lsof is a command meaning "list open files", which is used in many Unix-like systems to report a list of all open files and the processes that opened them.
This command will not be there in Centos7/RHEL7 by default. We can install the same manually by the following steps.
Step1: Log into your Linux server via SSH as root.
Step2: Install lsof package on the server
#yum install lsof