wcl命令,用shell脚本设定crontab命令

如何使用Linux命令dhclient

theinternetsystemsconsortiumdhcpclient、dhclient、providesameansforconfiguringoneormorenetworkinterfacesusingthedynamichost是or if these protocols fail，by statically assigning an address。

Linux客户端语法

h客户端[-pport ] [-d ] [-evar=value ] [-q ] [-1 ] [-r ] [-lf lease-file ] [-pf PID-file ] [-cf config-] [ if0 [ . IFN ]-pportifthedhcpclientshouldlistenandtransmitonaportotherthanthestandard (port 68 )， the-pflagmayused.itshouldbefollowedbytheudpportnumberthatdhclientshoulduse.thisismostlyusefulfordebuggingpurposes.ifadpurpurposes toListenonandTransmiton，theclientwillalsouseadifferentdestinationport-onegreaterthanthespecicified

- sthedhcpclientnormallytransmitsanyprotocolmessagesitsendsbeforeacquiringanipaddressto，255.255.255，theiplimitedbroadcadcto itmaybeusefultohavetheservertransmitthesemessagestosomeotheraddress.thiscanbespecifiedwiththe-sflag，folllowedbytheipadredresthe

-gFor testing purposes，thegiaddrfieldofallpacketsthattheclientsendscanbesetusingthe-gflag，followedbytheipaddresstosend. andshouldnotbeexpectedtoworkinanyconsistentorusefulway。

- dthedhcpclientwillnormallyrunintheforegrounduntilithasconfiguredaninterface， andthenwillreverttorunninginthebackground.torunforcedhclienttoalwaysrunasaforegroundprocess， the-dflagshouldbespecified.thisisusefulwhenrunningtheclientunderadebugger，orwhenrunningitoutofinittabonsystemvsystems。

- ethedhclientdaemoncreatesitsownenvironmentwhenexecutingthedhclient-scripttodothegruntworkofinterfaceconfiguration.tode fied sandtheirvalues，use the -e flag，followedbytheenvironmentvariablenameandvalueasignment，Justasonewouldassignment

- rtheclientnormallydoesn ' treleasethecurrentleaseasitisnotrequiredbythedhcpprotocol.somecableispsrequiretheirclientsttononotionotocol eanassignedipaddress.the-rflagexplicitlyreleasesthecurrentlease，and once the lease has been released，

-1the-1 flagcausedhclienttotryoncetogetalease.ifit fails，dhclient exits with exit代码two。

-cf、-lf、-pf、and-sfthedhcpclientnormallygetsconfigurationinformationfrom/etc/DHCP3/dhclient.conf， itsleasedatabasefrom/var/lib/DHCP3/dhclient.leases，storesitsprocessidinafilecalled/var/run/dhclient.PID， andconfiguresthenetworkinterfaceusing/sbin/dhclient-scripttospecifydifferentnamesand/orlocationsforthesefiles，use the followedbythenameofthefile.thiscanbeparticularlyusefulif，for example，/var/lib/DHCP3or/var/runhasnotyetbeenmountented

- wthedhcpclientnormallyexitsifitisn ' tabletoidentifyanynetworkinterfacestoconfigure.onlaptopcomputersandothercomputerswith itispossiblethatabroadcastinterfacemaybeaddedaftersystemstartup.the-wflagcanbeusedtocausetheclientnottoexitwhenitdoesn ' t ll(1) programcanthenbeusedtonotifytheclientwhenanetworkinterfacehasbeenaddedorremoved，sothattheclientcanatttempttoconfigural

- nthedhcpclientcanbedirectednottoattempttoconfigureanyinterfacesusingthe-nflag.thisismostlikelytobeusefulincombinationwition

- nwtheclientcanalsobeinstructedtobecomeadaemonimmediately，ratherthanwaitinguntilithasacquiredanipaddress.thiscanbedonebysed

- etheclientrunschildprocesses (scripts ) withacleanenvironment.use the-eflagtospecifyadditionalenvironmentvariablestopass

linux dhclient演示示例：

dhclient eth0

重新创建IP地址。