dhcp

can I request for an ipaddress through dhcp client by sending ipaddress as input during the invokation of dhcpclient so that it requests the server for the same,instead of depending on the configuration file .

this would be a security risk... so no!

Good point duke, thanks for your response.
I still have one more doubt like , in case of configuration file also, previous ip address is requested ? if we are doing that through configuration file , why not through inputting manually.

i want to invoke dhcpcd application when interface comes up(not system boot,when we plug ethernet cable). how to do that using c language(linux)