Unix Beginers

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IntroductiontoUnix

FrankG.Fiamingo

LindaDeBula

LindaCondron

UniversityTechnologyServicesTheOhioStateUniversity

September23,1998


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1996-1998UniversityTechnologyServices,TheOhioStateUniversity,BakerSystemsEngineeringBuilding,1971NeilAvenue,Columbus,OH43210.

Allrightsreserved.Redistributionanduse,withorwithoutmodification,arepermittedprovidedthatthefollowingconditionsaremet:

1.Redistributionsmustretaintheabovecopyrightnotice,thislistofconditions,andthefollowingdisclaimer.2.NeitherthenameoftheUniversitynorthenamesofitscontributorsmaybeusedtoendorseorpromoteproductsorservicesderivedfromthisdocumentwithoutspecificpriorwrittenpermission.THISPUBLICATIONISPROVIDED"ASIS"WITHOUTWARRANTYOFANYKIND.THISPUBLICATIONMAYINCLUDETECHNICALINACCURACIESORTYPOGRAPHICALERRORS.

UNIXisaregisteredtrademarkofTheOpenGroup,AT&TisatrademarkofAmericanTelephoneandTelegraph,Inc.

Thispublicationisprovidedasiswithoutwarrantyofanykind.Thispublication

mayincludetechnicalinaccuraciesortypographicalerrors.

CopyrightandURLsrevisedSeptember1998

Theauthorsemailaddressesare:[email protected]@[email protected]

Thisdocumentcanbeobtainedvia:http://wks.uts.ohio-state.edu/unix_course/unix.htmlor

ftp://wks.uts.ohio-state.edu/unix_course/unix_book.ps

1998UniversityTechnologyServices,TheOhioStateUniversityIntroductiontoUnix


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TableofContents

1HistoryofUnix..............................................................................72UnixStructure...............................................................................9

2.1TheOperatingSystem..................................................................9

2.2TheFileSystem...........................................................................11

2.3UnixDirectories,FilesandInodes.............................................12

2.4UnixPrograms............................................................................13

3GettingStarted............................................................................14

3.1Loggingin....................................................................................14

3.1.1TerminalType.............................................................14

3.1.2Passwords................................................................

....15

3.1.3Exiting.........................................................................15

3.1.4Identity........................................................................16

3.2UnixCommandLineStructure.................................................16

3.3ControlKeys................................................................................17

3.4stty-terminalcontrol.................................................................17


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3.5GettingHelp................................................................................19

3.6DirectoryNavigationandControl.............................................20

3.6.1pwd-printworkingdirectory.....................................21

3.6.2cd-changedirectory...................................................21

3.6.3mkdir-makeadirectory.............................................22

3.6.4rmdir-removedirectory.............................................22

3.6.5ls-listdirectorycontents............................................23

3.7FileMaintenanceCommands....................................................25

3.7.1cp-copyafile.............................................................26

3.7.2mv-moveafile..........................................................26

3.7.3rm-removeafile........................................................27

3.7.4FilePermissions..........................................................27

3.7.5chmod-changefilepermissions.................................28

3.7.6chown-changeownership..........................................29

3.7.7chgrp-changegroup..................................................29

3.8DisplayCommands.....................................................................30

3.8.1echo-echoastatement...............................................30


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3.8.2cat-concatenateafile.................................................31

3.8.3more,less,andpg-pagethroughafile......................31

3.8.4head-displaythestartofafile...................................32

3.8.5tail-displaytheendofafile......................................32

4

SystemResources&Printing....................................................33

4.1SystemResources........................................................................33

4.1.1df-summarizediskblockandfileusage....................34

4.1.2du-reportdiskspaceinuse........................................34

4.1.3ps-showstatusofactiveprocesses............................35

4.1.4kill-terminateaprocess.............................................36

4.1.5who-listcurrentusers................................................37

4.1.6whereis-reportprogramlocations............................37

4.1.7which-reportthecommandfound.............................38

4.1.8hostname/uname-nameofmachine...........................38

4.1.9script-recordyourscreenI/O....................................38

4.1.10date-currentdateandtime.........................................40

4.2PrintCommands.........................................................................41


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4.2.1lp/lpr-submitaprintjob............................................41

4.2.2lpstat/lpq-checkthestatusofaprintjob...................42

4.2.3cancel/lprm-cancelaprintjob...................................42

4.2.4pr-preparefilesforprinting.......................................43

5Shells............................................................................................45

5.1Built-inCommands.....................................................................46

5.1.1Sh................................................................................46

5.1.2Csh..............................................................................47

5.2EnvironmentVariables..............................................................48

5.3TheBourneShell,sh...................................................................49

5.4TheCShell,csh...........................................................................50

5.5JobControl..................................................................................51

5.6History..........................................................................................52

5.7ChangingyourShell........................................................

...........546SpecialUnixFeatures........................................................

.........55

6.1FileDescriptors...........................................................................55

6.2FileRedirection...........................................................


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................55

6.2.1Csh..............................................................................56

6.2.2Sh................................................................................57

6.3OtherSpecialCommandSymbols.............................................58

6.4WildCards...................................................................................587

TextProcessing............................................................................59

7.1RegularExpressionSyntax..................................................

......59

7.2TextProcessingCommands.......................................................61

7.2.1grep.............................................................................61

7.2.2sed...............................................................................65



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7.2.3awk,nawk,gawk.........................................................67

8

OtherUsefulCommands............................................................70

8.1WorkingWithFiles....................................................................70

8.1.1cmp-comparefilecontents........................................71

8.1.2diff-differencesinfiles..............................................72

8.1.3cut-selectpartsofaline............................................73

8.1.4paste-mergefiles.......................................................74

8.1.5touch-createafile......................................................76

8.1.6wc-countwordsinafile............................................77

8.1.7ln-linktoanotherfile................................................78

8.1.8sort-sortfilecontents.................................................79

8.1.9tee-copycommandoutput.........................................82

8.1.10uniq-removeduplicatelines......................................84

8.1.11strings-findASCIIstrings.........................................85

8.1.12file-filetype...............................................................86

8.1.13tr-translatecharacters................................................86


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8.1.14find-findfiles............................................................89

8.2FileArchiving,CompressionandConversion.........................91

8.2.1FileCompression........................................................91

8.2.2tar-archivefiles.........................................................93

8.2.3uuencode/uudecode-encodeafile.............................94

8.2.4dd-blockcopyandconvert........................................95

8.2.5od-octaldumpofafile..............................................96

8.3RemoteConnections...................................................................98

8.3.1TELNETandFTP-remoteloginandfiletransferprotocols98

8.3.2finger-getinformationaboutusers..........................100

8.3.3Remotecommands....................................................101

9ShellProgramming...................................................................103

9.1ShellScripts...............................................................................103

9.2SettingParameterValues.........................................................103

9.3Quoting......................................................................................104

9.4Variables....................................................................................105

9.5ParameterSubstitution.....................................................


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.......107

9.6HereDocument..........................................................................109

9.7InteractiveInput.......................................................................110

9.7.1Sh..............................................................................110

9.7.2Csh............................................................................110

9.8Functions....................................................................................111

9.9ControlCommands...........................................................

........113

9.9.1Conditionalif............................................................113

9.9.1.1Sh........................................................................113

9.9.1.2Csh......................................................................114

9.9.2Conditionalswitchandcase......................................115

9.9.2.1Sh........................................................................115



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9.9.2.2Csh......................................................................116

9.9.3forandforeach..........................................................117

9.9.3.1Sh........................................................................117

9.9.3.2Csh......................................................................117

9.9.4while..........................................................................118

9.9.4.1Sh........................................................................118

9.9.4.2Csh......................................................................119

9.9.5until...........................................................................119

9.9.6test.............................................................................120

9.9.7CShellLogicalandRelationalOperators................122

10Editors........................................................................................123

10.1ConfiguringYourviSession....................................................124

10.2ConfiguringYouremacsSession.............................................125

10.3viQuickReferenceGuide........................................................126

10.4emacsQuickReferenceGuide..............................................12711UnixCommandSummary.......................................................128


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11.1UnixCommands........................................................................12812AShortUnixBibliography......................................................131

12.1HighlyRecommended...............................................................131

12.2AssortedOthers.........................................................................131



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CHAPTER1

HistoryofUnix

1965BellLaboratoriesjoinswithMITandGeneralElectricinthedevelopmenteffortforthenewoperatingsystem,Multics,whichwouldprovidemulti-user,multi-processor,andmulti-level(hierarchical)filesystem,amongitsmanyforward-lookingfeatures.

1969AT&TwasunhappywiththeprogressanddropsoutoftheMulticsproject.SomeoftheBellLabsprogrammerswhohadworkedonthisproject,KenThompson,DennisRitchie,RuddCanaday,andDougMcIlroydesignedandimplementedthefirstversionoftheUnixFileSystemonaPDP-7alongwithafewutilities.ItwasgiventhenameUNIXbyBrianKernighanasapunonMultics.

1970,Jan1timezeroforUNIX

1971ThesystemnowrunsonaPDP-11,with16Kbytesofmemory,including8Kbytesforuser

programsanda512Kbytedisk.ItsfirstrealuseisasatextprocessingtoolforthepatentdepartmentatBellLabs.Thatutilizationjustifiedfurtherresearchanddevelopmentbytheprogramminggroup.UNIXcaughtonamongprogrammersbecauseitwasdesignedwiththesefeatures:

programmersenvironmentsimpleuserinterfacesimpleutilitiesthatcanbecombinedtoperformpowerfulfunctionshierarchicalfilesystemsimpleinterfacetodevicesconsistentwithfileformat

multi-user,multi-processsystemarchitectureindependentandtransparenttotheuser.1973Unixisre-writtenmostlyinC,anewlanguagedevelopedbyDennisRitchie.Beingwritteninthishigh-levellanguagegreatlydecreasedtheeffortneededtoportittonewmachines.

1974ThompsonandRitchiepublishapaperintheCommunicationsoftheACMdescribingthenewUnixOS.ThisgeneratesenthusiasmintheAcademiccommunitywhichseesapotentiallygreatteachingtoolforstudyingprogrammingsystemsdevelopment.SinceAT&Tispreventedfrom

marketingtheproductduetothe1956ConsentDecreetheylicenseittoUniversitiesforeducationalpurposesandtocommercialentities.

1977Therearenowabout500Unixsitesworld-wide.



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HistoryofUnix

1980BSD4.1(BerkeleySoftwareDevelopment)1983SunOS,BSD4.2,SysV

1984Therearenowabout100,000Unixsitesrunningonmanydifferenthardwareplatforms,ofvastlydifferentcapabilities.

1988AT&TandSunMicrosystemsjointlydevelopSystemVRelease4(SVR4).ThiswouldlaterbedevelopedintoUnixWareandSolaris2.

