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
Citation preview
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