yum update with fabric

fabfile.py

#
# $ fab set_hosts update
#

from fabric.api import run, env, sudo
from fabric.contrib.console import confirm

env.warn_only = True

def set_hosts():
    env.hosts = open('hosts', 'r').readlines()

def update():
    print("Executing on %(host)s as %(user)s" % env)
    if run("yum check-update").return_code != 0:
        if confirm("execute yum update?", default=False) == True:
            sudo("yum -y update", pty=True)