4

I want to count how many lines of code I have written.

Here is the Python code:

import os
import sys

EXT = ['.c','.cpp','.java','.py']

def main():
    l = []
    if os.path.isdir(sys.argv[1]):
        for root, dirs, files in os.walk(sys.argv[1]):
            l.extend([os.path.join(root, name) for name in files])
    else:
        l.append(sys.argv[1])

    params = ["'"+p+"'" for p in l if os.path.splitext(p)[1] in EXT]

    result = os.popen("wc -l %s "%" ".join(params)).read()
    print result

if __name__ == '__main__':
    main()

Before this, it was running as expected. But today, it give me this error:

sh: 1: Syntax error: Unterminated quoted string

I don't know what happened.

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4
  • 2
    How are you executing this script? Commented Aug 31, 2013 at 3:17
  • @Johnsyweb python program.py . Commented Aug 31, 2013 at 3:42
  • 1
    Try adding print params before your popen line. Do any of the elements in params have a single quote in them? Commented Aug 31, 2013 at 5:09
  • 2
    you should also consider using the newer subprocess module instead of popen Commented Aug 31, 2013 at 5:52

3 Answers 3

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5

Your Python script is missing a shebang line. Add the following to the top of your file:

#!/usr/bin/env python

Then you should be able to run the following, assuming your script is at /path/to/your_script.py and it has the executable bit set:

/path/to/your_script.py arg1 arg2 [...]

Alternatively:

python /path/to/your_script.py arg1 arg2 [...]

Update following comments

I suspect what has changed is that a source file containing a ' in its name has been added to the directory you are checking and the shell is choking on this.

You could add the following function to your program:

def shellquote(s):
    return "'" + s.replace("'", "'\\''") + "'"

[Lifted from Greg Hewgill's answer to How to escape os.system() calls in Python? .]

And call it like this:

params = [shellquote(p) for p in l if os.path.splitext(p)[1] in EXT]
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5 Comments

@maemual: The same "wrong" or a different "wrong"? What is the output of which python (and python --version)?
which python /usr/bin/python, python --version 2.7.3
To be clear, the first line is to be added to the top of the script itself; the second and third are commands to be executed from the shell. And see this question and my answer for discussion of the #!/usr/bin/env trick; the alternative is #!/usr/bin/python
@maemual: Then I have a new theory and have updated my answer.
Yes, it's the true problem.THX!
1

@Johnsyweb's updated answer seems to have the correct diagnostic, but the correct fix is to not use a shell to invoke wc. Try something like this instead:

cmd = ['/bin/wc', '-l'] # Need full path!
[cmd.extend(p) for p in l if os.path.splitext(p)[1] in EXT]
result = os.popen2(cmd).read()

Note that the subprocess module is the recommended solution now. Switching to that requires a less intrusive change to your current code, though; see http://docs.python.org/2/library/subprocess.html#replacing-os-popen-os-popen2-os-popen3

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2 Comments

Nice fix, but why are you creating a list comprehension here?
@Johnsyweb: Lazy copy/paste; not at my computer so didn't want to change more than absolutely necessary. Feel free to edit, or adopt into your answer.
0

Looks like your Python program was parsed like a shell script. Add something like this at the header to indicate where your Python is:

#!/usr/bin/python

or you just run python a.py.

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