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Add hosts entry using python

#Task : To add hosts entry to a server hosts file using python script.
# To whomsoever wondering why, this is a task which can be easily achieved via shell script, but I went forward with Python to learn python.

#Script to change the remote IP across the hosts file.
#How to run this script : python scriptname IP_that_we_need_to_set_hosts_entry
#Importing system library for passing arguments during runtime to incorporate as a jenkins job.
import sys

#The function add_remote add the remote entry to the hosts file and shows us the new entry that we added.
def add_remote():
 with open("/etc/hosts", "a") as myfile:
  myfile.write( str(entered_IP) + ' remote_server_hostname' + '\n' )
 with open("/etc/hosts", "r") as myfile:
  for line in myfile.readlines():
   if 'remote_server_hostname' in line:

#The function fun checks if the hosts entry for remote is added in the server. [Main function]
def fun():
 if 'remote_server_hostname' in open('/etc/hosts').read():
  print("Entry exists and is shown below...!!")
 for line in open("/etc/hosts"):
    if "remote_server_hostname" in line:
     print line,
  print("Going to add the entry for remote...!!")

print "+++++++++++++++++++++++++++++++++====================++++++++++++++++++++++++++++++++"       
print 'The IP that we are going to add in this server as remote IP is', str(sys.argv[1])
global entered_IP
entered_IP = str(sys.argv[1]) #Global Parameter.

for line in open("/etc/hosts"):
 if "remote_server_hostname" in line:
  global existing_IP
  existing_IP = str(line.split()[0]) #Global Parameter           
print '\t \t \t \t Checking the hosts entry now...!! \t \t'
print '.........+++++...........++++....................+++++...........++++....................+++++...........++++...........'

#The function which check if the entered IP is same as the existing remote IP on the server.
def dup_remote():
 global existing_IP
 global entered_IP
 print 'The existing IP for remote in this server is --->', existing_IP
 print 'The new IP that we need to add on this server is --->', entered_IP
 print '==================================================================='
 if entered_IP == existing_IP:
  sys.exit("We already have the new IP in the hosts file for remote. We are stopping the execution of this script now. Thank you...!!")
  print 'We are going to add the new remote IP now...!! Thanks..!'
  print "++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"
  file = open("/etc/hosts", "r")
  readed_lines = file.readlines()
  file = open("/etc/hosts","w")
  for line in readed_lines:
   if 'remote_server_hostname' not in line:


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