Dhcpcd is a DHCP client daemon that adheres to RFC2131, RFC2132, and RFC1541 standards.
To get a detailed description of this client daemon's command-line options, I looked through the dhcpcd man page. Its stable version, dhcpcd-1.3, has been reportedly compiled and utilised in various Linux platforms based on Intel, PowerPC, and Alpha architectures. It requires glibc-2.0.5 or later to be installed.
One must invoke the dhcpcd client by typing 'dhcpcd' in the console. However, no explicit '&' character is required to put it in the background. Background processing is automatic except when dhcpcd was compiled using the -DDEBUG flag. As soon as the interface is configured, dhcpcd automatically forks into the background.
By default, dhcpcd attaches to 'eth0', except when a user wishes to provide an interface name explicitly in the command line. To provide a demonstration of its usage, here is an example where I used it on a Linux box, serving as a router/firewall for the local network 192.168.12.0.
Version 5.0.6: N/A