top 100 linux interview questions and answers 2014

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hirist .com www.hirist.com TOP 100 INTERVIEW QUESTIONS & ANSWERS LINUX

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If you're looking for the top 100 linux interview questions and answers, then you've come to the right place. We at hirist have compiled a list of the top linux interview questions that are asked by companies like TCS, Infosys, Wipro, HCL and Cognizant and put it together in a pdf format that can be downloaded for free. You can easily download this free linux interview questions pdf file and use it to prepare for an interview. It doesn't matter if you're looking for linux interview questions and answers for freshers or linux interview questions and answers for experienced because this presentation will cater to both segments. This list includes Linux interview questions and answers in the below categories: top 100 linux interview questions kickstart linux interview questions interview questions on linux boot process top 100 linux interview questions answers linux interview questions 2009 linux installation interview questions interview question on linux commands linux interview topics top 50 linux interview questions Top 30 linux system admin interview questions & answers Top 25 Unix interview questions with answers Linux Interview Questions Practical Interview Questions and Answers on Linux Top 100 Informatica Interview Questions 10 Linux and UNIX Interview Questions and Answers linux interview questions and answers for freshers linux interview questions and answers pdf linux interview questions and answers pdf free download linux interview questions and answers for experienced pdf linux l2 interview questions and answers linux system administrator interview questions and answers basic linux interview questions and answers red hat linux interview questions and answers

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  • 1. hirist .com www.hirist.com TOP 100 INTERVIEW QUESTIONS & ANSWERS LINUX
  • 2. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisLinuxandwhyisitsopopular? 2 QUESTION LinuxisanoperatingsystembasedonUNIX,andwasfirstintroducedbyLinusTorvaldscommonlyusedinservers. ItisbasedontheLinuxKernel,andcanrunondifferenthardwareplatformsmanufacturedbyIntel,MIPS,HP, IBM,SPARCandMotorola.AnotherpopularelementinLinuxisitsmascot,apenguinfigurenamedTux. PopularityofLinuxisbecauseofthefollowingreasons Itisfreeandopensource.WecandownloadLinuxforfreeandcustomizeitasperourneeds. Itisveryrobustandadaptable. Immenseamountoflibrariesandutilities ANSWER QUESTION 1
  • 3. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisBASH? 3 QUESTION BASHisshortforBourneAgainSHell.ItwaswrittenbySteveBourneasareplacementtotheoriginalBourneShell(representedby/bin/sh).ItcombinesallthefeaturesfromtheoriginalversionofBourneShell,plusadditionalfunctionstomakeiteasierandmoreconvenienttouse.IthassincebeenadaptedasthedefaultshellformostsystemsrunningLinux. ANSWER QUESTION 2
  • 4. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthecoreofLinuxOperatingSystem? 4 QUESTION ThecoreoftheLinuxoperatingsystemisKernel.ItisbrokendownintoShell,Command,Script,andTerminal.ShellisacommandLineInterpreter,CommandisuserInstructiontoComputer,Scriptiscollectionofcommandsstoredinafile,andTerminalisacommandLineInterface. ANSWER QUESTION 3
  • 5. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthebasicdifferencebetweenUNIXandLinuxOperatingSystem? 5 QUESTION Linuxisfreeandopen-sourcesoftware(allowingprogrammerstoprogramwithLinuxnotaroundit),thekernelofwhichiscreatedbyLinusTorvaldsandcommunity.UNIX,ontheotherhand,isUNIXiscopyrightednameonlybigcompaniesareallowedtousetheUNIXcopyrightandname,soIBMAIXandSunSolarisandHP-UXallareUNIXoperatingsystems. ANSWER QUESTION 4
  • 6. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisLILO? 6 QUESTION LILOisabootloaderforLinux.ItisusedmainlytoloadtheLinuxoperatingsystemintomainmemorysothatitcanbeginitsoperations. ANSWER QUESTION 5
  • 7. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisanINODE? 7 QUESTION Allfileshaveitsdescriptionstoredinastructurecalledinode.Theinodecontainsinfoaboutthefile-size,accessandmodificationtime,permissionandsoon.Inadditiontodescriptionsaboutthefile,theinodecontainspointerstothedatablocksofthefile. ANSWER QUESTION 6
  • 8. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisaswapspace? 8 QUESTION AswapspaceisacertainamountofspaceusedbyLinuxtotemporarilyholdsomeprogramsthatarerunningconcurrently.ThishappenswhenRAMdoesnothaveenoughmemorytoholdallprogramsthatareexecuting. ANSWER QUESTION 7