1993NovellbuysUNIXfromAT&T1994Novellgivesthename"UNIX"toX/OPEN

1995SantaCruzOperationsbuysUnixWarefromNovell.SantaCruzOperationsandHewlett-Packardannouncethattheywilljointlydevelopa64-bitversionofUnix.

1996InternationalDataCorporationforecaststhatin1997therewillbe3millionUnixsystemsshippedworld-wide.



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TheOperatingSystem

CHAPTER2UnixStructure

2.1TheOperatingSystemUnixisalayeredoperatingsystem.TheinnermostlayeristhehardwarethatprovidestheservicesfortheOS.Theoperatingsystem,referredtoinUnixasthekernel,interactsdirectlywiththehardwareandprovidestheservicestotheuserprograms.Theseuserprogramsdontneedtoknowanythingaboutthehardware.Theyjustneedtoknowhowtointeractwiththekernelanditsuptothekerneltoprovidethedesiredservice.OneofthebigappealsofUnixtoprogrammershasbeenthatmostwellwrittenuserprogramsareindependentoftheunderlyinghardware,makingthemreadilyportabletonewsystems.

Userprogramsinteractwiththekernelthroughasetofstandardsystemcalls.Thesesystemcallsrequestservicestobeprovidedbythekernel.Suchserviceswouldincludeacces

singafile:openclose,read,write,link,orexecuteafile;startingorupdatingaccountingrecords;changingownershipofafileordirectory;changingtoanewdirectory;creating,suspending,orkillingaprocess;enablingaccesstohardwaredevices;andsettinglimitsonsystemresources.

Unixisamulti-user,multi-taskingoperatingsystem.Youcanhavemanyusersloggedintoasystemsimultaneously,eachrunningmanyprograms.Itsthekernelsjobtokeepeachprocessanduserseparateandtoregulateaccesstosystemhardware,includingcpu,memory,diskandotherI/O

devices.



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UnixStructure

FIGURE2.1UnixSystemStructure

HardwareKernelSystemCallsPrograms1998UniversityTechnologyServices,TheOhioStateUniversityIntroductiontoUnix


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TheFileSystem

2.2TheFileSystemTheUnixfilesystemlookslikeaninvertedtreestructure.Youstartwiththerootdirectory,denotedby/,atthetopandworkdownthroughsub-directoriesunderneathit.

FIGURE2.2UnixFileStructure

/

bindevetclibtmpusrhome

shdatecshttyacua0passwdgroupbinliblocalcondronfranklindadb

sourcemailbin

xntptraceroute



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UnixStructure

Eachnodeiseitherafileoradirectoryoffiles,wherethelattercancontainotherfilesanddirectories.Youspecifyafileordirectorybyitspathname,eitherthefull,orabsolute,pathnameortheonerelativetoalocation.Thefullpathnamestartswiththeroot,/,andfollowsthebranchesofthefilesystem,eachseparatedby/,untilyoureachthedesiredfile,e.g.:

/home/condron/source/xntp

Arelativepathnamespecifiesthepathrelativetoanother,usuallythecurrentworkingdirectorythatyouareat.Twospecialdirectoryentriesshouldbeintroducednow:

.thecurrentdirectory

..theparentofthecurrentdirectory

SoifImat/home/frankandwishtospecifythepathaboveinarelativefashionIcoulduse:../condron/source/xntp

ThisindicatesthatIshouldfirstgouponedirectorylevel,thencomedownthroughthecondrondirectory,followedbythesourcedirectoryandthentoxntp.

2.3UnixDirectories,FilesandInodesEverydirectoryandfileislistedinitsparentdirectory.Inthecaseoftherootdirectory,thatparentisitself.Adirectoryisafilethatcontainsatablelistingthefilescontainedwithinit,givingfilenamestotheinodenumbersinthelist.Aninodeisaspecialfiledesignedtobereadbythekerneltolearntheinformationabouteachfile.Itspecifiesthepermissionsonthefile,

ownership,dateofcreationandoflastaccessandchange,andthephysicallocationofthedatablocksonthediskcontainingthefile.

Thesystemdoesnotrequireanyparticularstructureforthedatainthefileitself.ThefilecanbeASCIIorbinaryoracombination,andmayrepresenttextdata,ashellscript,compiledobjectcodeforaprogram,directorytable,junk,oranythingyouwouldlike.

Theresnoheader,trailer,labelinformationorEOFcharacteraspartofthefile.



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UnixPrograms

2.4UnixProgramsAprogram,orcommand,interactswiththekerneltoprovidetheenvironmentandperformthefunctionscalledforbytheuser.Aprogramcanbe:anexecutableshellfile,knownasashellscript;abuilt-inshellcommand;orasourcecompiled,objectcodefile.

Theshellisacommandlineinterpreter.Theuserinteractswiththekernelthroughtheshell.YoucanwriteASCII(text)scriptstobeacteduponbyashell.

Systemprogramsareusuallybinary,havingbeencompiledfromCsourcecode.Thesearelocatedinplaceslike/bin,/usr/bin,/usr/local/bin,/usr/ucb,etc.TheyprovidethefunctionsthatyounormallythinkofwhenyouthinkofUnix.Someofthesearesh,csh,date,who,more,andtherearemanyothers.



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GettingStarted

CHAPTER3

GettingStarted

3.1LogginginAfterconnectingwithaUnixsystem,auserispromptedforaloginusername,thenapassword.Theloginusernameistheuser'suniquenameonthesystem.Thepasswordisachangeablecodeknownonlytotheuser.Attheloginprompt,theusershouldentertheusername;atthepasswordprompt,thecurrentpasswordshouldbetyped.

Note:Unixiscasesensitive.Therefore,theloginandpasswordshouldbetypedexactlyasissued;thelogin,atleast,willnormallybeinlowercase.

3.1.1TerminalTypeMostsystemsaresetupsotheuserisbydefaultpromptedforaterminaltype,whichshouldbesettomatchtheterminalinusebeforeproceeding.Mostcomputersworkifyouchoose"

vt100".UsersconnectingusingaSunworkstationmaywanttouse"sun";thoseusinganX-Terminalmaywanttouse"xterms"or"xterm".

TheterminaltypeindicatestotheUnixsystemhowtointeractwiththesessionjustopened.

Shouldyouneedtoresettheterminaltype,enterthecommand:

setenvTERM-ifusingtheC-shell(seeChapter4.)

(Onsomesystems,e.g.MAGNUS,itsalsonecessarytotype"unsetenvTERMCAP".)

-or

TERM=;exportTERM-ifusingtheBourneshell(seeChapter4.)

whereistheterminaltype,suchasvt100,thatyouwouldlikeset.



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Loggingin

3.1.2PasswordsWhenyouraccountisissued,youwillbegivenaninitialpassword.Itisimportantforsystemandpersonalsecuritythatthepasswordforyouraccountbechangedtosomethingofyourchoosing.Thecommandforchangingapasswordis"passwd".Youwillbeaskedbothforyouroldpasswordandtotypeyournewselectedpasswordtwice.Ifyoumistypeyouroldpasswordordonottypeyournewpasswordthesamewaytwice,thesystemwillindicatethatthepasswordhasnotbeenchanged.

Somesystemadministratorshaveinstalledprogramsthatcheckforappropriatenessofpassword(isitcrypticenoughforreasonablesystemsecurity).Apasswordchangemayberejectedbythisprogram.

Whenchoosingapassword,itisimportantthatitbesomethingthatcouldnotbeguessed--eitherbysomebodyunknowntoyoutryingtobreakin,orbyanacquaintancewhoknowsyou.Suggestionsfor

choosingandusingapasswordfollow:Don'tuseaword(orwords)inanylanguage

useapropername

useinformationthatcanbefoundinyourwallet

useinformationcommonlyknownaboutyou(carlicense,petname,etc)

usecontrolcharacters.Somesystemscan'thandlethem

writeyourpasswordanywhere

evergiveyourpasswordto*anybody*

Douseamixtureofcharactertypes(alphabetic,numeric,special)

useamixtureofuppercaseandlowercase

useatleast6characters

chooseapasswordyoucanremember

changeyourpasswordoften

makesurenobodyislookingoveryourshoulderwhenyouareenteringyourpassword

3.1.3Exiting^D-indicatesendofdatastream;canlogauseroff.Thelatterisdisabledonmanysystems^C-interruptlogout-leavethesystemexit-leavetheshell


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GettingStarted

3.1.4IdentityThesystemidentifiesyoubytheuserandgroupnumbers(useridandgroupid,respectively)assignedtoyoubyyoursystemadministrator.Youdontnormallyneedtoknowyouruseridorgroupidasthesystemtranslatesusernameuserid,andgroupnamegroupidautomatically.Youprobablyalreadyknowyourusername;itsthenameyoulogonwith.Thegroupnameisnotasobvious,andindeed,youmaybelongtomorethanonegroup.Yourprimarygroupistheoneassociatedwithyourusernameinthepassworddatabasefile,assetupbyyoursystemadministrator.Similarly,thereisagroupdatabasefilewherethesystemadministratorcanassignyourightstoadditionalgroupsonthesystem.

Intheexamplesbelow%isyourshellprompt;youdonttypethisin.

Youcandetermineyouruseridandthelistofgroupsyoubelongtowiththeidandgroups

commands.Onsomesystemsiddisplaysyouruserandprimarygroupinformation,e.g.:

%iduid=1101(frank)gid=10(staff)

onothersystemsitalsodisplaysinformationforanyadditionalgroupsyoubelongto:

%iduid=1101(frank)gid=10(staff)groups=10(staff),5(operator),14(sysadmin),110(uts)

Thegroupscommanddisplaysthegroupinformationforallthegroupsyoubelongto,e.g.:

%groupsstaffsysadminutsoperator

3.2UnixCommandLineStructureAcommandisaprogramthattellstheUnixsystemtodosomething.Ithastheform:command[options][arguments]

whereanargumentindicatesonwhatthecommandistoperformitsaction,usuallyafileorseriesoffiles.Anoptionmodifiesthecommand,changingthewayitperforms.Commandsarecasesensitive.commandandCommandarenotthesame.Optionsaregenerallyprecededbyahyphen(-),andformostcommands,morethanoneoptioncanbe

strungtogether,intheform:command-[option][option][option]


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e.g.:ls-alR

willperformalonglistonallfilesinthecurrentdirectoryandrecursivelyperformthelistthroughallsub-directories.Formostcommandsyoucanseparatetheoptions,precedingeachwithahyphen,e.g.:

command-option1-option2-option3



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ControlKeys

asin:

ls-a-l-RSomecommandshaveoptionsthatrequireparameters.Optionsrequiringparametersareusuallyspecifiedseparately,e.g.:

lpr-Pprinter3-#2filewillsend2copiesoffiletoprinter3.

