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CSE 391Lecture 1

introductiontoLinux/Unixenvironment

slidescreatedbyMartyStepp,modifiedbyJessicaMiller,RuthAnderson,andBrettWortzmanhttp://www.cs.washington.edu/391/

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Lecture summary• Courseintroductionandsyllabus

• UnixandLinuxoperatingsystem

• IntroductiontoBashshell

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Course Introduction• Instructor:§ Zorah Fung,zorahf@cs§ CSE2311§ OH:Tues,2:30-3:30pm

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Course Introduction• TA:

§ JoshErvin,joshue@uw

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Course Introduction• Website:http://cs.washington.edu/391

§ CollectionoftoolsandtopicsnotspecificallyaddressedinothercoursesthatCSEmajors(andinterestedothers)shouldknow§ CSE351maybethefirstcourseyoutakethatusesLinux

§ Credit/NoCreditcourse,determined byweeklyassignments§ Gradedprimarilyoneffort/completion

§ “Textbook” – LinuxPocketGuide§ Optionalbutrecommended; veryusefulguide

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Course Topics• Linuxcommandlineinterface(CLI)• Shellcommands• Usersandgroups• Permissions• Shellscripting• Regularexpressions• Projectmanagementtools(e.g.makefiles)• Versioncontrol(e.g.git)

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Homework/Grading• ~Nineweeklyassignments

§ Releasedafterlecture§ DuefollowingTuesday,1:00pm(nolateworkaccepted)

• Basedonmaterialcovered inthatweek’s lecture§ Afew“self-discovery” extensions§ Allrequired informationinlecture,slides,book,and/ormanpages

• Gradedoutof2pointseach§ Primarilydetermined byeffort/completion (seesyllabus)§ Totalof14pointsrequired toreceive creditforthecourse

• TobecompletedonLinux/Unixsystems(nextslide)• Collaborationallowed/encouraged, butALLSUBMITTEDWORKMUSTBEYOUROWN

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Accessing Linux/UnixRoughlyinsuggestedorder…•ssh toattu (CSEmajors),linuxNN (EEmajors),orovid (allUWstudents)

• Download/runCSEVM• VisitCSorEEbasement labs• SetupLinuxonyourownmachine

• See“WorkingatHome”oncoursewebsiteformoreinfo

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Operating systems• WhatisanOS?Whyhaveone?

• WhatisaKernel?

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Operating systems• operatingsystem:Managesactivitiesandresourcesofacomputer.

§ softwarethatactsasaninterfacebetweenhardwareanduser§ providesalayerofabstractionforapplicationdevelopers

• featuresprovidedbyanoperatingsystem:§ abilitytoexecuteprograms (andmulti-tasking)§ memorymanagement (andvirtualmemory)§ filesystems,diskandnetworkaccess§ aninterfacetocommunicatewithhardware§ auserinterface (oftengraphical)

• kernel:Thelowest-levelcoreofanoperatingsystem.

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Unix• briefhistory:

§ Multics(1964)formainframes§ Unix(1969)§ K&R§ LinusTorvaldsandLinux(1992)

• keyUnixideas:§ writteninahigh-level language(C)§ virtualmemory§ hierarchicalfilesystem; "everything" isafile§ lotsofsmallprogramsthatworktogethertosolvelargerproblems§ security,users,access,andgroups§ human-readabledocumentation included

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Linux• Linux:Akernel foraUnix-likeoperatingsystem.

§ commonly seen/usedtodayinservers,mobile/embedded devices,...

• GNU:A"freesoftware"implementation ofmanyUnix-liketools§ manyGNUtoolsaredistributedwiththeLinuxkernel

• distribution: Apre-packagedsetofLinuxsoftware.§ examples:Ubuntu,Fedora,CentOS

• keyfeaturesofLinux:§ opensourcesoftware:sourcecanbedownloaded§ freetouse§ constantlybeingimproved/updatedbythecommunity

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Linux Desktop• X-windows• windowmanagers• desktopenvironments

§ Gnome§ KDE

• HowcanItryoutLinux?§ CSEVirtualmachine§ CSEbasementlabs§ attu sharedserver

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Things you can do in Linux• Loadthecoursewebsiteinabrowser

• Installandplaygames

• PlayMP3s

• Editphotos

• IM,Skype

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Shell• shell:Aninteractiveprogramthatusesuserinputtomanagetheexecutionofotherprograms.§ Acommandprocessor,typicallyrunsinatextwindow.§ Usertypescommands,theshellrunsthecommands§ Severaldifferentshellprogramsexist:

•bash :thedefaultshellprogramonmostLinux/Unixsystems• Wewillusebash• Othershells:Bourne,csh,tsch

• WhyshouldIlearntouseashellwhenGUIsexist?

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Why use a shell?• WhyshouldIlearntouseashellwhenGUIsexist?

§ faster§ workremotely§ programmable§ customizable§ repeatable

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Example shell commands

$ pwd/homes/iws/rea$ cd CSE391$ lsfile1.txt file2.txt$ ls –l-rw-r--r-- 1 rea fac_cs 0 2017-03-29 17:45 file1.txt-rw-r--r-- 1 rea fac_cs 0 2017-03-29 17:45 file2.txt$ cd ..$ man ls$ exit

command descriptionpwd printthecurrentworkingdirectorycd changestheworkingdirectoryls listsfilesinadirectoryman bringsupthemanualforacommandexit logsoutoftheshell

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System commands

• "manpages"areaveryimportantwaytolearnnewcommandsman lsman man

command descriptionman or info gethelponacommandclear clearsouttheoutputfromtheconsoleexit exitsandlogsoutoftheshelldate outputthesystemdatecal outputatextcalendaruname printinformationaboutthecurrentsystem

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Relative directoriesdirectory description

. thedirectoryyouarein("workingdirectory")

.. theparentoftheworkingdirectory(../.. isgrandparent,etc.)

