Example code for using python to implement the functions of wc command program

The basic code of python is used here to implement the basic functions of the wc command program under the Linux system.

#!/usr/bin/env python
#encoding: utf-8
# Author: liwei
# Function: wc program by python
 
from optparse import OptionParser
import sys,os
 
def opt():
    parser = OptionParser()
    parser.add_option('-c', '--char',
                      dest='chars',
                      action='store_true',
                      default=False,
                      help='only count chars')
 
    parser.add_option('-w', '--word',
                      dest='words',
                      action='store_true',
                      default=False,
                      help='only count words')
 
    parser.add_option('-l', '--line',
                      dest='lines',
                      action='store_true',
                      default=False,
                      help='only count lines')
     
    parser.add_option('-n', '--nototal',
                      dest='nototal',
                      action='store_true',
                      default=False,
                      help='don\'t print total information')
 
    options, args = parser.parse_args()
    return options, args
 
#print options
def get_count(data):
    chars = len(data)
    words = len(data.split())
    lines = data.count('\n')
    return lines, words, chars
 
#if not options.chars and not options.words and not options
 
def print_wc(options, lines, words, chars, fn):
    if options.lines:
        print lines,
    if options.words:
        print words,
    if options.chars:
        print chars,
    print fn
 
def main():
    options, args = opt()
     
    if not (options.lines or options.words or options.chars):
        options.lines, options.words, options.chars = True, True, True
     
     
    if args:
        total_lines, total_words, total_chars = 0, 0, 0
        for fn in args:
            if os.path.isfile(fn):
                with open(fn) as fd:
                    data = fd.read()
                lines, words, chars = get_count(data)
                print_wc(options, lines, words, chars, fn)
                total_lines += lines
                total_words += words
                total_chars += chars
            elif os.path.isdir(fn):
                print >> sys.stderr, '%s is a directory' %fn
            else:
                sys.stderr.write('%s: No such file or directory\n' % fn)
        # 只有多个文件的时候会计算出total字段
        if len(args) > 1 and not options.nototal:
            print_wc(options, total_lines, total_words, total_chars, 'total')
    else:
        fn = ''
        data = sys.stdin.read()
        lines, words, chars = get_count(data)
        print_wc(options, lines, words, chars, fn)
     
if __name__ == '__main__':
    main()

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