Copying from one text file to another using Python

Question

I would like to copy certain lines of text from one text file to another. In my current script when I search for a string it copies everything afterwards, how can I copy jus

Answer 1

f=open('list1.txt')  
f1=open('output.txt','a')
for x in f.readlines():
    f1.write(x)
f.close()
f1.close()

this will work 100% try this once