更改文件，某一行

def fetch(data):
    print('这是查询功能')
    tag = False
    data = 'aaaa %s\n'%data
    res_data = []
    with open('bbb','r',encoding='gbk') as file:
        for i in file:
            if i == data:
                tag = True
                continue
            if tag == True and i.startswith('aaa'):
                break
            if tag == True:
                res_data.append(i)
                print(i)
    return res_data
def add():
    pass
def delete():
    pass
def change(data):
    print('你要更改的数据是%s'%data)
    old_addr =data[0]['backend']
    old_to = "        server  %s  98798  %s\n"%(data[0]['record']['server'],data[0]['record']['98798'])
    need_to = "        server  %s  98798  %s\n"%(data[1]['record']['server'],data[1]['record']['98798'])
    res = fetch(old_addr)
    print(res)
    if old_to in res:
        a = res.index(old_to)
        res[a] = need_to
        res.insert(0,'aaaa %s\n'%old_addr)
        tag = False
        write_or = True
        old_addr2 = 'aaaa %s'%old_addr
        with open('bbb','r') as old_file,\
                open('bbb_new','w') as new_file:
            for backend in old_file:
                if backend.strip() == old_addr2:
                    tag = True
                    continue
                elif backend.startswith('aaaa'):
                    tag = False
                if not tag:
                    new_file.write(backend)
                if tag and write_or:
                    for i in res:
                        new_file.write(i)
                    write_or = False

    else:
        print('没有要修改的数据')
    return '更改成功'

if __name__ =="__main__":
    msg = '''
    1：查询
    2；增加
    3：删除
    4：更改
    5：退出'''
    func_list = {
        '1':fetch,
        '2':add,
        '3':delete,
        '4':change
    }
    while True:
        print(msg)
        choice = input("请输入需要选择的功能：")
        if not choice: continue
        if choice =='5':break
        data = input('请输入数据：')
        if choice != '1':
            data = eval(data)
        ress = func_list[choice](data)
        print(ress)
输出：
    1：查询
    2；增加
    3：删除
    4：更改
    5：退出
请输入需要选择的功能：4
请输入数据：[{'backend':'www.asia.com','record':{'server':'jdfjsk','98798':'sajdfkjahskjf'}},{'backend':'www.asia.com','record':{'server':'aaaaa','98798':'bbbbbb'}}]
你要更改的数据是[{'backend': 'www.asia.com', 'record': {'server': 'jdfjsk', '98798': 'sajdfkjahskjf'}}, {'backend': 'www.asia.com', 'record': {'server': 'aaaaa', '98798': 'bbbbbb'}}]
这是查询功能
        server  jdfjsk  98798  sajdfkjahskjf

        server  jdfjsdsk  98798  sajdfksasjahskjf

        server  jdfsdjsk  98798  sajdfksdjahskjf

        server  jdfxcjsk  98798  sajdfkjsaahskjf

        server  jdfjsxck  98798  sajdfkxxzjahskjf

['        server  jdfjsk  98798  sajdfkjahskjf\n', '        server  jdfjsdsk  98798  sajdfksasjahskjf\n', '        server  jdfsdjsk  98798  sajdfksdjahskjf\n', '        server  jdfxcjsk  98798  sajdfkjsaahskjf\n', '        server  jdfjsxck  98798  sajdfkxxzjahskjf\n']
None