Thesearethestandardconventionsforcommands.However,notallUnixcommandswillfollowthestandard.Somedontrequirethehyphenbeforeoptionsandsomewontletyougroupoptionstogether,i.e.theymayrequirethateachoptionbeprecededbyahyphenandseparatedbywhitespacefromotheroptionsandarguments.

Optionsandsyntaxforacommandarelistedinthemanpageforthecommand.

3.3ControlKeys

Controlkeysareusedtoperformspecialfunctionsonthecommandlineorwithinaneditor.YoutypethesebyholdingdowntheControlkeyandsomeotherkeysimultaneously.Thisisusuallyrepresentedas^Key.Control-Swouldbewrittenas^S.Withcontrolkeysupperandlowercasearethesame,so^Sisthesameas^s.Thisparticularexampleisastopsignalandtellstheterminaltostopacceptinginput.Itwillremainthatwayuntilyoutypeastartsignal,^Q.

Control-Uisnormallythe"line-kill"signalforyourterminal.Whentypediterasestheentireinput

line.

Inthevieditoryoucantypeacontrolkeyintoyourtextfilebyfirsttyping^Vfollowedbythecontrolcharacterdesired,sototype^Hintoadocumenttype^V^H.

3.4stty-terminalcontrolsttyreportsorsetsterminalcontroloptions.The"tty"isanabbreviationthatharksbacktothedaysofteletypewriters,whichwereassociatedwithtransmissionoftelegraphmessages,andwhichweremodelsforearlycomputerterminals.

Fornewusers,themostimportantuseofthesttycommandissettingtheerasefunctiontotheappropriatekeyontheirterminal.Forsystemsprogrammersorshellscriptwriters,thesttycommandprovidesaninvaluabletoolforconfiguringmanyaspectsofI/Ocontrolforagivendevice,includingthefollowing:

-eraseandline-killcharacters-datatransmissionspeed


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-paritycheckingondatatransmission-hardwareflowcontrol-newline(NL)versuscarriagereturnpluslinefeed(CR-LF)IntroductiontoUnix1998UniversityTechnologyServices,TheOhioStateUniversity


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GettingStarted

-interpretingtabcharacters-editedversusrawinput-mappingofuppercasetolowercaseThiscommandisverysystemspecific,soconsultthemanpagesforthedetailsofthesttycommandonyoursystem.Syntaxstty[options]Options(none)reporttheterminalsettingsall(or-a)reportonalloptionsechoeechoERASEasBS-space-BSdecsetmodessuitableforDigitalEquipmentCorporationoperatingsystems(whichdistinguishesbetweenERASEandBACKSPACE)(Notavailableonallsystems)killsettheLINE-KILLcharactererasesettheERASEcharacterintrsettheINTERRUPTcharacter

Examples

Youcandisplayandchangeyourterminalcontrolsettingswiththesttycommand.Todisplayall(-a)ofthecurrentlinesettings:%stty-aspeed38400baud,24rows,80columnsparenb-paroddcs7-cstopb-hupclcread-clocal-crtscts-ignbrkbrkintignpar-parmrk-inpckistrip-inlcr-igncricrnl-iuclcixon-ixany-ixoffimaxbelisigiextenicanon-xcaseechoechoeechok-echonl-noflsh-tostopechoctl-echoprtechokeopost-olcuconlcr-ocrnl-onocr-onlret-ofill-ofdelerasekillweraserprntflushlnextsuspintrquitstopeof^H^U^W^R^O^V^Z/^Y^C^\^S/^Q^D

Youcanchangesettingsusingstty,e.g.,tochangetheerasecharacterfrom^?(thedeletekey)to^H:%sttyerase^H

Thiswillsettheterminaloptionsforthecurrentsessiononly.Tohavethisdoneforyouautomaticallyeachtimeyoulogin,itcanbeinsertedintothe.loginor.profilefilethatwelllookatlater.



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GettingHelp

3.5GettingHelpTheUnixmanual,usuallycalledmanpages,isavailableon-linetoexplaintheusageoftheUnixsystemandcommands.Touseamanpage,typethecommand"man"atthesystempromptfollowedbythecommandforwhichyouneedinformation.

Syntax

man[options]command_name

CommonOptions-kkeywordlistcommandsynopsislineforallkeywordmatches-Mpathpathtomanpages-ashowallmatchingmanpages(SVR4)

Examples

Youcanusemantoprovideaonelinesynopsisofanycommandsthatcontainthekeywordthatyouwanttosearchonwiththe"-k"option,e.g.tosearchonthekeywordpassword,

type:%man-kpasswordpasswd(5)-passwordfilepasswd(1)-changepasswordinformation

Thenumberinparenthesesindicatesthesectionofthemanpageswherethesereferenceswerefound.Youcanthenaccessthemanpage(bydefaultitwillgiveyouthelowernumberedentry,butyoucanuseacommandlineoptiontospecifyadifferentone)with:

%manpasswdPASSWD(1)USERCOMMANDSPASSWD(1)

NAME

passwd-changepasswordinformationSYNOPSIS

passwd[-elogin_shell][username]DESCRIPTION

passwdchanges(orsets)auser'spassword.

passwdpromptstwiceforthenewpassword,withoutdisplaying

it.Thisistoallowforthepossibilityoftypingmistakes.

Onlytheuserandthesuper-usercanchangetheuser'spassword.OPTIONS

-eChangetheuser'sloginshell.

Hereweveparaphrasedandtruncatedtheoutputforspaceandcopyrightconcerns.



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GettingStarted

3.6DirectoryNavigationandControlTheUnixfilesystemissetuplikeatreebranchingoutfromtheroot.Thetherootdirectoryofthesystemissymbolizedbytheforwardslash(/).Systemanduserdirectoriesareorganizedundertheroot.TheuserdoesnothavearootdirectoryinUnix;usersgenerallylogintotheirownhomedirectory.Userscanthencreateotherdirectoriesundertheirhome.Thefollowingtablesummarizessomedirectorynavigationcommands.

TABLE3.1NavigationandDirectoryControlCommands

Command/SyntaxWhatitwilldocd[directory]changedirectoryls[options][directoryorfile]listdirectorycontentsorfilepermissionsmkdir[options]directorymakeadirectorypwdprintworking(current)directoryrmdir[options]directoryremoveadirectory

IfyourefamiliarwithDOSthefollowingtablecomparingsimilarcommandsmighth

elptoprovidetheproperreferenceframe.

TABLE3.2UnixvsDOSNavigationandDirectoryControlCommands

CommandUnixDOSlistdirectorycontentslsdirmakedirectorymkdirmd&mkdirchangedirectorycdcd&chdirdelete(remove)directoryrmdirrd&rmdirreturntousershomedirectorycdcd\locationinpath(presentworkingdirectory)

pwdcd



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DirectoryNavigationandControl

3.6.1pwd-printworkingdirectoryAtanytimeyoucandeterminewhereyouareinthefilesystemhierarchywiththepwd,printworkingdirectory,command,e.g.:

%pwd/home/frank/src

3.6.2cd-changedirectoryYoucanchangetoanewdirectorywiththecd,changedirectory,command.cdwillacceptbothabsoluteandrelativepathnames.

Syntax

cd[directory]

Examples

cd(alsochdirinsomeshells)changedirectory

cdchangestouser'shomedirectorycd/changesdirectorytothesystem'srootcd..goesuponedirectorylevelcd../..goesuptwodirectorylevelscd/full/path/name/from/rootchangesdirectorytoabsolutepathnamed(notetheleadingslash)cdpath/from/current/locationchangesdirectorytopathrelativetocurrentlocation(noleading

slash)cd~username/directorychangesdirectorytothenamedusername'sindicateddirectory(Note:the~isnotvalidintheBourneshell;seeChapter5.)



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GettingStarted

3.6.3mkdir-makeadirectoryYouextendyourhomehierarchybymakingsub-directoriesunderneathit.Thisisdonewiththemkdir,makedirectory,command.Again,youspecifyeitherthefullorrelativepathofthedirectory:

Syntax

mkdir[options]directory

CommonOptions-pcreatetheintermediate(parent)directories,asneeded-mmodeaccesspermissions(SVR4).(WelllookatmodeslaterinthisChapter).Examples

%mkdir/home/frank/data

or,ifyourpresentworkingdirectoryis/home/frankthefollowingwouldbeequivalent:%mkdirdata

3.6.4rmdir-removedirectoryAdirectoryneedstobeemptybeforeyoucanremoveit.Ifitsnot,youneedtoremovethefilesfirst.Also,youcantremoveadirectoryifitisyourpresentworkingdirectory;youmustfirstchangeoutofit.

Syntax

rmdirdirectory

Examples

Toremovetheemptydirectory/home/frank/datawhilein/home/frankuse:%rmdirdataor%rmdir/home/frank/data



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DirectoryNavigationandControl

3.6.5ls-listdirectorycontentsThecommandtolistyourdirectoriesandfilesisls.Withoptionsitcanprovideinformationaboutthesize,typeoffile,permissions,datesoffilecreation,changeandaccess.

Syntax

ls[options][argument]

CommonOptions

Whennoargumentisused,thelistingwillbeofthecurrentdirectory.Therearemanyveryusefuloptionsforthelscommand.Alistingofmanyofthemfollows.Whenusingthecommand,stringthedesiredoptionstogetherprecededby"-".

-alistsallfiles,includingthosebeginningwithadot(.).-dlistsonlynamesofdirectories,notthefilesinthedirectory-Findicatestypeofentrywithatrailingsymbol:directories/

sockets=symboliclinks@executables*-gdisplaysUnixgroupassignedtothefile,requiresthe-loption(BSDonly)-or-onanSVR4machine,e.g.Solaris,thisoptionhastheoppositeeffect-Lifthefileisasymboliclink,liststheinformationforthefileordirectorythelinkreferences,nottheinformationforthelinkitself-llonglisting:liststhemode,linkinformation,owner,size,lastmodification(time).Ifthefileisasymboliclink,anarrow(-->)precedesthepathnameofthelinked-tofile.

Themodefieldisgivenbythe-loptionandconsistsof10characters.Thefirstcharacterisoneofthefollowing:

CHARACTERIFENTRYISAddirectory-plainfilebblock-typespecialfilec

character-typespecialfile

l

symboliclinkssocket

Thenext9charactersarein3setsof3characterseach.Theyindicatethefileaccesspermissions:thefirst3charactersrefertothepermissionsfortheuser,thenextthreefortheusersintheUnixgroupassignedtothefile,andthelast3tothepermissionsforotherusersonthesystem.


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Designationsareasfollows:



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rreadpermissionwwritepermissionx

executepermission-nopermission

Thereareafewlesscommonlyusedpermissiondesignationsforspecialcircumstances.Theseareexplainedinthemanpageforls.