  • 9. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatistheadvantageofopensource? 9 QUESTION Opensourceallowsyoutodistributeyoursoftware,includingsourcecodesfreelytoanyonewhoisinterested. Peoplewouldthenbeabletoaddfeaturesandevendebugandcorrecterrorsthatareinthesourcecode.Theycanevenmakeitrunbetter,andthenredistributetheseenhancedsourcecodefreelyagain.Thiseventuallybenefitseveryoneinthecommunity. ANSWER QUESTION 8
  • 10. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthebasicdifferencebetweenBASHandDOS? 10 QUESTION ThekeydifferencesbetweentheBASHandDOSconsoleliesin3areas: -BASHcommandsarecasesensitivewhileDOScommandsarenot; -underBASH,/characterisadirectoryseparatorandactsasanescapecharacter.UnderDOS,/servesasacommandargumentdelimiterandisthedirectoryseparator -DOSfollowsaconventioninnamingfiles,whichis8characterfilenamefollowedbyadotand3characterfortheextension.BASHfollowsnosuchconvention. ANSWER QUESTION 9
  • 11. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthedifferencebetweenTCPandUDP? 11 QUESTION ThebasicdifferenceisthatTCPestablishesaconnectionbeforesendingdataandthisallowsittocontrolthedataflowandguaranteethatallpacketsgetdelivered.UDPsimplychucksdatagramsontothewireandifsomegetlostorarriveinbadordertheresnowaytorequestaresend.HoweverUDPhaslownetworkoverheadsosomeservicessuchasDNSresolution,SNMP,DHCP,RIPandVOIPuseUDPforitsspeedandanyerrorsareusuallydealtwithontheapplicationlayerratherthannetworklayer. ANSWER QUESTION 10
  • 12. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatistheimportanceoftheGNUproject? 12 QUESTION Thisso-calledFreesoftwaremovementallowsseveraladvantages,suchasthefreedomtorunprogramsforanypurposeandfreedomtostudyandmodifyaprogramtoyourneeds.Italsoallowsyoutoredistributecopiesofasoftwaretootherpeople,aswellasfreedomtoimprovesoftwareandhaveitreleasedtothepublic. ANSWER QUESTION 11
  • 13. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowdoesDNSresolutionwork? 13 QUESTION AclientapplicationrequestsanIPaddressfromthenameserverusuallybyconnectingtoUDPport53.ThenameserverwillattempttoresolvetheFQDNbasedonitsresolverlibrary,whichmaycontainauthoritativeinformationaboutthehostrequestedorcacheddataaboutthatnamefromanearlierquery.Ifthenameserverdoesnotalreadyhavetheanswer,itwillturntorootnameserverstodeterminetheauthoritativefortheFQDNinquestion. Then,withthatinformation,itwillquerytheauthoritativenameserversforthatnametodeterminetheIPaddress. ANSWER QUESTION 12
  • 14. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Describetherootaccount. 14 QUESTION Therootaccountislikeasystemsadministratoraccount,andallowsyoufullcontrolofthesystem.Hereyoucancreateandmaintainuseraccounts,assigningdifferentpermissionsforeachaccount.ItisthedefaultaccounteverytimeyouinstallLinux. ANSWER QUESTION 13
  • 15. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisCLI? 15 QUESTION CLIisshortforCommandLineInterface.Thisinterfaceallowsusertotypedeclarativecommandstoinstructthecomputertoperformoperations.CLIoffersanadvantageinthatthereisgreaterflexibility.However,otheruserswhoarealreadyaccustomwithusingGUIfinditdifficulttoremembercommandsincludingattributesthatcomewithit. ANSWER QUESTION 14
  • 16. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisGUI? 16 QUESTION GUI,orGraphicalUserInterface,makesuseofimagesandiconsthatusersclickandmanipulateasawayofcommunicatingwiththecomputer.Insteadofhavingtorememberandtypecommands,theuseofgraphicalelementsmakesiteasiertointeractwiththesystem,aswellasaddingmoreattractionthroughimages,iconsandcolors. ANSWER QUESTION 15
  • 17. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowcanyoufindouthowmuchmemoryLinuxisusing? 17 QUESTION Fromacommandshell,usetheconcatenatecommand:cat/proc/meminfoformemoryusageinformation.Youshouldseealinestartingsomethinglike:Mem:64655360,etc.ThisisthetotalmemoryLinuxthinksithasavailabletouse. ANSWER QUESTION 16
  • 18. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisanMXrecord? 18 QUESTION AnMXrecordnumericallyranksthemailserversyouwouldprefertoreceiveemailforadomain.TheMXrecordwiththelowestnumberispreferredovertheothers,butyoucansetmultipleemailserverswiththesamevalueforsimpleloadbalancing. ANSWER QUESTION 17
  • 19. For the hottest LINUX jobs, please visit www.hirist.com hirist .com PleasedescribetheLinuxboot-upsequence. 19 QUESTION Therearesevenstepstotheboot-upsequence.1)BIOS(basicinput/outputsystem)executestheMBRwhereBootLoadersits,2)MBR-MasterbootreadsKernelintomemory,3)GRUB(GrandUnifiedBootloader)KernelstartsInitprocess,4)KernelKernelexecutesthe/sbin/initprogram.Initreadsinittab,executesrc.sysinit,5)Initthercscriptthanstartsservicestoreachthedefaultrunleveland6)Runlevelprogramstheseprogramsareexecutedfrom/etc/rc.d/rc*.dl/ ANSWER QUESTION 18
