python中向文本中写入文字与按行读取

# 文件写入且覆盖
# file = open(filename, 'w', encoding='utf-8')
# 文件写入且不覆盖
file = open(filename, 'a', encoding='utf-8')
file.write(data2)
file.close

import linecache

file = open(filename, 'r', encoding='utf-8')
# 文件数据总行数
linecount = len(file.readlines())
# 取倒数第一行数据
data = linecache.getline(filename, linecount)