How do I start / stop or restart lighttpd web server under Linux / UNIX operating systems?

Most Linux distro includes lighttpd control script. Try following as per your distribution / UNIX version.

CentOS / Fedora / RHEL Linux – Start lighttpd

# /etc/init.d/lighttpd start
OR systemd based CentOS/RHEL 7.x & Fedora Linux latest:
# systemctl start lighttpd

CentOS / Fedora / RHEL Linux – Stop lighttpd

# /etc/init.d/lighttpd stop
OR systemd based CentOS/RHEL 7.x & Fedora Linux latest:
# systemctl stop lighttpd

CentOS / Fedora / RHEL Linux – Restart lighttpd

# /etc/init.d/lighttpd restart
OR systemd based CentOS/RHEL 7.x & Fedora Linux latest:
# systemctl restart lighttpd