  • 20. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatistypicalsizeforaswappartitionunderaLinuxsystem? 20 QUESTION Thepreferredsizeforaswappartitionistwicetheamountofphysicalmemoryavailableonthesystem.Ifthisisnotpossible,thentheminimumsizeshouldbethesameastheamountofmemoryinstalled. ANSWER QUESTION 19
  • 21. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Howdoyousearchforapatternandthenreplaceitinanentirefile? 21 QUESTION YouuseSed,orinVieditor,thesearchusescharactersslashthepatterntobesearched,slashthepatterntoreplaceitwith,slashgwhichstandsforentirefile. ANSWER QUESTION 20
  • 22. For the hottest LINUX jobs, please visit www.hirist.com hirist .com DoestheCtrl+Alt+DelkeycombinationworkonLinux? 22 QUESTION Yes,itdoes.JustlikeWindows,youcanusethiskeycombinationtoperformasystemrestart.Onedifferenceisthatyouwontbegettinganyconfirmationmessageandtherefore,rebootisimmediate. ANSWER QUESTION 21
  • 23. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowdoyoulistandflushallIptables? 23 QUESTION FirstyouusetheLswitchtoviewallthecurrentlypresentrulesandthenFtoflushthem. ANSWER QUESTION 22
  • 24. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowdoyouchangepermissionsunderLinux? 24 QUESTION Assumingyouarethesystemadministratorortheownerofafileordirectory,youcangrantpermissionusingthechmodcommand.Use+symboltoaddpermissionorsymboltodenypermission,alongwithanyofthefollowingletters:u(user),g(group),o(others),a(all),r(read),w(write)andx(execute).Forexamplethecommandchmodgo+rwFILE1.TXTgrantsreadandwriteaccesstothefileFILE1.TXT,whichisassignedtogroupsandothers. ANSWER QUESTION 23
  • 25. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisashell?Whataretheirnames? 25 QUESTION Theshellisthepartofthesystemwithwhichtheuserinteracts.AUnixshellinterpretscommandssuchaspwd, cdortracerouteandsendstheproperinstructionstotheactualoperatingsystemitself.TheshellscurrentlyavailableareAnsSH,BASH,CSH,TCSH,NOLOGIN,KSH.Otherfunctionsofashellincludescriptingcapability, pathmemory,multitasking,andfilehandling. ANSWER QUESTION 24
  • 26. For the hottest LINUX jobs, please visit www.hirist.com hirist .com InLinux,whatnamesareassignedtothedifferentserialports? 26 QUESTION Serialportsareidentifiedas/dev/ttyS0to/dev/ttyS7.ThesearetheequivalentnamesofCOM1toCOM8inWindows. ANSWER QUESTION 25
  • 27. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisazombie? 27 QUESTION Cheekyanswersgetbonuspointsforthisone.ButintheLinuxworld,azombieprocessistheprocessoutputofps bythepresenceofZintheSTATcolumn.Zombiesareessentiallytheprematureprocesseswhosematureparentprocessesdiedwithoutreapingitschildren.Notethatzombiescantbekilledwiththeusualkillsignal. ANSWER QUESTION 26
  • 28. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowdoyouaccesspartitionsunderLinux? 28 QUESTION Linuxassignsnumbersattheendofthedriveidentifier.Forexample,ifthefirstIDEharddrivehadthreeprimarypartitions,theywouldbenamed/numbered,/dev/hda1,/dev/hda2and/dev/hda3. ANSWER QUESTION 27
  • 29. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Youneedtodefineamacro,akeybindingfortheexistingcommand.Howwouldyoudoit? 29 QUESTION Thereisacommandcalledbind,inbashshellwhichiscapableofdefiningmacro,orbindingakey.Inordertobindakeywithanexistingcommand,weneedtogenerateCharacterSequenceemittedbythekey.PressCtrl+vandthenkeyF12,Igot^[[24~ ANSWER QUESTION 28
  • 30. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Yourassistantneedstoprintdirectorystack,whatwouldyousuggest? 30 QUESTION TheLinuxcommand'dirs',willprintthedirectorystack. ForExample:[root@localhost~]#dirs /usr/share/X11 ANSWER QUESTION 29
  • 31. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthemaximumlengthforafilenameunderLinux? 31 QUESTION Anyfilenamecanhaveamaximumof255characters.Thislimitdoesnotincludethepathname,sothereforetheentirepathnameandfilenamecouldwellexceed255characters. ANSWER QUESTION 30
  • 32. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatdoesthecommand'hash'isusedforinbashShell? 32 QUESTION Linuxcommand'hash'managesinternalhashtable,finsandrememberfullpathofthespecifiedcommand,Displayusedcommandnamesandnumberoftimesthecommandisused. [root@localhost~]#hash hitscommand 2/bin/ls 2/bin/su ANSWER QUESTION 31
  • 33. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhichbuiltinLinuxcommandperformsarithmeticoperationofIntegersinBash? 33 QUESTION The'let'commandthatperforms,arithmeticoperationofintegerinbashshell. #!/bin/bash ... ... letc=a+b ... ANSWER QUESTION 32
  • 34. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Explainvirtualdesktop. 34 QUESTION Thisservesasanalternativetominimizingandmaximizingdifferentwindowsonthecurrentdesktop.Usingvirtualdesktops,eachdesktopisacleanslatewhereyoucanopenoneormoreprograms.Ratherthanminimizing/restoringallthoseprogramsasneeded,youcansimplyshufflebetweenvirtualdesktopswithprogramsintactineachone. ANSWER QUESTION 33
  • 35. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Differentiatemultiuserfrommultitask. 35 QUESTION Multiusermeansthatmorethanonepersoncanusethecomputeratthesametime.Multitaskmeansthatevenasingleusercanhavethecomputerworkonmorethanonetaskorprogramatthesametime. ANSWER QUESTION 34
  • 36. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Youhavealargetextfile,andyouneedtoseeonepageatatime.Whatwillyoudo? 36 QUESTION Youcanachievetheaboveresultbypipelingtheoutputof'catfile_name.txt'with'more'command. [root@localhost~]#catfile_name.txt|more ANSWER QUESTION 35
  • 37. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whoownthedatadictionary? 37 QUESTION Theuser'SYS'ownsthedatadictionary.Users'SYS'and'SYSEMarecreatedbydefault,automatically. ANSWER QUESTION 36
  • 38. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowdoyoushareaprogramacrossdifferentvirtualdesktopsunderLinux? 38 QUESTION Toshareaprogramacrossdifferentvirtualdesktops,intheupperleft-handcornerofaprogramwindowlookforaniconthatlookslikeapushpin.Pressingthisbuttonwillpinthatapplicationinplace,makingitappearinallvirtualdesktops,inthesamepositiononscreen. ANSWER QUESTION 37
  • 39. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatcommandshouldyouusetocheckthenumberoffilesanddiskspaceusedbyeachuser'sdefinedquotas? 39 QUESTION Thecommand'repquota'comestorescuehere.Commandrepquotasummariesquotasforafilesystem. ANSWER QUESTION 38
  • 40. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whataredaemons? 40 QUESTION Daemonsareservicesthatprovideseveralfunctionsthatmaynotbeavailableunderthebaseoperatingsystem.Itsmaintaskistolistenforservicerequestandatthesametimetoactontheserequests.Aftertheserviceisdone,itisthendisconnectedandwaitsforfurtherrequests. ANSWER QUESTION 39
  • 41. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Youhavelotsofrunningjobs,howwouldyouremovealltherunningprocesses,withoutrestartingthemachine? 41 QUESTION TheLinuxcommand'disown-r'willremovealltherunningProcesses. ANSWER QUESTION 40
  • 42. For the hottest LINUX jobs, please visit www.hirist.com hirist .com AuserisnewtoLinuxandhewantstoknowfulllistofavailablecommands,whatwouldyousuggesthim? 42 QUESTION Acommand'compgenc'willshowafulllistofavailablecommands. [root@localhost~]$compgen-c l. ll ls which if then else elif fi case esac for select while until do done ANSWER QUESTION 41
  • 43. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatarethekindsofpermissionsunderLinux? 43 QUESTION Thereare3kindsofpermissionsunderLinux: -Read:usersmayreadthefilesorlistthedirectory -Write:usersmaywritetothefileofnewfilestothedirectory -Execute:usersmayrunthefileorlookupaspecificfilewithinadirectory ANSWER QUESTION 42
  • 44. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Youneedtotrackeventsonyoursystem.Whatwillyoudo? 44 QUESTION Fortrackingtheeventsonthesystem,weneedadaemoncalledsyslogd.Thesyslogddaemonisusefulintrackingtheinformationofsystemandthensavingittospecifiedlogfiles. Runningsyslogdapplicationinterminalgenerateslogfileatthelocation/var/log/syslog.ThesyslogdapplicationisveryusefulintroubleshootingLinuxsytems.Asamplelogfilelookssimilartobelow. ANSWER QUESTION 43
  • 45. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowwillyourestrictIPsothattherestrictedIPsmaynotusetheFTPServer? 45 QUESTION WecanblocksuspiciousIPbyintegratingtcp_wrapper.Weneedtoenabletheparametertcp_wrapper=YESintheconfigurationfileat/etc/vsftpd.conf.AndthenaddthesuspiciousIPinthehost.denyfileatlocation/etc/host.deny. ANSWER QUESTION 44
  • 46. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatarethedifferentmodeswhenusingvieditor? 46 QUESTION Thereare3modesundervi: -Commandmodethisisthemodewhereyoustartin -Editmodethisisthemodethatallowsyoutodotextediting -Exmodethisisthemodewhereinyouinteractwithviwithinstructionstoprocessafile ANSWER QUESTION 45
  • 47. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Isitpossibletouseshortcutforalongpathname? 47 QUESTION Yes,thereis.AfeatureknownasfilenameexpansionallowsyoudothisusingtheTABkey.Forexample,ifyouhaveapathnamed/home/iceman/assignmentsdirectory,youwouldtypeasfollows:/ho[tab]/ice[tab]/assi[tab].This, however,assumesthatthepathisunique,andthattheshellyoureusingsupportsthisfeature. ANSWER QUESTION 46
  • 48. For the hottest LINUX jobs, please visit www.hirist.com hirist .com TellusthedifferencebetweenTelnetandSSH? 48 QUESTION TelnetandSSHbotharecommunicationprotocolwhichareusedtomanageremotesystem.SSHisSecured,whichrequiresexchangingofkeyoppositeoftelnetwhichtransmitdatainplaintext,whichmeanstelnetislesssecurethanSSH. ANSWER QUESTION 47
  • 49. For the hottest LINUX jobs, please visit www.hirist.com hirist .com YouneedtostopyourXserver.WhenyoutriestokillyourXserver,YougotanerrormessagethatyoucannotquitXserver.Whatwillyoudo? 49 QUESTION WhenkillingaXserver,itwontworknormalwaylikedoing/etc/init.d/gdmstop.WeneedtoexecuteaspecialkeycombinationCtrl+Alt+BackSpacewhichwillforceXservertorestart. ANSWER QUESTION 48
  • 50. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisthedifferencebetweencommandpingandping6? 50 QUESTION Boththecommandsaresameandusedforthesamepurposeexceptthatthefactthatping6isusedwithipv6IPaddress. ANSWER QUESTION 49
  • 51. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisredirection? 51 QUESTION Redirectionistheprocessofdirectingdatafromoneoutputtoanother.Itcanalsobeusedtodirectanoutputasaninputtoanotherprocess. ANSWER QUESTION 51
  • 52. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Youwanttosearchforallthe*.tarfilesinyourHomedirectoryandwantstodeleteallatonce.Howwillyoudoit? 52 QUESTION Weneedtousefindcommandwithrmcommandtodeleteall.tarfiles. #find/home/name'*. tar'|xargsrmrf ANSWER QUESTION 51
  • 53. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisthedifferencebetweenlocateandslocatecommand? 53 QUESTION Theslocatelooksforthefilesthatuserhaveaccesswhereaslocatewillsearchforthefilewithupdatedresult. ANSWER QUESTION 52
  • 54. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatistheSMTP? 54 QUESTION SMTPisthemostcommonprotocolforane-mailserver. ANSWER QUESTION 53
  • 55. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatSambaservicedo? 55 QUESTION TheSambaserviceprovidesMicrosoftSMBsupportinLinuxsothatLinuxmachinescanconnecttoMicrosoftnetworkresources. ANSWER QUESTION 54
  • 56. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhichservicecanbeusedwithNFStoprovideremotefileaccessforUNIXsystems? 56 QUESTION NISisusedwithNFStoprovideremotefileaccessforUNIXsystems. ANSWER QUESTION 55
  • 57. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisMTA? 57 QUESTION MTAisaserviceofSendmailserver,whichtransfermailfromonenetworkorhosttoanothernetworkorhost. ANSWER QUESTION 56
  • 58. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Nameaconnection-lessprotocolforfiletransfer. 58 QUESTION TFTPisaconnection-lessprotocolforfiletransfer. ANSWER QUESTION 57
  • 59. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Youcompanyhaveslowinternetconnection.WhichLinuxserviceyoucanusetomanageinternetconnection? 59 QUESTION YoushoulduseSquidproxyserver,whichallowstomanagethewebcontentsandalsocachethewebpagestodecreasetheamountoftrafficgoingtoInternet. ANSWER QUESTION 58
  • 60. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whichportshouldyouopeninyourhostfirewalltorunwebserver? 60 QUESTION Bydefaultwebserveruseport80and443whichyouneedtoopeninfirewall. ANSWER QUESTION 59
  • 61. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhichIPaddressingshouldyouuseforServer? 61 QUESTION ForserveryoushouldalwaysusestaticIPaddress. ANSWER QUESTION 60
  • 62. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whichportsshouldyouopeninhostfirewallforanemailserver? 62 QUESTION Openport110whichisusedbythePOP3e-mailprotocol. Openport25whichisusedbytheSMTPe-mailprotocol. Openport143whichisusedbytheIMAPe-mailprotocol. ANSWER QUESTION 61
  • 63. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhichIPaddressshouldyouuseforclientdesktop? 63 QUESTION Forclientyoucanusebothstaticanddynamicmethod.ForeasymanagementusingDHCPtoassignIPaddresswouldbethebestoption. ANSWER QUESTION 62
  • 64. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisinitrdimageandwhatisitsfunctioninthelinuxbootingprocess? 64 QUESTION TheinitialRAMdisk(initrd)isaninitialrootfilesystemthatismountedpriortowhentherealrootfilesystemisavailable.Theinitrdisboundtothekernelandloadedaspartofthekernelbootprocedure.Thekernelthenmountsthisinitrdaspartofthetwo-stagebootprocesstoloadthemodulestomaketherealfilesystemsavailableandgetattherealrootfilesystem.Thusinitrdimageplaysavitalroleinlinuxbootingprocess. ANSWER QUESTION 63
  • 65. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Explainthetermssuid,sgidandstickybit? 65 QUESTION InadditiontothebasicfilepermissionsinLinux,therearefewspecialpermissionsthatareavailableforexecutablefilesanddirectories. SUID:Ifsetuidbitisset,whenthefileisexecutedbyauser,theprocesswillhavethesamerightsastheownerofthefilebeingexecuted. SGID:Sameasabove,butinheritsgroupprevilegesofthefileonexecution,notuserprevileges.Similarwaywhenyoucreateafilewithindirectory,itwillinheritthegroupownershipofthedirectories. Stickybit:Stickybitwasusedonexecutablesinlinuxsothattheywouldremaininthememorymoretimeaftertheinitialexecution,hopingtheywouldbeneededinthenearfuture.Butmainlyitisonfolders,toimplythatafileorfoldercreatedinsideastickybitenabledfoldercouldonlybedeletedbytheowner.Averygoodimplementationofstickybitis/tmp,whereeveryuserhaswritepermissionbutonlyuserswhoownafilecandeletethem. ANSWER QUESTION 64
  • 66. For the hottest LINUX jobs, please visit www.hirist.com hirist .com ListoutfewofthedifferencesbetweenSoftlinkandHardlink? 66 QUESTION a)Hardlinkcannotbecreatedfordirectories.Hardlinkcanonlybecreatedforafile. b)Symboliclinksorsymlinkscanlinktoadirectory. c)Removingtheoriginalfilethatyourhardlinkpointstodoesnotremovethehardlinkitself;thehardlinkstillprovidesthecontentoftheunderlyingfile. d)Ifyouremovethehardlinkorthesymlinkitself,theoriginalfilewillstayintact. e)Removingtheoriginalfiledoesnotremovetheattachedsymboliclinkorsymlink,butwithouttheoriginalfile,thesymlinkisuseless ANSWER QUESTION 65
  • 67. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisthedifferencebetweenumaskandulimit? 67 QUESTION umaskstandsforUserfilecreationmask,whichdeterminesthesettingsofamaskthatcontrolswhichfilepermissionsaresetforfilesanddirectorieswhentheyarecreated.Whileulimitisalinuxbuiltincommandwhichprovidescontrolovertheresourcesavailabletotheshelland/ortoprocessesstartedbyit. Youcanlimitusertospecificrangebyediting/etc/security/limits.confatthesametimesystemwidesettingscanbeupdatedin/etc/sysctl.conf ANSWER QUESTION 66
  • 68. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthefunctionalityofaPuppetServer? 68 QUESTION Puppetisanopen-sourceandenterpriseapplicationforconfigurationmanagementtollinUNIXlikeoperatingsystem.PuppetisanITautomationsoftwareusedtopushconfigurationtoitsclients(puppetagents)usingcode. Puppetcodecandoavarietyoftasksfrominstallingnewsoftware,tocheckfilepermissions,orupdatinguseraccountsandlotsofothertasks ANSWER QUESTION 67
  • 69. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisSeLinux? 69 QUESTION SELinuxisanacronymforSecurity-enhancedLinux.ItisanaccesscontrolimplementationandsecurityfeaturefortheLinuxkernel.Itisdesignedtoprotecttheserveragainstmisconfigurationsand/orcompromiseddaemons.Itputlimitsandinstructsserverdaemonsorprogramswhatfilestheycanaccessandwhatactionstheycantakebydefiningasecuritypolicy. ANSWER QUESTION 68
  • 70. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Explainbrieflytheprocedureforre-installingGrubinLinux? 70 QUESTION 1)DownloadUbuntuInstallation/Livecd 2)BootfromUbuntuInstallation/Livecd-usb,burnedcdetc. 3)DuringbootselectTryUbuntu,Dontselectinstall! 4)MountyourLinuxrootpartition sudomount/dev/sda6/mnt(Assuming/dev/sda6istheLinuxrootpartition) 5)Install/reinstallgrub $sudogrub-install--root-directory=/mnt//dev/sda(where/dev/sdaisyourprimarydisk) Installationfinished.Noerrorreported. 6)Rebootyoursystem,removebootableCDandweshouldhavethebootmenureadywhenthesystemstarts. Note:Therewouldbeslightdifferencewhenusingwithotherdistros ANSWER QUESTION 69
  • 71. For the hottest LINUX jobs, please visit www.hirist.com hirist .com ExplainthedifferentScenariosinvolvedinTCP3wayhandshake? 71 QUESTION TheTCPthreewayhandshakeistheprocessforestablishingaTCPconnection.Wecanexplain3wayhandshakewithasimplescenariowhereweassumeaclientcomputeriscontactingaservertosenditsomeinformation. a)TheclientsendsapacketwiththeSYNbitsetandasequencenumberofN. b)TheserversendsapacketwithanACKnumberofN+1,theSYNbitsetandasequencenumberofX. c)TheclientsendsapacketwithanACKnumberofX+1andtheconnectionisestablished. d)Theclientsendsthedata. Thefirstthreestepsintheaboveprocessiscalledthethreewayhandshake. ANSWER QUESTION 70
  • 72. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisrDNSandexplainitsbenefitsintheLinuxDomainNameSystems? 72 QUESTION AtypicalDNSlookupisusedtodeterminewhichIPaddressisassociatedwithahostname,andthisiscalledForwardDNSlookup.AreverseDNSlookupisusedfortheopposite,todeterminewhichhostnameisassociatedwithanIPaddress.SometimesreverseDNSlookupsarerequiredfordiagnosticpurposes.Today,reverseDNSlookupsareusedmainlyforsecuritypurposestotraceahackerorspammer.Manymodernmailingsystemsusereversemappingtoprovidesimpleauthenticationusingduallookup:hostname-to-addressandaddress-to- hostname.TherDNS(reverseDNS)isimplementedusingaspecializedzonerecordforreverselookupscalledPTRrecord.PTRrecordsalwaysresolvetonames,neverIPaddresses. ANSWER QUESTION 71