Examples

Tolistthefilesinadirectory:%lsdemofilesfranklindaTolistallfilesinadirectory,includingthehidden(dot)filestry:

%ls-a..cshrc.history.plan.rhostsfrank...emacs.login.profiledemofileslinda

Togetalonglisting:%ls-al

total24drwxr-sr-x5workshopacs512Jun711:12.drwxr-xr-x6rootsys512May2909:59..-rwxr-xr-x1workshopacs532May2015:31.cshrc-rw-------1workshopacs525May2021:29.emacs-rw-------1workshopacs622May2412:13.history-rwxr-xr-x1workshopacs238May1409:44.login-rw-r--r--1workshopacs273May2223:53.plan-rwxr-xr-x1workshopacs413May1409:36.profile

-rw-------1workshopacs49May2020:23.rhostsdrwx------3workshopacs512May2411:18demofilesdrwx------2workshopacs512May2110:48frankdrwx------3workshopacs512May2410:59linda



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FileMaintenanceCommands

3.7FileMaintenanceCommandsTocreate,copy,removeandchangepermissionsonfilesyoucanusethefollowingcommands.

TABLE3.3FileMaintenanceCommands

Command/SyntaxWhatitwilldochgrp[options]groupfilechangethegroupofthefilechmod[options]filechangefileordirectoryaccesspermissionschown[options]ownerfilechangetheownershipofafile;canonlybedonebythesuperusercp[options]file1file2copyfile1intofile2;file2shouldn'talreadyexist.Thiscommandcreatesoroverwritesfile2.mv[options]file1file2movefile1intofile2rm[options]fileremove(delete)afileordirectory(-rrecursivelydeletesthedirectoryanditscontents)(-ipromptsbeforeremovingfiles)

IfyourefamiliarwithDOSthefollowingtablecomparingsimilarcommandsmighthelptoprovide

theproperreferenceframe.TABLE3.4UnixvsDOSFileMaintenanceCommands

CommandUnixDOScopyfilecpcopymovefilemvmove(notsupportedonallversionsofDOS)renamefilemvrename&rendelete(remove)filermerase&deldisplayfiletoscreenentirefileonepageatatimecat

more,less,pgtypetype/p(notsupportedonallversionsofDOS)



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3.7.1cp-copyafileCopythecontentsofonefiletoanotherwiththecpcommand.

Syntax

cp[options]old_filenamenew_filename

CommonOptions-i-rinteractive(promptandwaitforconfirmationbeforeproceeding)recursivelycopyadirectoryExamples

%cpold_filenamenew_filename

Younowhavetwocopiesofthefile,eachwithidenticalcontents.Theyarecompletelyindependentofeachotherandyoucaneditandmodifyeitherasneeded.Theyeachhavetheirowninode,datablocks,anddirectorytableentries.

3.7.2mv-moveafileRenameafilewiththemovecommand,mv.

Syntax

mv[options]old_filenamenew_filename

CommonOptions-i-finteractive(promptandwaitforconfirmationbeforeproceeding)dontprompt,evenwhencopyingoveranexistingtargetfile(overrides-i)

Examples

%mvold_filenamenew_filename

Younowhaveafilecallednew_filenameandthefileold_filenameisgone.Actuallyallyouvedoneistoupdatethedirectorytableentrytogivethefileanewname.Thecontentsofthefileremainwheretheywere.



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3.7.3rm-removeafileRemoveafilewiththerm,remove,command.

Syntax

rm[options]filename

CommonOptions-iinteractive(promptandwaitforconfirmationbeforeproceeding)-rrecursivelyremoveadirectory,firstremovingthefilesandsubdirectoriesbeneathit-fdontpromptforconfirmation(overrides-i)

Examples

%rmold_filename

Alistingofthedirectorywillnowshowthatthefilenolongerexists.Actually,allyouvedoneistoremovethedirectorytableentryandmarktheinodeasunused.Thefilecontentsarestillonthedisk,

butthesystemnowhasnowayofidentifyingthosedatablockswithafilename.Thereisnocommandto"unremove"afilethathasbeenremovedinthisway.Forthisreasonmanynoviceusersaliastheirremovecommandtobe"rm-i",wherethe-ioptionpromptsthemtoansweryesornobeforethefileisremoved.Suchaliasesarenormallyplacedinthe.cshrcfilefortheCshell;seeChapter5)

3.7.4FilePermissionsEachfile,directory,andexecutablehaspermissionssetforwhocanread,write,and/orexecuteit.

Tofindthepermissionsassignedtoafile,thelscommandwiththe-loptionshouldbeused.Also,usingthe-goptionwith"ls-l"willhelpwhenitisnecessarytoknowthegroupforwhichthepermissionsareset(BSDonly).

Whenusingthe"ls-lg"commandonafile(ls-lonSysV),theoutputwillappearasfollows:

-rwxr-x---userunixgroupsizeMonthnnhh:mmfilename

Theareaabovedesignatedbylettersanddashes(-rwxr-x---)istheareashowingthefiletypeand

permissionsasdefinedinthepreviousSection.Therefore,apermissionstring,forexample,of-rwxr-x---allowstheuser(owner)ofthefiletoread,write,andexecuteit;thoseintheunixgroupofthefilecanreadandexecuteit;otherscannotaccessitatall.



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3.7.5chmod-changefilepermissionsThecommandtochangepermissionsonanitem(file,directory,etc)ischmod(changemode).Thesyntaxinvolvesusingthecommandwiththreedigits(representingtheuser(owner,u)permissions,thegroup(g)permissions,andother(o)user'spermissions)followedbytheargument(whichmaybeafilenameorlistoffilesanddirectories).Orbyusingsymbolicrepresentationforthepermissionsandwhotheyapplyto.

Eachofthepermissiontypesisrepresentedbyeitheranumericequivalent:

read=4,write=2,execute=1

orasingleletter:

read=r,write=w,execute=x

Apermissionof4orrwouldspecifyreadpermissions.Ifthepermissionsdesiredarereadandwrite,

the4(representingread)andthe2(representingwrite)areaddedtogethertomakeapermissionof6.Therefore,apermissionsettingof6wouldallowreadandwritepermissions.

Alternatively,youcouldusesymbolicnotationwhichusestheoneletterrepresentationforwhoandforthepermissionsandanoperator,wheretheoperatorcanbe:

+addpermissions-removepermissions=setpermissions

Sotosetreadandwritefortheownerwecoulduse"u=rw"insymbolicnotation.

Syntax

chmodnnn[argumentlist]numericmodechmod[who]op[perm][argumentlist]symbolicmode

wherennnarethethreenumbersrepresentinguser,group,andotherpermissions,whoisanyofu,g,o,ora(all)andpermisanyofr,w,x.Insymbolicnotationyoucanseparatepermissionspecificationsbycommas,asshownintheexamplebelow.

CommonOptions-fforce(noerrormessageisgeneratedifthechangeisunsuccessful)

-RrecursivelydescendthroughthedirectorystructureandchangethemodesExamplesIfthepermissiondesiredforfile1isuser:read,write,execute,group:read,execute,other:read,

execute,thecommandtousewouldbechmod755file1orchmodu=rwx,go=rxfile1


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Reminder:Whengivingpermissionstogroupandothertouseafile,itisnecessarytoallowatleastexecutepermissiontothedirectoriesforthepathinwhichthefileislocated.Theeasiestwaytodothisistobeinthedirectoryforwhichpermissionsneedtobegranted:

chmod711.orchmodu=rw,+x.orchmodu=rwx,go=x.

wherethedot(.)indicatesthisdirectory.

3.7.6chown-changeownershipOwnershipofafilecanbechangedwiththechowncommand.OnmostversionsofUnixthiscanonlybedonebythesuper-user,i.e.anormalusercantgiveawayownershipoftheirfiles.chownisusedasbelow,where#representstheshellpromptforthesuper-user:

Syntax

chown[options]user[:group]file(SVR4)chown[options]user[.group]file(BSD)

CommonOptions-Rrecursivelydescendthroughthedirectorystructure-fforce,anddontreportanyerrorsExamples

#chownnew_ownerfile

3.7.7chgrp-changegroupAnyonecanchangethegroupoffilestheyown,toanothergrouptheybelongto,withthechgrpcommand.

Syntax

chgrp[options]groupfile

CommonOptions-Rrecursivelydescendthroughthedirectorystructure-fforce,anddontreportanyerrorsExamples

%chgrpnew_groupfile

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GettingStarted

3.8DisplayCommandsThereareanumberofcommandsyoucanusetodisplayorviewafile.Someoftheseareeditorswhichwewilllookatlater.Herewewillillustratesomeofthecommandsnormallyusedtodisplayafile.

TABLE3.5DisplayCommands

Command/SyntaxWhatitwilldocat[options]fileconcatenate(list)afileecho[textstring]echothetextstringtostdouthead[-number]filedisplaythefirst10(ornumberof)linesofafilemore(orlessorpg)[options]filepagethroughatextfiletail[options]filedisplaythelastfewlines(orparts)ofafile

3.8.1echo-echoastatementTheechocommandisusedtorepeat,orecho,theargumentyougiveitbacktothestandardoutputdevice.Itnormallyendswithaline-feed,butyoucanspecifyanoptiontopreventthis.

Syntax

echo[string]

CommonOptions-ndontprint(BSD,shellbuilt-in)\cdontprint(SVR4)\0nwherenisthe8-bitASCIIcharactercode(SVR4)

\ttab(SVR4)\fform-feed(SVR4)\nnew-line(SVR4)

\vverticaltab(SVR4)Examples%echoHelloClassorecho"HelloClass"

Topreventthelinefeed:%echo-nHelloClassorecho"HelloClass\c"wherethestyletouseinthelastexampledependsontheechocommandinuse.The\xoptionsmustbewithinpairsofsingleordoublequotes,withorwithoutotherstringcharacters.



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GettingStarted

InternalControlsmoredisplays(onescreenatatime)thefilerequestedtoviewnextscreenortoviewonemorelineqtoquitviewingthefilehhelpbgobackuponescreenful/wordsearchforwordintheremainderofthefileSeethemanpageforadditionaloptionslesssimilartomore;seethemanpageforoptionspgtheSVR4equivalentofmore(page)

3.8.4head-displaythestartofafileheaddisplaysthehead,orstart,ofthefile.

Syntax

head[options]file

CommonOptions-nnumbernumberoflinestodisplay,countingfromthetopofthefile

-numbersameasaboveExamples

Bydefaultheaddisplaysthefirst10lines.Youcandisplaymorewiththe"-nnumber",or"-number"options,e.g.,todisplaythefirst40lines:%head-40filenameorhead-n40filename

3.8.5tail-displaytheendofafiletaildisplaysthetail,orend,ofthefile.

Syntax

tail[options]file

CommonOptions-numbernumberoflinestodisplay,countingfromthebottomofthefileExamples

Thedefaultistodisplaythelast10lines,butyoucanspecifydifferentlineorbytenumbers,oradifferentstartingpointwithinthefile.Todisplaythelast30linesofafileusethe-numberstyle:

%tail-30filename



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SystemResources

CHAPTER4SystemResources&Printing

4.1SystemResourcesCommandstoreportormanagesystemresources.

TABLE4.1SystemResourceCommands

Command/SyntaxWhatitwilldochsh(passwd-e/-s)usernamelogin_shellchangetheusersloginshell(oftenonlybythesuperuser)date[options]reportthecurrentdateandtimedf[options][resource]reportthesummaryofdiskblocksandinodesfreeandinusedu[options][directoryorfile]reportamountofdiskspaceinuse+hostname/unamedisplayorset(super-useronly)thenameofthecurrentmachinekill[options][-SIGNAL][pid#][%job]sendasignaltotheprocesswiththeprocessidnumber(pid#)orjobcontrolnumber(%n).Thedefaultsignalistokilltheprocess.man[options]commandshowthemanual(man)pageforacommandpasswd[options]setorchangeyourpassword

ps[options]showstatusofactiveprocessesscriptfilesaveseverythingthatappearsonthescreentofileuntilexitisexecutedstty[options]setordisplayterminalcontroloptionswhereis[options]commandreportthebinary,source,andmanpagelocationsforthecommandnamedwhichcommandreportsthepathtothecommandortheshellaliasinusewhoorwreportwhoisloggedinandwhatprocessesarerunning



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SystemResources&Printing

4.1.1df-summarizediskblockandfileusagedfisusedtoreportthenumberofdiskblocksandinodesusedandfreeforeachfilesystem.TheoutputformatandvalidoptionsareveryspecifictotheOSandprogramversioninuse.

Syntax

df[options][resource]

CommonOptions-llocalfilesystemsonly(SVR4)-kreportinkilobytes(SVR4)

Examples

{unixprompt1}dfFilesystemkbytesusedavailcapacityMountedon/dev/sd0a20895192240102%//dev/sd0h31905513129315585746%/usr/dev/sd1g63772634880922514561%/usr/local

/dev/sd1a2401111654895061177%

/home/guardianperi:/usr/local/backup

195257397655878075856%/usr/local/backupperi:/home/peri72688439118926300760%/home/periperi:/usr/spool/mail19238310811720641%

/var/spool/mailperi:/acs/peri/272393452160412993780%/acs/peri/2

4.1.2du-reportdiskspaceinusedureportstheamountofdiskspaceinuseforthefilesordirectoriesyouspecify.

Syntax

du[options][directoryorfile]

CommonOptions

-adisplaydiskusageforeachfile,notjustsubdirectories-sdisplayasummarytotalonly-kreportinkilobytes(SVR4)



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Examples

{unixprompt3}du1./.elm1

./Mail1

./News20./uc

86.{unixprompt4}du-auc7uc/unixgrep.txt5uc/editors.txt1uc/.emacs1uc/.exrc4uc/telnet.ftp1uc/uniq.tee.txt20uc

4.1.3ps-showstatusofactiveprocessespsisusedtoreportonprocessescurrentlyrunningonthesystem.TheoutputformatandvalidoptionsareveryspecifictotheOSandprogramversioninuse.

Syntax

ps[options]

CommonOptions

BSDSVR4

-a-eallprocesses,allusers-eenvironment/everything-gprocessgroupleadersaswell-l-llongformat-u-uuseruserorientedreport-x-eevenprocessesnotexecutedfromterminals-ffulllisting-wreportfirst132charactersperline

note--Becausethepscommandishighlysystem-specific,itisrecommendedthatyouconsultthemanpagesofyoursystemfordetailsofoptionsandinterpretationofpsoutput.



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Examples

{unixprompt5}ps

PIDTTSTATTIMECOMMAND15549p0IW0:00-tcsh(tcsh)15588p0IW0:00mannice15594p0IW0:00sh-cless/tmp/man1558815595p0IW0:00less/tmp/man1558815486p1S0:00-tcsh(tcsh)15599p1T0:00emacsunixgrep.txt15600p1R0:00ps

4.1.4kill-terminateaprocesskillsendsasignaltoaprocess,usuallytoterminateit.

Syntax

kill[-signal]process-id

CommonOptions-ldisplaystheavailablekillsignals:Examples

{unixprompt9}kill-l

HUPINTQUITILLTRAPIOTEMTFPEKILLBUSSEGVSYSPIPEALRMTERMURGSTOP

TSTPCONTCHLDTTINTTOUIOXCPUXFSZVTALRMPROFWINCHLOSTUSR1USR2

The-KILLsignal,alsospecifiedas-9(becauseitis9thontheabovelist),isthemostcommonly

usedkillsignal.Onceseen,itcantbeignoredbytheprogramwhereastheothersignalscan.

{unixprompt10}kill-915599

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SystemResources

4.1.5who-listcurrentuserswhoreportswhoisloggedinatthepresenttime.

Syntax

who[ami]

Examples

beautycondron>who

wmtellttyp1Apr2120:15(apple.acs.ohio-s)fbwalkttyp2Apr2123:21(worf.acs.ohio-st)stwangttyp3Apr2123:22(127.99.25.8)davidttyp4Apr2122:27(slip1-61.acs.ohi)tgardnerttyp5Apr2123:07(picard.acs.ohio-)awallacettyp6Apr2123:00(ts31-4.homenet.o)gtl27ttyp7Apr2123:24(data.acs.ohio-st)ccchangttyp8Apr2123:32(slip3-10.acs.ohi)condronttypcApr2123:38(lcondron-mac.acs)

dgildmanttypeApr2122:30(slip3-36.acs.ohi)fcbetzttyq2Apr2121:12(ts24-10.homenet.)

beautycondron>whoamibeauty!condronttypcApr2123:38(lcondron-mac.acs)

4.1.6whereis-reportprogramlocationswhereisreportsthefilenamesofsource,binary,andmanualpagefilesassociatedwithcommand(s).

Syntax

whereis[options]command(s)

CommonOptions-breportbinaryfilesonly-mreportmanualsectionsonly-sreportsourcefilesonly

Examples

brigadier:condron[69]>whereisMailMail:/usr/ucb/Mail/usr/lib/Mail.help/usr/lib/Mail.rc/usr/man/man1/Mail.1

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brigadier:condron[70]>whereis-bMailMail:/usr/ucb/Mail/usr/lib/Mail.help/usr/lib/Mail.rc

brigadier:condron[71]>whereis-mMailMail:/usr/man/man1/Mail.1

4.1.7which-reportthecommandfoundwhichwillreportthenameofthefilethatisbeexecutedwhenthecommandisinvoked.Thiswillbethefullpathnameorthealiasthatsfoundfirstinyourpath.

Syntax

whichcommand(s)

example-brigadier:condron[73]>whichMail/usr/ucb/Mail

4.1.8hostname/uname-nameofmachinehostname(uname-nonSysV)reportsthehostnameofthemachinetheuserisloggedinto,e.g.:brigadier:condron[91]>hostnamebrigadier

unamehasadditionaloptionstoprintinformationaboutsystemhardwaretypeandsoftwareversion.

4.1.9script-recordyourscreenI/Oscriptcreatesascriptofyoursessioninputandoutput.Usingthescriptcommand,youcancaptureallthedatatransmissionfromandtoyourterminalscreenuntilyouexitthesc

riptprogram.Thiscanbeusefulduringtheprogramming-and-debuggingprocess,todocumentthecombinationofthingsyouhavetried,ortogetaprintedcopyofitallforlaterperusal.

Syntax

script[-a][file]exit

CommonOptions-aappendtheoutputtofile

typescriptisthenameofthedefaultfileusedbyscript.

Youmustremembertotypeexittoendyourscriptsessionandcloseyourtypescriptfile.



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4.1.10date-currentdateandtimedatedisplaysthecurrentdataandtime.Asuperusercansetthedateandtime.

Syntax

date[options][+format]

CommonOptions-uuseUniversalTime(orGreenwichMeanTime)+formatspecifytheoutputformat%aweekdayabbreviation,SuntoSat%hmonthabbreviation,JantoDec%jdayofyear,001to366%n%t%ylast2digitsofyear,00to99%DMM/DD/YYdate%Hhour,00to23%Mminute,00to59%Ssecond,00to59%THH:MM:SStime

Examples

beautycondron>dateMonJun1009:01:05EDT1996

beautycondron>date-uMonJun1013:01:33GMT1996

beautycondron>date+%a%t%DMon06/10/96

beautycondron>date'+%y:%j'

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PrintCommands

4.2.4pr-preparefilesforprintingprprintsheaderandtrailerinformationsurroundingtheformattedfile.Youcanspecifythenumberofpages,linesperpage,columns,linespacing,pagewidth,etc.toprint,alongwithheaderandtrailerinformationandhowtotreatcharacters.

Syntaxpr[options]fileCommonOptions+page_numberstartprintingwithpagepage_numberoftheformattedinputfile-columnnumberofcolumns-amodify-columnoptiontofillcolumnsinround-robinorder-ddoublespacing-e[char][gap]tabspacing-hheader_stringheaderforeachpage-llineslinesperpage-tdontprinttheheaderandtraileroneachpage-wwidthwidthofpage

Examples

ThefilecontainingthelistofP.G.WodehousesLordEmsworthbookscouldbeprinted,at14linesperpage(including5headerand5(empty)trailerlines)below,wherethe-eoptionspecifiestheconversionstyle:

%pr-l14-e42wodehouse

Apr2911:111996wodehouse_emsworth_booksPage1

SomethingFresh[1915]UncleDynamite[1948]LeaveittoPsmith[1923]PigsHaveWings[1952]SummerLightning[1929]CocktailTime[1958]HeavyWeather[1933]ServicewithaSmile[1961]



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Shells

5.2EnvironmentVariablesEnvironmentalvariablesareusedtoprovideinformationtotheprogramsyouuse.Youcanhavebothglobalenvironmentandlocalshellvariables.Globalenvironmentvariablesaresetbyyourloginshellandnewprogramsandshellsinherittheenvironmentoftheirparentshell.Localshellvariablesareusedonlybythatshellandarenotpassedontootherprocesses.Achildprocesscannotpassavariablebacktoitsparentprocess.

Thecurrentenvironmentvariablesaredisplayedwiththe"env"or"printenv"commands.Somecommononesare:

DISPLAYThegraphicaldisplaytouse,e.g.nyssa:0.0EDITORThepathtoyourdefaulteditor,e.g./usr/bin/viGROUPYourlogingroup,e.g.staff

HOMEPathtoyourhomedirectory,e.g./home/frankHOSTThehostnameofyoursystem,e.g.nyssaIFSInternalfieldseparators,usuallyanywhitespace(defaultstotab,spaceand)LOGNAMEThenameyouloginwith,e.g.frankPATHPathstobesearchedforcommands,e.g./usr/bin:/usr/ucb:/usr/local/binPS1Theprimarypromptstring,Bourneshellonly(defaultsto$)

PS2Thesecondarypromptstring,Bourneshellonly(defaultsto>)SHELLTheloginshellyoureusing,e.g./usr/bin/cshTERMYourterminaltype,e.g.xtermUSERYourusername,e.g.frankManyenvironmentvariableswillbesetautomaticallywhenyoulogin.Youcanmodifythemordefineotherswithentriesinyourstartupfilesoratanytimewithintheshell.SomevariablesyoumightwanttochangearePATHandDISPLAY.ThePATHvariablespecifiesthedirectoriestobeautomatically

searchedforthecommandyouspecify.Examplesofthisareintheshellstartupscriptsbelow.YousetaglobalenvironmentvariablewithacommandsimilartothefollowingfortheCshell:

%setenvNAMEvalueandforBourneshell:

$NAME=value;exportNAMEYoucanlistyourglobalenvironmentalvariableswiththeenvorprintenvcomman


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ds.Youunsetthemwiththeunsetenv(Cshell)orunset(Bourneshell)commands.

TosetalocalshellvariableusethesetcommandwiththesyntaxbelowforCshell.Withoutoptionssetdisplaysallthelocalvariables.

%setname=valueFortheBourneshellsetthevariablewiththesyntax:

$name=value

Thecurrentvalueofthevariableisaccessedviathe"$name",or"${name}",notation.



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Shells

5.4TheCShell,cshCshusesthestartupfiles.cshrcand.login.Someversionsuseasystem-widestartupfile,e.g./etc/csh.login.Your.loginfileissourced(executed)onlywhenyoulogin.Your.cshrcfileissourcedeverytimeyoustartacsh,includingwhenyoulogin.Ithasmanysimilarfeaturesto.profile,butadifferentstyleofdoingthings.Hereweusethesetorsetenvcommandstoinitializeavariable,wheresetisusedforthisshellandsetenvforthisandanysubshells.Theenvironmentvariables:USER,TERM,andPATH,areautomaticallyimportedtoandexportedfromtheuser,term,andpathvariablesofthecsh.Sosetenvdoesntneedtobedoneforthese.TheCshellusesthesymbol,~,toindicatetheusershomedirectoryinapath,asin~/.cshrc,ortospecifyanotheruserslogindirectory,asin~username/.cshrc.

PredefinedvariablesusedbytheCshellinclude:

argvThelistofargumentsofthecurrentshellcwdThecurrentworkingdirectoryhistorySetsthesizeofthehistorylisttosavehomeThehomedirectoryoftheuser;startswith$HOMEignoreeofWhensetignoreEOF(^D)fromterminalsnoclobberWhensetpreventoutputredirectionfromoverwritingexistingfilesnoglob

WhensetpreventfilenameexpansionwithwildcardpatternmatchingpathThecommandsearchpath;startswith$PATHpromptSetthecommandlineprompt(defaultis%)savehistnumberoflinestosaveinthehistorylisttosaveinthe.historyfileshellThefullpathnameofthecurrentshell;startswith$SHELLstatusTheexitstatusofthelastcommand(0=normalexit,1=failedcommand)term

Yourterminaltype,startswith$TERMuserYourusername,startswith$USERAsimple.cshrccouldbe:setpath=(/usr/bin/usr/ucb/usr/local/bin~/bin.)#setthepathsetprompt="{hostnamewhoami!}"#settheprimaryprompt;defaultis"%"setnoclobber#dontredirectoutputtoexistingfilessetignoreeof#ignoreEOF(^D)forthisshellsethistory=100savehist=50#keepahistorylistandsaveitbetweenlogins#aliasesaliashhistory#aliashto"history"


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aliasls"/usr/bin/ls-sbF"#aliaslsto"ls-sbF"aliasllls-al#aliasllto"ls-sbFal"(combiningtheseoptionswiththosefor"ls"above)aliascdcd\!*;pwd#aliascdsothatitprintsthecurrentworkingdirectoryafterthechangeumask077



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JobControl

Somenewfeaturesherethatwedidntseein.profilearenoclobber,ignoreeof,andhistory.Noclobberindicatesthatoutputwillnotberedirectedtoexistingfiles,whileignoreeofspecifiesthatEOF(^D)willnotcausetheloginshelltoexitandlogyouoffthesystem.

Withthehistoryfeatureyoucanrecallpreviouslyexecutedcommandsandre-executethem,withchangesifdesired.

Analiasallowsyoutousethespecifiedaliasnameinsteadofthefullcommand.Inthe"ls"exampleabove,typing"ls"willresultin"/usr/bin/ls-sbF"beingexecuted.Youcantellwhich"ls"commandisinyourpathwiththebuilt-inwhichcommand,i.e.:

whichlsls:aliasedto/usr/bin/ls-sbFAsimple.logincouldbe:#.loginsttyerase^H#setControl-Htobetheerasekey

setnoglob#preventwildcardpatternmatchingevaltset-Q-s-m:?xterm#promptfortheterminaltype,assume"xterm"unsetnoglob#re-enablewildcardpatternmatching

Settingandunsettingnoglobaroundtsetpreventsitfrombeingconfusedbyanycshfilenamewildcard

patternmatchingorexpansion.Shouldyoumakeanychangestoyourstartupfilesyoucaninitiatethechangebysourcingthechangedfile.Forcshyoudothiswiththebuilt-insourcecommand,i.e.:

source.cshrcForfurtherinformationaboutcshtype"mancsh"attheshellprompt.

5.5JobControlWiththeCshell,csh,andmanynewershellsincludingsomenewerBourneshells,youcanputjobsintothebackgroundatanytimebyappending"&"tothecommand,aswithsh.Aftersubmittingacommandyoucanalsodothisbytyping^Z(Control-Z)tosuspendthejobandthen"bg"toputitintothebackground.Tobringitbacktotheforegroundtype"fg".

Youcanhavemanyjobsrunninginthebackground.Whentheyareinthebackgroun

dtheyarenolongerconnectedtothekeyboardforinput,buttheymaystilldisplayoutputtotheterminal,interspersingwithwhateverelseistypedordisplayedbyyourcurrentjob.YoumaywanttoredirectI/Otoorfromfilesforthejobyouintendtobackground.Yourkeyboardisconnectedonlytothecurrent,foreground,job.

Thebuilt-injobscommandallowsyoutolistyourbackgroundjobs.Youcanuset


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5.7ChangingyourShellTochangeyourshellyoucanusuallyusethe"chsh"or"passwd-e"commands.Theoptionflag,here-e,mayvaryfromsystemtosystem(-sonBSDbasedsystems),socheckthemanpageonyoursystemforproperusage.Sometimesthisfeatureisdisabled.IfyoucantchangeyourshellcheckwithyourSystemAdministrator.

Thenewshellmustbethefullpathnameforavalidshellonthesystem.Whichshellsareavailabletoyouwillvaryfromsystemtosystem.Thefullpathnameofashellmayalsovary.Normally,though,theBourneandCshellsarestandard,andavailableas:

/bin/sh

/bin/cshSomesystemswillalsohavetheKornshellstandard,normallyas:

/bin/ksh

Someshellsthatarequitepopular,butnotnormallydistributedbytheOSvendorsarebashandtcsh.Thesemightbeplacedin/binoralocallydefineddirectory,e.g./usr/local/binor/opt/local/bin.ShouldyouchooseashellnotstandardtotheOSmakesurethatthisshell,andallloginshellsavailableonthesystem,arelistedinthefile/etc/shells.Ifthisfileexistsandyourshellisnotlistedinthisfilethefiletransferprotocoldaemon,ftpd,willnotletyouconnecttothismachine.Ifthisfiledoesnotexistonlyaccountswith"standard"shellsareallowedtoconnectviaftp.

Youcanalwaystryoutashellbeforeyousetitasyourdefaultshell.Todoth

isjusttypeintheshellnameasyouwouldanyothercommand.



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6.2.2Sh2>filedirectstderrtofile>file2>&1directbothstdoutandstderrtofile>>file2>&1appendbothstdoutandstderrtofile2>&1|commandpipestdoutandstderrtocommandToredirectstdoutandstderrtotwoseparatefilesyoucando:

$command1>out_file2>err_file

or,sincetheredirectiondefaultstostdout:

$command>out_file2>err_file

WiththeBourneshellyoucanspecifyotherfiledescriptors(3through9)andredirectoutputthroughthem.Thisisdonewiththeform:

n>&mredirectfiledescriptorntofiledescriptorm

Weusedtheabovetosendstderr(2)tothesameplaceasstdout(1),2>&1,whenwewantedtohave

errormessagesandnormalmessagestogotofileinsteadoftheterminal.Ifwewantedonlytheerrormessagestogotothefilewecoulddothisbyusingaplaceholderfiledescriptor,3.Wellfirstredirect3to2,thenredirect2to1,andfinally,wellredirect1to3:

$(command3>&22>&11>&3)>file

Thissendsstderrto3thento1,andstdoutto3,whichisredirectedto2.So,ineffect,wevereversedfiledescriptors1and2fromtheirnormalmeaning.Wemightusethisinthefollowingexample:

$(catfile3>&22>&11>&3)>errfile

Soiffileisreadtheinformationisdiscardedfromthecommandoutput,butiffilecantbereadtheerrormessageisputinerrfileforyourlateruse.

Youcanclosefiledescriptorswhenyouredonewiththem:

m&-closesstdout



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6.3OtherSpecialCommandSymbolsInadditiontofileredirectionsymbolsthereareanumberofotherspecialsymbolsyoucanuseonacommandline.Theseinclude:

;commandseparator&runthecommandinthebackground&&runthecommandfollowingthisonlyifthepreviouscommandcompletessuccessfully,e.g.:grepstringfile&&catfile||runthecommandfollowingonlyifthepreviouscommanddidnotcompletesuccessfully,e.g.:grepstringfile||echo"Stringnotfound."()thecommandswithintheparenthesesareexecutedinasubshell.Theoutputofthesubshellcanbemanipulatedasabove.literalquotationmarks.Dontallowanyspecialmeaningtoanycharacterswithinthesequotations.\escapethefollowingcharacter(takeitliterally)""regularquotationmarks.Allowvariableandcommandsubstitutionwiththesesquotations(doesnotdisable$and\withinthestring).commandtaketheoutputofthiscommandandsubstituteitasanargument(s)onthe

commandline#everythingfollowinguntilisacomment

The\charactercanalsobeusedtoescapethecharactersothatyoucancontinuealongcommandonmorethanonephysicallineoftext.

