Centos 6/7: using needs-restarting after yum update

Install yum utility
# yum install yum-utils

Some update require system to restart or some services to restart. To determine system needs to restart or some services need to restart, run needs-restarting:

# needs-restarting
1512 : /usr/sbin/sshd
609 : /usr/sbin/NetworkManager --no-daemon
615 : /usr/lib/polkit-1/polkitd --no-debug

Tested on Centos 6.9 and Centos 7.3

References: