python中sys模块的argv

"""笨办法学python，启动时在命令行中python 脚本文件名 filename"""
from sys import argv

# argv  - 命令行参数; argv[0]是脚本路径名python,sys.argv[0]表示脚本路径名
script, filename = argv         # 脚本和文件名称
print("We're going to erase %r." % filename)    # 正常使用%s，在这里%r是为了重现它代表的对象
print("If you don't want that, hit RETURN-C (^C).")
print("If you do want that, hit RETURN.")
input("?")                  # 单纯的？号
print("Opening the file...")
target = open(filename, "w")    # 以"w"写入的形式打开文件，a表示追加，r表示读取。不写默认是读取操作
print("Truncating the file. Goodbye!")
target.truncate()           # 清除之前的数据
print("Now I'm going to ask you for three lines.")
line1 = input("line 1: ")       # 获取用户输入
line2 = input("line 2: ")
line3 = input("line 3: ")
print("I'm going to write these to the file.")
target.write(line1)             # 写入用户输入
target.write("
")
target.write(line2)
target.write("
")
target.write(line3)
target.write("
")
print("And finally, we close it.")
target.close()              # 关闭已打开的文件