ex16.py

from sys import argv

script, filename = argv

print "We're going to erase %r." % filename
print "If you don't want that, hit CTRL-C(^C)."
print "If you fo want that,hit RETURN."

raw_input("?")

print "Opening the file..."
target = open(filename,'w') #this is for open the file in write mode
#target = open(filename)

print "Truncating the file. Goodbye!"
target.truncate() #truncating the file content

print "Now I'm going to ask you for three lines."

line1 = raw_input("line 1: ")
line2 = raw_input("line 2: ")
line3 = raw_input("line 3: ")

print "Now I'm going to write these to the file."

target.write(line1)
target.write("\n")
target.write(line2)
target.write("\n")
target.write(line3)
target.write("\n")

print "And finally,we close it."
target.close()

print "reopen the file and print it."
reopen = open(filename)
print reopen.read()
reopen.close()