[Tutor] Tutor Digest, Vol 152, Issue 3

[anish singh]

> On 01/10/16 09:16, anish singh wrote:
> > I am trying to implement grep to just increase my knowledge
> > about regular expression.
> >
> > Below is the program usage:
> > python test.py -i Documents/linux/linux/ -s '\w+_readalarm*'
> >
> > However, due to my lack of knowledge about string handling
> > in python, I am getting wrong results.
>
> Possibly, but we can't tell because
> a) You don't show us the code that parses your input
>


import os, sys, getopt

import re

import glob


def get_full_path(path, pattern):

  for (dirpath, dirnames, filenames) in os.walk(path):

    match = re.search(pattern, dirpath)

    for filename in filenames:

      if filename.endswith(('.c', '.h')):

        yield os.path.join(dirpath, filename)


def read_file(file, pattern):

  with open(file, 'r') as infile:

    for line in infile:

      match = re.compile(str(pattern)).match(line)

      if match:

        print(file + " " + match.group())



def main(argv):

  path, f_pattern, s_pattern = '', '', ''

  try:

    opts, args =
getopt.getopt(argv,"hi:p:f:s:",["ifile=","file_pattern=","string_pattern="])

  except getopt.GetoptError:

    print 'test.py -i <path> -p <pattern>'

    sys.exit(2)

  for opt, arg in opts:

    if opt == '-h':

       print 'test.py -i <path>'

       sys.exit()

    elif opt in ("-i", "--ifile"):

      path = arg

    elif opt in ("-f", "--file_pattern"):

      f_pattern = arg

    elif opt in ("-s", "--string_pattern"):

      s_pattern = arg.encode().decode('unicode_escape')

      print(s_pattern)


    files = get_full_path(path, f_pattern)

    for file in files:

      read_file(file, s_pattern)


if __name__ == "__main__":

  main(sys.argv[1:])


> b) You don't show us your output/error message
>

output is only file names. I don't see any other output.
I am running it like this:
python test.py -i ~/Documents/linux-next/ -s '\w*_read_register\w*'


>
> How are you parsing the input? Are you using
> the argparse module? Or one of the older ones?
> Or are you trying to just test the values in sys.argv?
>

You can see the code now.


>
> How do you determine the input filename and the pattern?
>

Yes. Those are correct that is why i am getting all the file names.
You can run this code on any directory and see it just provides
the output as file names.

> Have you proved that those values are correct before you
> call your read_file() function?
>

Yes.

>
>
> > def read_file(file, pattern):
> >    with open(file, 'r') as outfile:
>
> Since you are reading it it probably should be
> called infile?
>

Done.

>
> >      for line in outfile:
> >        match = re.compile(str(pattern)).match(line)
> >        if match:
> >          print(file + " " + match.group())
>
>
> > Can someone let me know how can I pass regular expression
> > from command line?
>
> The real issue here is probably how you parse the
> input line but we can't tell. The recommended module
> for doing that is argparse. Try reading the module
> documentation which includes many examples.
>
> If you are still having problems show us your full
> program plus any error messages
>
> > Whole code: http://ideone.com/KxLJP2
>
> Unless its very long (>100lines?) just post it
> in your email.
>
>
>