第一个python实例程序

#!/usr/bin/python2.7

import os
ls = os.linesep

fname = raw_input("fname:");

while True:
        
        if os.path.exists(fname):
                print "Error:'%s' already exists" % fname
        else:
                break

all = []
print "
Enter lines('.' by itself to quit). 
"

while True:
        entry = raw_input('> ')

        if entry == '.':
                break
        else:
                all.append(entry)

fobj = open(fname, 'w')
fobj.writelines(['%s%s' % (x, ls) for x in all])
fobj.close()
print 'DONE!'