  • 73. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhyisLVMrequired? 73 QUESTION LVMstandsforLogicalVolumeManager,toresizefilesystemssizeonlinewerequiredLVMpartitioninLinux.SizeofLVMpartitioncanbeextendedandreducedusingthelvextend&lvreducecommandsrespectively. ANSWER QUESTION 72
  • 74. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowtocheckMemorystatsandCPUstats? 74 QUESTION Usingfree&vmstatcommandwecandisplaythephysicalandvirtualmemorystatisticsrespectively.WiththehelpofsarcommandweseetheCPUutilization&otherstats. ANSWER QUESTION 73
  • 75. For the hottest LINUX jobs, please visit www.hirist.com hirist .com HowtoincreasethesizeofLVMpartition? 75 QUESTION BelowaretheLogicalSteps: -Usethelvextendcommand(lvextend-L+100M/dev/,inthisexampleweareextendingthesizeby100MB. -resize2fs/dev/ -checkthesizeofpartitionusingdf-hcommand ANSWER QUESTION 74
  • 76. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Howtocreatepartitionfromtherawdisk? 76 QUESTION Usingfdiskutilitywecancreatepartitionsfromtherawdisk.Belowarethestepstocreatepartitionfromtherawdsik: -fdisk/dev/hd*(IDE)or/dev/sd*(SCSI) -Typentocreateanewpartition -Aftercreatingpartition,typewcommandtowritethechangestothepartitiontable. ANSWER QUESTION 75
  • 77. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisloadaverageinalinux? 77 QUESTION LoadAverageisdefinedastheaveragesumofthenumberofprocesswaitingintherunqueueandnumberofprocesscurrentlyexecutingovertheperiodof1,5and15minutes.Usingthetopanduptimecommandwefindtheloadaverageofalinuxsever. ANSWER QUESTION 76
  • 78. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatistheroleofudevdaemon? 78 QUESTION Theudevdemonusedtocreateandremoveallthesedevicenodesorfilesin/dev/directory. ANSWER QUESTION 77
  • 79. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisRAID? 79 QUESTION RAID,standsforRedundantArrayofInexpensiveDisks.RAIDisamethodbywhichsamedataorinformationisspreadacrossseveraldisks,usingtechniquessuchasdiskstriping(RAIDLevel0),diskmirroring(RAIDLevel1), anddiskstripingwithparity(RAIDLevel5)toachieveredundancy,lowerlatency,increasedbandwidth,andmaximizedabilitytorecoverfromharddiskcrashes. ANSWER QUESTION 78
  • 80. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisCUPS?WhatisthelocationoflogfilesforCUPS? 80 QUESTION CUPSstandsfor"CommonUNIXPrintingSystem".CUPSisaopensourceprintingsystemdevelopedbyAppleInc. CUPSusestheInternetPrintingProtocol(IPP)toallowlocalprintingandprintsharing. ThelogfilesfortheCUPSprintingsystemarelocatedinthe/var/log/cups/directory. ANSWER QUESTION 79
  • 81. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisYUM? 81 QUESTION YUMstandsforYellowdogUpdater,ModifiedbecauseitisbasedonYUP,theYellowdogUpdater.WheredoesthenameYellowdogcomefrom?YellowDogisaversionofLinuxforthePowerArchitecturehardwareandisRPM- based,justlikeRedHatEnterpriseLinuxandFedora.YUP,andlaterYUM,werewrittenbytheLinuxcommunityasawaytomaintainanRPM-basedsystem. ANSWER QUESTION 80
  • 82. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Differentiaterelativepathfromabsolutepath. 82 QUESTION Relativepathreferstothepathrelativetothecurrentpath.Absolutepath,ontheotherhand,referstotheexactpathasreferencedfromtherootdirectory. ANSWER QUESTION 81
  • 83. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatispiping? 83 QUESTION Piping,representedbythepipecharacter|,isusedtocombinetwoormorecommandstogether.Theoutputofthefirstcommandservesasinputthenextcommand,andsoon. ANSWER QUESTION 82
  • 84. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisasuperuser? 84 QUESTION Asuperuserisaspecialtypeuserwhohasopenaccesstoallfilesandcommandsonasystem.Notethatthesuperusersloginisusuallyroot,andisprotectedbyaso-calledrootpassword. ANSWER QUESTION 83
  • 85. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatistheuseoftheteecommand? 85 QUESTION Theteecommanddoestwothings:oneistogetdatafromthestandardinputandsendittostandardoutput;thesecondisthatitredirectsacopyofthatinputdataintoafilethatwasspecified. ANSWER QUESTION 84
  • 86. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisparsing? 86 QUESTION Parsingistheprocessofbreakingupofacommandlineintowords.Thisismadepossiblebyusingdelimitersandspaces.Intheeventthattabsormultiplespacesarepartofthecommand,theseareeventuallyreplacedbyasinglespace. ANSWER QUESTION 85
  • 87. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatispid? 87 QUESTION PidisshortforProcessID.ItisusedprimarilytoidentifyeveryprocessthatrunsontheUNIXsystem,whetheritrunsontheforegroundorrunsatthebackground.Everypidisconsideredunique. ANSWER QUESTION 86
