python使用optparse模块实现wc命令（二）

这是继上一篇的wc命令升级版，使用了optparse模块，可以带参数-l，-w，-c，下面是wc命令实现的效果：

[root@js python]# wc /etc/passwd
  32   52 1530 /etc/passwd
[root@js python]# wc -l /etc/passwd
32 /etc/passwd
[root@js python]# wc -w /etc/passwd
52 /etc/passwd
[root@js python]# wc -c /etc/passwd
1530 /etc/passwd

下面是用python编写的程序：

[root@js python]# cat parse4.py
#!/usr/bin/python
import sys
import os
from optparse import OptionParser
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")
    options,args = parser.parse_args()
    return options,args

def get_count(data):
    chars = len(data)
    words = len(data.split())
    lines = data.count('\n')
    return lines,words,chars

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\n" %fn
            else:
                sys.stderr.write("wc: %s No such file or directory\n" %fn)
        if len(args) > 1:
            print_wc(options,total_lines,total_words,total_chars,'total')
    else:
        data = sys.stdin.read()
        fn = ''
        lines,words,chars = get_count(data)
        print_wc(options,lines,words,chars,fn)

main()

简单测试一下：

[root@js python]# python parse4.py /etc/passwd
32 52 1530 /etc/passwd
[root@js python]# python parse4.py -l /etc/passwd  
32 /etc/passwd
[root@js python]# python parse4.py -wcl /etc/passwd
32 52 1530 /etc/passwd
[root@js python]# python parse4.py -wcl /etc/passwd /etc/hosts
32 52 1530 /etc/passwd
2 10 158 /etc/hosts
34 62 1688 total
[root@js python]# python parse4.py  /etc/passwd /etc/hosts
32 52 1530 /etc/passwd
2 10 158 /etc/hosts
34 62 1688 total
[root@js python]# cat /etc/passwd |python parse4.py 
32 52 1530

基本实现了wc的功能，结束。