How to redirect stdout

# w  w w .  j a v  a2  s  .co m
import sys
sys.stdout = open('log.txt', 'a')      
print 1                                

temp = sys.stdout                     
sys.stdout = open('log.txt', 'a')     
print 'spam'                          
print 1, 2, 3 
sys.stdout.close(  )                  
sys.stdout = temp                     

print 'back here'                     
print open('log.txt').read(  )