Exemple de code pour utiliser Python pour implémenter les fonctions du programme de commande wc

Le code de base de python est utilisé ici pour implémenter les fonctions de base du programme de commande wc sous le système Linux.

#!/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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