5.18-笨办法学python-习题17（文件拷贝）

from sys import argv
from os.path import exists
#又import了一个命令exists,这个命令将文件名字符串作为参数，如果文件存在返回TRUE,否则返回FALSE

script,from_file,to_file=argv
#传参，不过没有管exists哎

print("copying from %s to %s "%(from_file,to_file))
#打印copying from "from_file"to "to_file"

get=open(from_file)
#打开“from_file”并传递给对象get
indata=get.read()
#读文件然后传给indata

print("the input file is %d bytes long"%len(indata))
#打印the input file is “一个数字”bytes long
print("does the output file exist?%r"%exists(to_file))
#打印does the output file exist?+true/false(有就是true)
print("ready,hit RETURN to continue ,CTRL-C to abort.")
#打印ready,hit RETURN to continue ,CTRL-C to abort.
input('<')
#一个提示符
output=open(to_file,'w')
#以只写的模式打开“to_file”
output.write(indata)
#把indata里的内容（from_file）写进output(to_file)

print("alright,all done")
#打印alright,all done
output.close()
#关闭output
get.close()
#关闭get
copied=open("copied.txt")
print(copied.read())
#查看文件咯