6.4WildCardsTheshellandsometextprocessingprogramswillallowmeta-characters,orwildcards,andreplacethemwithpatternmatches.Forfilenamesthesemeta-charactersandtheirusesare:

?matchanysinglecharacterattheindicatedposition*matchanystringofzeroormorecharacters[abc...]matchanyoftheenclosedcharacters[a-e]matchanycharactersintherangea,b,c,d,e[!def]matchanycharactersnotoneoftheenclosedcharacters,shonly{abc,bcd,cde}matchanysetofcharactersseparatedbycomma(,)(nospaces),cshonly~homedirectoryofthecurrentuser,cshonly~userhomedirectoryofthespecifieduser,cshonly



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Thisexamplewillsearchforanyinstancesoftfollowedbyzeroormoreoccurrencesofe:{unixprompt13}grep'te*'num.list115fifteen214fourteen313thirteen412twelve610ten88eight133three142two

Thisexamplewillsearchforanyinstancesoftfollowedbyoneormoreoccurrencesofe:

{unixprompt14}grep'tee*'num.list

115fifteen

214fourteen

313thirteen610ten

Wecanalsotakeourinputfromaprogram,ratherthanafile.Herewereportonanylinesoutputbythewhoprogramthatbeginwiththeletterl.{unixprompt15}who|grep'^l'lcondronttyp0Dec102:41(lcondron-pc.acs.)



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cialmeaning.



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7.2.3awk,nawk,gawkawkisapatternscanningandprocessinglanguage.Itsnamecomesfromthelastinitialsofthethreeauthors:Alfred.V.Aho,Brian.W.Kernighan,andPeter.J.Weinberger.nawkisnewawk,anewerversionoftheprogram,andgawkisgnuawk,fromtheFreeSoftwareFoundation.Eachversionisalittledifferent.Herewellconfineourselvestosimpleexampleswhichshouldbethesameforallversions.OnsomeOSsawkisreallynawk.

awksearchesitsinputforpatternsandperformsthespecifiedoperationoneachline,orfieldsoftheline,thatcontainthosepatterns.Youcanspecifythepatternmatchingstatementsforawkeitheronthecommandline,orbyputtingtheminafileandusingthe-fprogram_fileoption.

Syntax

awkprogram[file]

whereprogramiscomposedofoneormore:

pattern{action}

fields.Eachinputlineischeckedforapatternmatchwiththeindicatedactionbeingtakenonamatch.Thiscontinuesthroughthefullsequenceofpatterns,thenthenextlineofinputischecked.

Inputisdividedintorecordsandfields.Thedefaultrecordseparatoris,andthevariableNRkeepstherecordcount.Thedefaultfieldseparatoriswhitespace,spacesand

tabs,andthevariableNFkeepsthefieldcount.Inputfield,FS,andrecord,RS,separatorscanbesetatanytimetomatchanysinglecharacter.Outputfield,OFS,andrecord,ORS,separatorscanalsobechangedtoanysinglecharacter,asdesired.$n,wherenisaninteger,isusedtorepresentthenthfieldoftheinputrecord,while$0representstheentireinputrecord.

BEGINandENDarespecialpatternsmatchingthebeginningofinput,beforethefirstfieldisread,andtheendofinput,afterthelastfieldisread,respectively.

Printingisallowedthroughtheprint,andformattedprint,printf,statements.

Patternsmayberegularexpressions,arithmeticrelationalexpressions,string-valuedexpressions,andbooleancombinationsofanyofthese.Forthelatterthepatternscanbecombinedwiththebooleanoperatorsbelow,usingparenthesestodefinethecombination:

||or&&and


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!not

Commaseparatedpatternsdefinetherangeforwhichthepatternisapplicable,e.g.:/first/,/last/

selectsalllinesstartingwiththeonecontainingfirst,andcontinuinginclusively,throughtheonecontaininglast.



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Toselectlines15through20usethepatternrange:NR==15,NR==20Regularexpressionsmustbeenclosedwithslashes(/)andmeta-characterscanbeescapedwiththebackslash(\).Regularexpressionscanbegroupedwiththeoperators:

|or,toseparatealternatives+oneormore?zeroorone

Aregularexpressionmatchcanbeeitherof:~containstheexpression!~doesnotcontaintheexpression

Sotheprogram:$1~/[Ff]rank/

istrueifthefirstfield,$1,contains"Frank"or"frank"anywherewithinthefield.Tomatchafieldidenticalto"Frank"or"frank"use:

$1~/^[Ff]rank$/Relationalexpressionsareallowedusingtherelationaloperators:greaterthan

Offhandyoudontknowifvariablesarestringsornumbers.Ifneitheroperandisknowntobenumeric,thanstringcomparisonsareperformed.Otherwise,anumericcomparison

isdone.Intheabsenceofanyinformationtothecontrary,astringcomparisonisdone,sothat:

$1>$2

willcomparethestringvalues.Toensureanumericalcomparisondosomethingsimilarto:($1+0)>$2

Themathematicalfunctions:exp,logandsqrtarebuilt-in.

1998UniversityTechnologyServices,TheOhioStateUniversityIntroductiontoU

nix


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Someotherbuilt-infunctionsinclude:

index(s,t)returnsthepositionofstringswheretfirstoccurs,or0ifitdoesntlength(s)returnsthelengthofstringssubstr(s,m,n)returnsthen-charactersubstringofs,beginningatpositionm

Arraysaredeclaredautomaticallywhentheyareused,e.g.:arr[i]=$1

assignsthefirstfieldofthecurrentinputrecordtotheithelementofthearray.

Flowcontrolstatementsusingif-else,while,andforareallowedwithCtypesyntax:

for(i=1;i


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OtherUsefulCommands

CHAPTER8OtherUsefulCommands

8.1WorkingWithFilesThissectionwilldescribeanumberofcommandsthatyoumightfindusefulinexaminingandmanipulatingthecontentsofyourfiles.

TABLE8.1Fileutilities

Command/SyntaxWhatitwilldocmp[options]file1file2comparetwofilesandlistwheredifferencesoccur(textorbinaryfiles)cut[options][file(s)]cutspecifiedfield(s)/character(s)fromlinesinfile(s)diff[options]file1file2comparethetwofilesanddisplaythedifferences(textfilesonly)file[options]fileclassifythefiletypefinddirectory[options][actions]findfilesmatchingatypeorpatternln[options]source_filetargetlinkthesource_filetothetargetpaste[options]filepastefield(s)ontothelinesinfile

sort[options]filesortthelinesofthefileaccordingtotheoptionschosenstrings[options]filereportanysequenceof4ormoreprintablecharactersendinginor.UsuallyusedtosearchbinaryfilesforASCIIstrings.tee[options]filecopystdouttooneormorefilestouch[options][date]filecreateanemptyfile,orupdatetheaccesstimeofanexistingfiletr[options]string1string2translatethecharactersinstring1fromstdinintothoseinstring2instdoutuniq[options]fileremoverepeatedlinesinafilewc[options][file(s)]displayword(orcharacterorline)countforfile(s)


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WorkingWithFiles

8.1.1cmp-comparefilecontentsThecmpcommandcomparestwofiles,and(withoutoptions)reportsthelocationofthefirstdifferencebetweenthem.ItcandealwithbothbinaryandASCIIfilecomparisons.Itdoesabyte-by-bytecomparison.

Syntax

cmp[options]file1file2[skip1][skip2]Theskipnumbersarethenumberofbytestoskipineachfilebeforestartingthecomparison.

CommonOptions-lreportoneachdifference-sreportexitstatusonly,notbytedifferences

Examples

Giventhefilesmon.logins:andtues.logins:

ageorgeageorgebsmithcbettscbettsjchenjchenjdoejmarschjmarschlkereslkeresmschmidtproysphillipsphillipwyeppwyepp

Thecomparisonofthetwofilesyields:

%cmpmon.loginstues.logins

mon.loginstues.loginsdiffer:char9,line2

Thedefaultittoreportonlythefirstdifferencefound.

Thiscommandisusefulindeterminingwhichversionofafileshouldbekeptwhenthereismorethanoneversion.



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Examples

Giventhefileusers:

jdoeJohnDoe4/15/96

lsmithLauraSmith3/12/96

pchenPaulChen1/5/96

jhsuJakeHsu4/17/96

sphilipSuePhillip4/2/96

andthefilephone:

JohnDoe555-6634

LauraSmith555-3382

PaulChen555-0987

JakeHsu555-1235

SuePhillip555-7623

thepastecommandcanbeusedinconjunctionwiththecutcommandtocreateanewfile,listing,thatincludestheusername,realname,lastlogin,andphonenumberofalltheusers.First,extractthephonenumbersintoatemporaryfile,temp.file:%cut-f2phone>temp.file555-6634555-3382

555-0987555-1235555-7623

Theresultcanthenbepastedtotheendofeachlineinusersanddirectedtothenewfile,listing:%pasteuserstemp.file>listingjdoeJohnDoe4/15/96237-6634lsmithLauraSmith3/12/96878-3382pchenPaulChen1/5/96888-0987jhsuJakeHsu4/17/96545-1235sphilipSuePhillip4/2/96656-7623

Thiscouldalsohavebeendoneononelinewithoutthetemporaryfileas:%cut-f2phone|pasteusers->listing

withthesameresults.Inthiscasethehyphen(-)isactingasaplaceholderforaninputfield(namely,theoutputofthecutcommand).



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OtherUsefulCommands

8.1.7ln-linktoanotherfileThelncommandcreatesa"link"oranadditionalwaytoaccess(orgivesanadditionalnameto)anotherfile.

Syntax

ln[options]source[target]Ifnotspecifiedtargetdefaultstoafileofthesamenameinthepresentworkingdirectory.

CommonOptions-fforcealinkregardlessoftargetpermissions;dontreporterrors(SVR4only)-smakeasymboliclink

Examples

Asymboliclinkisusedtocreateanewpathtoanotherfileordirectory.Ifagroupofusers,forexample,isaccustomedtousingacommandcalledchkmag,butthecommandhasbeenrewrittenand

isnowcalledchkit,creatingasymboliclinksotheuserswillautomaticallyexecutechkitwhentheyenterthecommandchkmagwilleasetransitiontothenewcommand.

Asymboliclinkwouldbedoneinthefollowingway:%ln-schkitchkmagThelonglistingforthesetwofilesisnowasfollows:

16-rwxr-x---1lindadbacs15927Apr2304:10chkit1lrwxrwxrwx1lindadbacs5Apr2304:11chkmag->chkit

Notethatwhilethepermissionsforchkmagareopentoall,sinceitislinkedt

ochkit,thepermissions,groupandownercharacteristicsforchkitwillbeenforcedwhenchkmagisrun.

