ubuntu restart network (eth0 dhcp)

restart networking

/etc/init.d/networking  restart 

/etc/network/

# The primary network interface
auto eth0
iface eth0 inet dhcp
~                       

root@jqt-laptop:/etc/network# ls
 if-down.d  if-post-down.d  if-pre-up.d  if-up.d  interfaces  interfaces.bak-0
root@jqt-laptop:/etc/network# 
root@jqt-laptop:/etc/network#