~ yourhome directory(onmanysystems,thisis/home/username )

~username username'shome directory

~/Desktop yourdesktop

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Unix file systemdirectory description

/ rootdirectorythatcontainsallothers(drivesdonothavelettersinUnix)

/bin programs/dev hardwaredevices/etc systemconfigurationfiles

§ /etc/passwd storesuserinfo§ /etc/shadow storespasswords

/home users'homedirectories/media,/mnt,...

drivesandremovabledisksthathavebeen"mounted"foruseonthiscomputer

/proc currentlyrunningprocesses(programs)/tmp, /var temporaryfiles/usr user-installedprograms

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Directory commands

• somecommands(cd,exit)arepartoftheshell("builtins")• others(ls,mkdir)areseparateprogramstheshellruns

command descriptionls listfilesinadirectorypwd printthecurrentworkingdirectorycd changestheworkingdirectorymkdir createanewdirectoryrmdir deleteadirectory(mustbeempty)

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Command-line arguments• manyacceptarguments orparameters

§ example:cp (copy)acceptsasourceanddestinationfilepath

• aprogramuses3streamsofinformation:§ stdin,stdout,stderr(standardin,out,error)

• input:comesfromuser'skeyboard• output:goestoconsole• errors canalsobeprinted (bydefault,senttoconsolelikeoutput)

• parametersvs.input§ parameters: beforeEnterispressed;sentinbyshell§ input: afterEnterispressed;sentinbyuser

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Command-line arguments• mostoptionsarea- followedbyalettersuchas-c

§ somearelongerwordsprecededbytwo- signs,suchas--count

• optionscanbecombined:ls -l -a -r canbels -lar

• manyprogramsaccepta--help or-help optiontogivemoreinformationaboutthatcommand(inadditiontoman pages)§ orifyouruntheprogramwithnoarguments, itmayprinthelpinfo

• formanycommandsthatacceptafilenameargument, ifyouomittheparameter, itwillreadfromstandardinput(yourkeyboard)

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File commands

• caution:theabovecommandsdonotpromptforconfirmation§ easytooverwrite/delete afile; thissettingcanbeoverridden (how?)

• Exercise:Givenseveralalbumsof.mp3 filesallinonefolder,movethemintoseparatefoldersbyartist.

• Exercise:Modifya .java file tomakeitseemasthoughyoufinishedwritingitonDec28at4:56am.

command descriptioncp copyafilemv moveorrenameafilerm deleteafiletouch createanewemptyfile,or

updateitslast-modifiedtimestamp

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Exercise Solutions • caution:thecp,rm,mvcommandsdonotpromptforconfirmation

§ easytooverwrite/delete afile; thissettingcanbeoverridden (how?)• Use“-i”withthecommand,“interactive”topromptbeforeoverwrite

• Exercise:Givenseveralalbumsof.mp3 filesallinonefolder,movethemintoseparatefoldersbyartist.§ mkdir U2§ mkdir PSY§ mkdir JustinBieber § mv GangnamStyle.mp3 PSY/§ mv Pride.mp3 U2/

• Exercise:Modifya .java file tomakeitseemasthoughyoufinishedwritingitonDec28at4:56am.§ touch –t "201812280456" Hello.java

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Text editors

• youcannotrungraphicalprogramswhenconnectedtoattu (yet)§ soifyouwanttoeditdocuments,youneedtouseatext-onlyeditor

• mostadvancedUnix/Linux userslearnemacs orvi§ Iwouldrecommendyoutrytopickupthebasicsofoneofthese.§ Yourchoice!

command descriptionpico or nano simpleeditorsemacs Moreadvancedtexteditorvi or vim Moreadvancedtexteditor

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Basic Emacs Commands• C- =controlkey M- =meta/altkey• readafileintoEmacs: C-xC-f• saveafilebacktodisk: C-xC-s• exitEmacs permanently: C-xC-c• searchforward: C-s searchbackward: C-r• scrolltonextscreen: C-v scrolltopreviousscreen: M-v• Undo: C-xu

entitytomoveover backward forward

character C-b C-f

word M-b M-f

line C-p C-n

gotolinebeginning/end C-a C-e

gotobufferbeginning/end M-< M->

https://courses.cs.washington.edu/courses/cse391/18sp/handouts/emacs.pdf

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Basic Vim Commands• :w Writethecurrentfile• :wq Writethecurrentfileandexit.• :q!Quitwithoutwriting• Tochangeintoinsertmode:i ora

§ Useescape toexit• searchforward/,repeatthesearchbackwards:N• Basicmovement:

§ hlkj character left,right;lineup,down(alsoarrowkeys)§ bw word/tokenleft,right§ ge e endofword/tokenleft,right§ 0$ jumptofirst/lastcharacterontheline

• x delete• u undo

https://wiki.gentoo.org/wiki/Vim/Guide and http://tnerual.eriogerg.free.fr/vimqrc.pdf