utilize [FILE] option of grep command

On branch master
Changes to be committed:

	modified:   init.sh
	modified:   scripts/aliases.sh
	modified:   scripts/firewalld.sh
	modified:   scripts/lemp.sh
	modified:   scripts/linux_update.sh
	modified:   scripts/middleman.sh
	modified:   scripts/nginx_config.sh
	modified:   scripts/server_ssh.sh
	modified:   scripts/swap.sh
	modified:   setup.sh
	modified:   sudoers.sh