/********************************************* *                dhcpc * dhcpc是dhcp的客户端，在busybox中实现。今天正好了解一下。 *                    Tony, 2016-5-20, Shenzhen ********************************************/udhcpc -b -i eth0 -p /var/run/udhcpc.pid -R &-b:后台运行-i:指定接口-p:pid文件-R:关闭udhcpc时，可以向dhcpserver发送release取消租约　　Usage: udhcpc [-Cfbnqtvo] [-c CID] [-V VCLS] [-H HOSTNAME] [-i INTERFACE]　　[-p pidfile] [-r IP] [-s script] [-O dhcp-option]... [-P N]　　-V CLASSID      Vendor class identifier　　-i INTERFACE    Interface to use (default: eth0)　　-H,-h HOSTNAME  Client hostname　　-c CLIENTID     Client identifier　　-C              Suppress default client identifier　　-p file         Create pidfile　　-r IP           IP address to request　　-s file         Run file at DHCP events (default /usr/share/udhcpc/default.script)　　-t N            Send up to N request packets　　-T N            Try to get a lease for N seconds (default 3)　　-A N            Wait N seconds (default 20) after failure　　-O OPT          Request DHCP option OPT (cumulative)　　-o              Do not request any options (unless -O is also given)　　-f              Run in foreground　　-b              Background if lease is not immediately obtained　　-S              Log to syslog too　　-n              Exit with failure if lease is not immediately obtained　　-q              Quit after obtaining lease　　-R              Release IP on quit　　-P N            Use port N instead of default 68　　-a              Use arping to validate offered address