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Current user name



Introduction

UserID(useridentifier,UserIDorUID),thefullnameuseridentifier,inUNIX-likesystems,isanunsignedintegervalueusedbythekerneltoidentifyusers,anditisalsooneofthenecessarycomponentsoftheUNIXfilesystemandprocesses.Indifferentsystems,theUIDvaluerangeisdifferent,butgenerallyspeaking,UIDisrepresentedbya15-bitinteger,anditsrangeiswithin0~32767,andtherearethefollowingrestrictions:theUIDofthesuperuserisalways0;UIDswithvalues​​intherangeof1to100arereservedforsystemuse.Somemanualsrecommendtoreserve101to499,oreven101to999(suchasDebian[1])UIDsforbackup;Correspondingly,whenthefirstuseriscreatedwiththeuseraddcommandinLinux,theUIDassignedtoitbydefaultis1000.

ThecurrentusernamereferstotheusernameoruserIDofthecomputercurrentlybeingused.Nowthesystemisgenerallyamulti-usersystem,suchasUNIXOS,LinuxOS.Therefore,theusernameoruserIDofdifferentusersisdifferent,andtheusernamecorrespondstotheuserIDonetoone,whichisusedtodetectwhethertheusernameexistsinthecurrentsystem.Sometimesinordertoknowhowmanyusersareusingthecurrentsystem,itisusuallybyqueryingthecurrentusername.Youcanlearnaboutthecurrentsystemresourceusagethroughthecurrentusername.

Commonmulti-useroperatingsystems

Multi-useroperatingsystemsallowmultipleuserstousethesamemachinethroughtheirownterminals,sharingvariousresourcesinthehostsystem,andeachuserprogramItcanbefurtherdividedintoseveraltasks,sothattheycanbeexecutedconcurrently,whichcanfurtherimproveresourceutilizationandsystemthroughput.Mostofthelarge,medium,andminicomputersareconfiguredwithmulti-userandmulti-taskoperatingsystems,andon32-bitmicrocomputers,manyofthemareconfiguredwithmulti-userandmulti-taskoperatingsystems.

UNIXOS

UNIXOSwasdevelopedbyBellLabsofAmericanTelegraphandTelephoneCompanybetween1969and1970.TheUNIXV.7introducedin1979hasbeenwidelyusedAvarietyofmediumandsmallcomputers.Withtheimprovementofmicrocomputerperformance,peopletransplantedUNIXtomicrocomputer.Around1980,theseventhversionofUNIXwasportedtoMotorola'sMC680xxmicrocomputer.Later,theversionofUNIXV7.0wassimplifiedandthenportedtoIntel8080,whichwascalledXenix.ThetwomostinfluentialvariantsofUNIXoperatingsystemsthatcanrunonmicrocomputersareSolarisOSandLinuxOS.

SolarisOS

SunOS1.0,launchedbySUNin1982,isaUNIXOSrunningontheMotorola680x0platform.SUNOS4.0announcedin1988migratedtheoperatingplatformfromtheearlyMotorola680x0platformtotheSPARCplatform,andbegantosupportIntel’sIntel80x86;in1992,SUNreleasedSolaris2.0.Since1998,Sunhasintroduced64-bitoperatingsystemsSolaris2.7and2.8.Theseoperatingsystemshavegreatlyimprovednetworkfeatures,interoperability,compatibility,andeaseofconfigurationandmanagement.

LinuxOS

LinuxisanimportantvariantofUNIX,originallydevelopedbyFinnishstudentLinusTorvaldsforIntel80386.In1991,thefirstLinuxversionwasreleasedontheInternet.Becausethesourcecodewasopen,manypeoplecooperatedwithitthroughtheInternet,andtheperformanceofLinuxwasrapidlyimproved,anditsapplicationscopewasalsoexpandingdaybyday.Correspondingly,thesourcecodehasalsoexpandedrapidly.Atthistime,itisalreadyafullyfunctionalUNIXsystem.AlargenumberofsoftwarerunningonUNIX(includingmorethan1,000utilitysoftwareandalargenumberofnetworksoftware)havebeentransplantedtoLinux,anditcanbeRunonthemaincomputer,suchasIntel80x86Pentium,etc.

Linuxcommandtoviewusername

inuxviewusercommandwcommand

Thiscommandisusedtodisplaythestatusofusersloggedintothesystem.Thewcommandispowerful,Itcannotonlyshowwhoisloggedintothesystem,butalsoshowthecurrentworkoftheseusers,andthestatisticaldataismoredetailedandscientificthanthewhocommand.

ThedisplayitemsofthewcommandareinthefollowingorderArrangement:thecurrenttime,thetimefromwhenthesystemwasstartedtothepresent,thenumberoflogged-inusers,andtheaverageloadofthesysteminthelast1second,5seconds,and15seconds.Thentherearethevariousdataofeachuser.Thedisplayorderoftheitemsisasfollows:loginaccount,terminalname,remotehostname,logintime,idletime,JCPU,PCPU,andthecommandlineofthecurrentlyrunningprocess.

JCPUtimereferstothetimetakenbyallprocessesconnectedtotheterminal(tty).Thistimedoesnotincludethepastbackgroundjobtime,butitincludesthetimeoccupiedbythecurrentlyrunningbackgroundjob.ThePCPUtimereferstothetimetakenbythecurrentprocess(thatis,theprocessdisplayedintheWHATitem).Thespecificusageandparametersofthiscommandaredescribedbelow.

Linuxviewingusercommandwhocommand

Thiscommandismainlyusedtoviewthecurrentonlineusersituation.Thiscommandisveryuseful.Iftheuserwantstoestablishinstantcommunicationwithotherusers,suchasusingthetalkcommand,thefirstthingtomakesureisthattheuserisindeedonline,otherwisethetalkprocesscannotbeestablished.Foranotherexample,ifthesystemadministratorwantstomonitorwhateachlogged-inuserisdoingatthismoment,hemustalsousethewhocommand.

loginname:loginusername;

terminalline:useterminalequipment;

logintime:logintimetothesystem.

Thefollowingdescribesthecommonlyusedparametersofthewhocommand.

-m

Itdisplaysyourusernameinthesystem,loginterminal,logintime

-q

onlyDisplaytheuser'sloginaccountandthenumberoflogged-inusers

-s

Ignore,itisthesameaswho

-r

CanbeviewedThecurrentsystemrunlevel

run-level3Apr2109:37last=S

-H,--headingdisplaysarowandcolumnheadings.CommonlyusedheadingsareshowninTable4-2.

Linuxviewusercommandlast

Youcanviewthelasttimeyouloggedin.Ofcourse,rootcanviewtheloginstatusofotherusers.

last-nusercanseethepreviousnloginsofuser

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