with another backslash (e.g. 'C:\\ProgramData\\...') or by making it a "raw" string with a prefixed r: r'C:\ProgramData\...'

That gets us here:

>>> os.system(r'C:\Program Files (x86)\LilyPond\usr\bin\python.exe --version')
'C:\Program' is not recognized as an internal or external command,
operable program or batch file.
1

which is the problem I initially described; spaces are used to break up commands/arguments and cannot plainly be included in file paths.

The solution is to put quotes around the whole file path which contains a space:

>>> os.system(r'"C:\Program Files (x86)\LilyPond\usr\bin\python.exe" --version')
Python 3.7.4
0

These same things apply when the command is being sent as an argument:

>>> os.system(r'cmd /c "C:\Program Files (x86)\LilyPond\usr\bin\python.exe --version"')
'C:\Program' is not recognized as an internal or external command,
operable program or batch file.
1
>>> os.system(r'cmd /c ""C:\Program Files (x86)\LilyPond\usr\bin\python.exe" --version"')
Python 3.7.4
0

Conclusion

So it seems that your line should look something like this:

os.system(r'cmd /c ""C:\Program Files (x86)\ABBYY FineReader 15\FineReaderOcr.exe" skan.JPG" /send Clipboard')

(though I don't know what the /send Clipboard part is for, and so may need adjustment from this. However, this should address the error asked about in the question)

answered Nov 17, 2021 at 10:19

rkechols

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3 Comments

HajpaHajpa Over a year ago

Thanks for the extensive explanation. The last command works exactly as I expected, i.e. it runs ocr on the image and copies the result to the clipboard. Why is this code not working? (CLI) set image = scan.jpg cmd / c "" C: \ Program Files (x86) \ ABBYY FineReader 15 \ FineReaderOcr.exe ""% file% / send Clipboard Is it possible to substitute the variable 'image' here instead of the name 'scan.jpg'? How to use os.system and subprocess in this example? regards

rkechols Over a year ago

Check out tutorials for formatting strings in python: geeksforgeeks.org/string-formatting-in-python

rkechols Over a year ago

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