dhcpd --version (return code: 0)
isc-dhcpd-4.3.5
dhcpd -HELP (return code: 1)
Internet Systems Consortium DHCP Server 4.3.5
Copyright 2004-2016 Internet Systems Consortium.
All rights reserved.
Unknown command --help
Usage: dhcpd [-p <UDP port #>] [-f] [-d] [-q] [-t|-T]
[-4|-6] [-cf config-file] [-lf lease-file]
[-user user] [-group group] [-chroot dir]
[-tf trace-output-file]
[-play trace-input-file]
[-pf pid-file] [--no-pid] [-s server]
[if0 [...ifN]]
If you think you have received this message due to a bug rather
than a configuration issue please read the section on submitting
bugs on either our web page at www.isc.org or in the README file
before submitting a bug. These pages explain the proper
process and the information we find helpful for debugging..
exiting.