  • 88. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisldd? 88 QUESTION Listdynamicdependenciesprintsharedlibrarydependencies Eg:#vimnew.c #gccnew.conew #lddnew ANSWER QUESTION 87
  • 89. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhatisthecommandtouninstallprocessesinLinux? 89 QUESTION rpmesendmail -eremove ANSWER QUESTION 88
  • 90. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WhataretheLinuxbootfiles? 90 QUESTION 1./boot/grub/grub.conf:containsbootdiskparameters 2./etc/fstab:containsFilesystemswhichneedtomountatboottime 3./etc/initab:Containsdefaultrunlevel 4./etc/init.d/rc.d/rcN.d:Thisisadiritcontains ANSWER QUESTION 89
  • 91. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Differencebetweennfssoftandhardmountingpoints? 91 QUESTION Hardmountoption:Iftheclientfailstoaccesstheserver,thentheconnectionhangsandoncethesystemisupthenitwillagainaccesstheserver. Soft:Iftheclientfailedtoconnecttheserver,itimmediatelygivestheerrorreportandclosestheconnection. ANSWER QUESTION 90
  • 92. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisthestatuscode403,404representedinapacheserver? 92 QUESTION 403representforbiddenerror,meansifafilemissessomeselinuxsecuritycontext. 404representthatthereisacgiscriptmissingorwebpagesmissing. ANSWER QUESTION 91
  • 93. For the hottest LINUX jobs, please visit www.hirist.com hirist .com WHATISTHEMEANINGOFAIX 93 QUESTION AIX(AdvancedInteractiveeXecutive)isanopenoperatingsystemfromIBMwhichisbasedonaversionofUNIX. AIX/ESAwasdesignedforIBMsSystem/390orlargeserverhardwareplatform.AIX/6000isanoperatingsystemthatrunsonIBMsworkstationplatform,theRISCSystem/6000. ANSWER QUESTION 92
  • 94. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whoinventedunix? 94 QUESTION Unixwascreatedin1969byKenThompsonandDennisRitchieatBellLaboratories. ANSWER QUESTION 93
  • 95. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatisthecommandtomakeaprocesstorunintheforegroundfrombackground? 95 QUESTION Whentheprocessisrunning,presscontrol+Z.Nowatthecommandprompt,typebg ANSWER QUESTION 94
  • 96. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Iwanttoseehowmanyinterfaces(Ethernetcards)areworkingusingsinglecommand? 96 QUESTION Ifconfig ANSWER QUESTION 95
  • 97. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Afilewhichisnotdeletedbynormaluserandalsoroot(usingrm),forthattypeoffilehowwedeleteit? 97 QUESTION Usingchattrcommand,weneedtochangetheattributesandthenweremoveusingrmcommand. Eg:chattr-iIuexample rm-rfexample ANSWER QUESTION 96
  • 98. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatiswild-cardinterpretation? 98 QUESTION Whenacommandlinecontainswild-cardcharacterssuchas*or?,thesearereplacedbytheshellwithasortedlistoffileswhosepatternmatchestheinputcommand.Wild-cardcharactersareusedtosetupalistoffilesforprocessing,insteadofhavingitspecifiedoneatatime. ANSWER QUESTION 97
  • 99. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Whatdoesthiscommanddo?catfood1>kitty 99 QUESTION Itredirectstheoutputofcatfoodintothefilekitty;thecommandisthesameas: catfood>kitty ANSWER QUESTION 98
  • 100. For the hottest LINUX jobs, please visit www.hirist.com hirist .com What"neat"commandwilldo? 100 QUESTION NeatcommandprovidesGraphicalinterfacetochangenetworksettingsfornetworkdevices. ANSWER QUESTION 99
  • 101. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Isthereanyrelationbetweenmodprobe.conffileandnetworkdevices? 101 QUESTION Yes,thisfileassignsakernelmoduletoeachnetworkdevice. ForExample:- [root@localhost~]#cat/etc/modprobe.conf aliaseth0b44 Hereb44isthekernelmodulefornetworkdeviceeth0. WecanConfirmbyfollowingcommand(Thismoduleb44ispresentornot). [root@localhost~]#lsmod|grepb44 b44290050 ANSWER QUESTION 100
  • 102. For the hottest LINUX jobs, please visit www.hirist.com hirist .com Resources 102 https://www.udemy.com/blog/linux-interview-questions/ http://www.masteringinlinux.com/linux-questions/top-linux-interview-question- answer.html http://computernetworkingnotes.com/rhce-interview-questions/basic-linux- interview-questions-for-freshers.html http://www.tecmint.com/core-linux-interview-questions-and-answers/ http://www.linuxtechi.com/experience-linux-admin-interview-questions/ http://www.01world.in/p/linux.html http://linoxide.com/linux-how-to/linux-interview-questions-answers/ http://career.guru99.com/top-50-linux-interview-questions/ http://www.tecmint.com/useful-random-linux-interview-questions-and-answers/ http://certcollection.org/forum/topic/154299-linux-system-administration- interview-questions-and-answers/ http://linuxserverworld.com/linux-interview-questions-part-i/
  • 103. www.hirist.com TOP 100 INTERVIEW QUESTIONS & ANSWERS LINUX