作业：实现简单的shell sed替换功能和修改haproxy配置文件

1.实现简单的shell sed替换功能：

1 find_str='我有太多歌曲永远不会被唱起'
2 replace_str='YOUTAIDUODEGEQUYONGYUANBUHUIBEICHANGQI'
3 
4 with open('yesterday','r',encoding='utf-8') as f,
5     open('yesterday.bak','w',encoding='utf-8') as f_new:
6     for line in f:  # f为一个迭代器，按行迭代
7         if find_str in line:
8             line = line.replace(find_str, replace_str)  # 字符串替换replace函数
9         f_new.write(line)

2.修改haproxy配置文件(节点搜索、添加和删除)：

 1 while True:
 2 
 3     menu=input('''
 4 ------请选择功能------
 5 搜索节点请输入S:
 6 添加节点请输入A:
 7 删除节点请输入D:
 8 退出请输入Q：
 9 ''',)
10 
11     if menu=='S':
12         website=input('请输入网址：')
13         node='backend'+' '+website
14         with open('haproxy.txt','r',encoding='utf-8') as f:
15             count=0
16             N=-2
17             for line in f:#使用迭代占用内存小
18                 if line.strip()==node:#去掉两边空格之后判断
19                     N=count
20                 if count==N+1:
21                     print('''节点{_website}信息为:{_info}
22                     '''.format(_website=website,_info=line.strip()))
23                 count+=1
24             if N==-2:
25                 print('该节点不存在')
26             print(N)
27 
28     elif menu=='A':
29         website=input('请输入您要添加的节点网址：')
30         server=input('请输入您要添加的节点地址：')
31         weight=input('请输入您要添加的节点weight：')
32         maxconn=input('请输入您要添加的节点maxconn：')
33         backend='backend'+' '+website
34         record='        '+'server'+' '+server+' '+'weight'+' '+weight+' '+'maxconn'+' '+maxconn
35 
36         with open('haproxy.txt','a',encoding='utf-8') as f:
37             f.write('
')
38             f.write(backend)
39             f.write('
')
40             f.write(record)
41             print('添加成功')
42 
43     elif menu=='D':
44 
45         website=input('请输入您要删除的节点网址：')
46         backend='backend'+' '+website
47 
48         with open('haproxy.txt','r',encoding='utf-8') as f_read:
49             readlines = f_read.readlines()
50         with open('haproxy.txt','w',encoding='utf-8') as f_write:
51 
52             count=0
53             N=-2
54             for line in readlines:
55                 count+=1
56                 if line.strip()==backend:#删除网址
57                     N=count
58                     continue
59                 if count==N+1:#删除节点信息
60                     print('已删除节点信息')
61                     continue
62                 f_write.write(line)
63 
64             if N==-2:
65                 print('不存在该节点')
66                 for line in readlines:
67                     f_write.write(line)
68     elif menu=='Q':
69         break
70     else:
71         print('输入不合法')