udhcpc

/*********************************************
 *                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