Withasymboliclink,thelinkcanexistwithoutthefileordirectoryitislinkedtoexistingfirst.Ahardlinkcanonlybedonetoanotherfileonthesamefilesystem,butnottoadirectory(exceptbythesuperuser).Ahardlinkcreatesanewdirectoryentrypointingtothesameinodeastheoriginalfile.Thefilelinkedtomustexistbeforethehardlinkcanbecreated.Thefilewillnotbedeleteduntilallthehardlinkstoitareremoved.Tolinkthetwofilesabovewithahardlinktoeachotherdo:

%lnchkitchkmagThenalonglistingshowsthattheinodenumber(742)isthesameforeach:%ls-ilchkitchkmag

742-rwxr-x---2lindadbacs15927Apr2304:10chkit742-rwxr-x---2lindadbacs15927Apr2304:10chkmag



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8.1.8sort-sortfilecontentsThesortcommandisusedtoorderthelinesofafile.Variousoptionscanbeusedtochoosetheorderaswellasthefieldonwhichafileissorted.Withoutanyoptions,thesortcomparesentirelinesinthefileandoutputstheminASCIIorder(numbersfirst,uppercaseletters,thenlowercaseletters).

Syntax

sort[options][+pos1[-pos2]]file

CommonOptions-bignoreleadingblanks(&)whendeterminingstartingandendingcharactersforthesortkey-ddictionaryorder,onlyletters,digits,andaresignificant-ffolduppercasetolowercase-kkeydefsortonthedefinedkeys(notavailableonallsystems)-iignorenon-printablecharacters-nnumericsort-ooutfileoutputfile

-rreversethesort-tcharusecharasthefieldseparatorcharacter-uunique;omitmultiplecopiesofthesameline(afterthesort)+pos1[-pos2](oldstyle)providesfunctionalitysimilartothe"-kkeydef"option.

Forthe+/-positionentriespos1isthestartingwordnumber,beginningwith0andpos2istheendingwordnumber.When-pos2isomittedthesortfieldcontinuesthroughtheendoftheline.Bothpos1andpos2canbewrittenintheformw.c,wherewisthewordnumberandcisthecharacterwithintheword.Forc0specifiesthedelimiterprecedingthefirstcharacter,and1isthe

firstcharacteroftheword.Theseentriescanbefollowedbytypemodifiers,e.g.nfornumeric,btoskipblanks,etc.

Thekeydeffieldofthe"-k"optionhasthesyntax:

start_field[type][,end_field[type]]

where:

start_field,end_fielddefinethekeystorestrictthesorttoaportionofthelinetypemodifiesthesort,validmodifiersaregiventhesinglecharacters(bdfiMnr

)fromthesimilarsortoptions,e.g.atypebisequivalentto"-b",butappliesonlytothespecifiedfield



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OtherUsefulCommands

Examples

Inthefileusers:

jdoeJohnDoe4/15/96


pchenPaulChen1/5/96

jhsuJakeHsu4/17/96


sortusersyieldsthefollowing:

jdoeJohnDoe4/15/96

jhsuJakeHsu4/17/96


pchenPaulChen1/5/96


If,however,alistingsortedbylastnameisdesired,usetheoptiontospecifywhichfieldtosorton(fieldsarenumberedstartingat0):%sort+2users:pchenPaulChen1/5/96jdoeJohnDoe4/15/96jhsuJakeHsu4/17/96sphilipSuePhillip4/2/96


Tosortinreverseorder:%sort-rusers:sphilipSuePhillip4/2/96pchenPaulChen1/5/96lsmithLauraSmith3/12/96jhsuJakeHsu4/17/96jdoeJohnDoe4/15/96



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OtherUsefulCommands

8.1.9tee-copycommandoutputteesendsstandardintospecifiedfilesandalsotostandardout.Itsoftenusedincommandpipelines.

Syntax

tee[options][file[s]]

CommonOptions-aappendtheoutputtothefiles-iignoreinterruptsExamplesInthisfirstexampletheoutputofwhoisdisplayedonthescreenandstoredinthefileusers.file:

brigadier:condron[55]>who|teeusers.file

condronttyp0Apr2214:10(lcondron-pc.acs.)frankttyp1Apr2216:19(nyssa)condronttyp9Apr2215:52(lcondron-mac.acs)

brigadier:condron[56]>catusers.filecondronttyp0Apr2214:10(lcondron-pc.acs.)frankttyp1Apr2216:19(nyssa)condronttyp9Apr2215:52(lcondron-mac.acs)

Inthisnextexampletheoutputofwhoissenttothefilesusers.aandusers.b.Itisalsopipedtothewccommand,whichreportsthelinecount.

brigadier:condron[57]>who|teeusers.ausers.b|wc-l3

brigadier:condron[58]>catusers.acondronttyp0Apr2214:10(lcondron-pc.acs.)frankttyp1Apr2216:19(nyssa)condronttyp9Apr2215:52(lcondron-mac.acs)

brigadier:condron[59]>catusers.bcondronttyp0Apr2214:10(lcondron-pc.acs.)frankttyp1Apr2216:19(nyssa)condronttyp9Apr2215:52(lcondron-mac.acs)



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Inthefollowingexamplealongdirectorylistingissenttothefilefiles.long.ItisalsopipedtothegrepcommandwhichreportswhichfileswerelastmodifiedinAugust.

brigadier:condron[60]>ls-l|teefiles.long|grepAug

1drwxr-sr-x2condron512Aug81995News/2-rw-r--r--1condron1076Aug81995magnus.cshrc2-rw-r--r--1condron1252Aug81995magnus.loginbrigadier:condron[63]>catfiles.longtotal342-rw-r--r--1condron1253Oct101995#.login#1drwx------2condron512Oct171995Mail/1drwxr-sr-x2condron512Aug81995News/

5-rw-r--r--1condron4299Apr2100:18editors.txt2-rw-r--r--1condron1076Aug81995magnus.cshrc2-rw-r--r--1condron1252Aug81995magnus.login7-rw-r--r--1condron6436Apr2123:50resources.txt4-rw-r--r--1condron3094Apr1818:24telnet.ftp

1drwxr-sr-x2condron512Apr2123:56uc/1-rw-r--r--1condron1002Apr2200:14uniq.tee.txt1-rw-r--r--1condron1001Apr2015:05uniq.tee.txt~7-rw-r--r--1condron6194Apr1520:18unixgrep.txt



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OtherUsefulCommands

8.1.10uniq-removeduplicatelinesuniqfiltersduplicateadjacentlinesfromafile.

Syntax

uniq[options][+|-n]file[file.new]

CommonOptions-donecopyofonlytherepeatedlines-uselectonlythelinesnotrepeated+nignorethefirstncharacters-snsameasabove(SVR4only)-nskipthefirstnfields,includinganyblanks(&)-ffieldssameasabove(SVR4only)

Examples

Considerthefollowingfileandexample,inwhichuniqremovesthe4thlinefromfileandplacestheresultinafilecalledfile.new.

{unixprompt1}catfile1236453678907890

{unixprompt2}uniqfilefile.new

{unixprompt3}catfile.new123645367890

Below,the-noptionoftheuniqcommandisusedtoskipthefirst2fieldsinfile,andfilteroutlineswhichareduplicatesfromthe3rdfieldonward.

{unixprompt4}uniq-2file12367890



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8.1.11strings-findASCIIstringsTosearchabinaryfileforprintable,ASCII,stringsusethestringscommand.Itsearchesforanysequenceof4ormoreASCIIcharactersterminatedbyaornullcharacter.IfindthiscommandusefulforsearchingforfilenamesandpossibleerrormessageswithincompiledprogramsthatIdonthavesourcecodefor.

Syntaxstrings[options]fileCommonOptions-nnumber-number-tformat-ousenumberastheminimumstringlength,ratherthan4(SVR4only)sameasaboveprecedethestringwiththebyteoffsetfromthestartofthefile,whereformatisoneof:d=decimal,o=octal,x=hexadecimal(SVR4only)

precedethestringwiththebyteoffsetindecimal(BSDonly)Examples%strings/bin/cut

SUNW_OST_OSCMDnodelimiterspecifiedinvaliddelimiterb:c:d:f:nscut:-nmayonlybeusedwith-bcut:-dmayonlybeusedwith-fcut:-smayonlybeusedwith-fnolistspecifiedcut:cannotopen%s

invalidrangespecifiertoomanyrangesspecifiedrangesmustbeincreasinginvalidcharacterinrangeInternalerrorprocessinginputinvalidmultibytecharacterunabletoallocateenoughmemoryunabletoallocateenoughmemorycut:usage:cut-blist[-n][filename...]

cut-clist[filename...]cut-flist[-ddelim][-s][filename]



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OtherUsefulCommands

8.1.12file-filetypeThisprogram,file,examinestheselectedfileandtriestodeterminewhattypeoffileitis.Itdoesthisbyreadingthefirstfewbytesofthefileandcomparingthemwiththetablein/etc/magic.ItcandetermineASCIItextfiles,tarformattedfiles,compressedfiles,etc.

Syntax

file[options][-mmagic_file][-ffile_list]file

CommonOptions-ccheckthemagicfileforerrorsinformat-ffile_listfile_listcontainsalistoffilestoexamine-hdontfollowsymboliclinks(SVR4only)-Lfollowsymboliclinks(BSDonly)-mmagic_fileusemagic_fileasthemagicfileinsteadof/etc/magic

Examples

Belowwelisttheoutputfromthecommand"filefilename"forsomerepresentativ

efiles./etc/magic:asciitext/usr/local/bin/gzip:SundemandpagedSPARCexecutabledynamicallylinked/usr/bin/cut:ELF32-bitMSBexecutableSPARCVersion1,dynamicallylinked,strippedsource.tar:USTARtararchivesource.tar.Z:compresseddatablockcompressed16bits

8.1.13tr-translatecharactersThetrcommandtranslatescharactersfromstdintostdout.

Syntax

tr[options]string1[string2]

Withnooptionsthecharactersinstring1aretranslatedintothecharactersinstring2,characterbycharacterinthestringarrays.Thefirstcharacterinstring1istranslatedintothefirstcharacterinstring2,etc.

Arangeofcharactersinastringisspecifiedwithahyphenbetweentheupperandlowercharactersoftherange,e.g.tospecifyalllowercasealphabeticcharactersuse[a-z].

Repeatedcharactersinstring2canberepresentedwiththe[x*n]notation,wherec

haracterxisrepeatedntimes.Ifnis0orabsentitisassumedtobeaslargeasneededtomatchstring1.



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Characterscaninclude\octal(BSDandSVR4)and\character(SVR4only)notation.Here"octal"isreplacedbytheone,two,orthreeoctalintegersequenceencodingtheASCIIcharacterand

"character"canbeoneof:bbackspacefformfeednnewlinercarriagereturnttabvverticaltab

TheSVR4versionoftrallowstheoperand":class:"inthestringfieldwhereclasscantakeoncharacterclassificationvalues,including:

alphaalphabeticcharacterslowerlowercasealphabeticcharactersupperuppercasealphabeticcharacters

CommonOptions-ccomplementthecharactersetinstring1-ddeletethecharactersinstring1-ssqueezeastringofrepeatedcharactersinstring1toasinglecharacter

Examples

Thefollowingexampleswilluseasinputthefile,alistofP.G.WodehouseJeeves&Woosterbooks.

TheInimitableJeev

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