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[Powered by Google Translate] Tommy: F'dan il-video, aħna ser jitgħallmu dwar

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ridirezzjonar u pajpijiet.

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S'issa, aħna kont qed tuża l-funzjonijiet simili printf li

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output data lill-terminal u l-funzjonijiet simili GetString

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li jippermetti lill-utent biex jipprovdi kontribut lill tagħna

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Programm użu tal-keyboard.

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Ejja malajr tagħti ħarsa lejn programm li gets linja ta '

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input mill-utent u mbagħad outputs tiegħu.

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>> Fuq il-linja 7, aħna qed wassal lill-utent għal string, u

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imbagħad fuq il-linja 8, aħna qed istampar lura out.

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Ejja tiġbor u tmexxi programm tagħna.

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Great.

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L-sekwenza we pprovduti ġie mtenni lura

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lilna fit-terminal.

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Dan ġara minħabba l-funzjoni printf kiteb lil

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nixxiegħa jissej standard, jew s-t-d-out.

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Meta xi ħaġa huwa miktub biex stdout, huwa fil-kontumaċja

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murija mit-terminal.

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>> Allura li kollox sew u tajjeb, imma dak jekk, minflok sempliċiment

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juri l-sekwenza, ridna li tiffranka lill fajl?

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Per eżempju, aħna tista 'tixtieq li tiftakar eżattament dak tagħna

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Programm għamlet meta aħna tatha 'dħul partikolari tard.

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Approċċ wieħed ikun li tagħmel dan fil-programm C tagħna, bl-użu

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xi funzjonijiet speċjali għall-kitba għall-fajls li aħna ser

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tara ieħor video.

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Anki faċli, għalkemm, ikun li b'xi mod

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idawwru stdout għal fajl.

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B'dan il-mod, meta printf jikteb lill stdout, il-kontenut se

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tkun bil-miktub għall-fajl minflok

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murija mit-terminal.

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Nistgħu tagħmel dan billi żżid sinjal akbar minn dak, segwita

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minn isem ta 'fajl, il-kmand nużaw biex tesegwixxi programm tagħna.

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>> Allura, aktar milli sempliċement jeżegwixxi. / Idawwru, nistgħu

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run. / idawwru, segwita minn aktar minn sinjal, segwita minn

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isem tal-file, bħall file.txt.

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Ejja naraw x'jiġri.

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OK.

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Avviż li din id-darba, xejn kien murija fit-terminal,

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iżda aħna ma mmodifikawx-kontenut ta 'tagħna

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Programm C fil-livelli kollha.

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Ejja issa teżamina l-kontenut ta 'dan id-direttorju ma' ls.

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>> Kull dritt.

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Issa għandna fajl ġdid fl-direttorju tagħna imsejħa file.txt,

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li huwa l-isem ta 'fajl aħna fornuti meta aħna dam tagħna

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Direzzjoni ġdida program.

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Ejja jiftħu file.txt.

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U hawn, nistgħu naraw li l-stdout minn idawwru kien

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bil-miktub lill-fajl imsejjaħ file.txt.

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Mela ejja imexxu l-kmand preċedenti mill-ġdid, iżda jfornu

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input differenti dan iż-żmien.

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Okay.

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Ejja tagħti ħarsa lejn file.txt issa.

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>> Nistgħu naraw hawn li l-fajl kien miktub fuq ieħor, hekk tagħna

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input oriġinali ma jkunx hemm aktar.

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Jekk aħna minflok trid tehmeż dan il-fajl, it-tqegħid l-ġdid

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input taħt il-kontenut eżistenti tal-fajl, nistgħu

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jużaw żewġ ikbar minn sinjali 'minflok waħda biss.

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Ejja nippruvaw dan.

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Issa, jekk aħna miftuħa file.txt darb'oħra, nistgħu naraw kemm ta 'tagħna

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input linji.

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F'xi każijiet, aħna tista 'tixtieq li jarmi xi

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produzzjoni tal-programm tagħna.

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Pjuttost milli bil-miktub l-output għall-fajl u imbagħad tħassar

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il-fajl meta aħna qed isir ma 'dan, nistgħu jiktbu lill speëjali

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fajl imsejjaħ / DEV / null.

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Meta xi ħaġa huwa miktub lil / dev/null--

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jew biss devnull-qasir -

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huwa awtomatikament tintrema.

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Allura taħseb devnull bħala toqba sewda għall-informazzjoni tiegħek.

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>> Allura issa Rajna kif il-sinjal akbar milli jista idawwru

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stdout, ejja ara kif nistgħu idawwru standard -

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jew s-t-d-in -

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l-analogu ta 'stdout.

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Filwaqt li l-funzjonijiet simili printf jikteb lill-nixxiegħa imsejħa

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, stdout GetString u funzjonijiet simili aqra mill-fluss

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imsejħa stdin, li, awtomatikament, hija l-fluss ta '

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karattri ttajpjati fuq il-keyboard.

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Nistgħu idawwru stdin bl-użu inqas minn sinjal, segwita

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minn isem tal-file.

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Issa, minflok wassal lill-utent għall-input fil-

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terminal, programm se tiftaħ il-fajl aħna speċifikati u l-użu

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Linji tagħha bħala input.

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>> Ejja naraw x'jiġri.

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Great.

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L-ewwel linja ta 'file.txt ġiet stampata għat-terminal

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għaliex aħna qed titlob GetString darba.

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Jekk kellna sejħa oħra għall GetString fil-programm tagħna, il-

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linja li jmiss ta 'file.txt kienu użati bħala

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kontribut għal dik is-sejħa.

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Għal darb'oħra, aħna ma mmodifikawx programm C tagħna fil-livelli kollha.

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Aħna biss tinbidel kif aħna run.

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U wkoll ftakar, aħna ma dirottati stdout dan iż-żmien,

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hekk l-output tal-programm kien għadu

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murija fit-terminal.

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Nistgħu, naturalment, idawwru kemm stdin

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u stdout bħal dan.

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Issa, file2.txt fiha l-ewwel linja ta 'file.txt.

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>> Allura, jużaw dawn l-operaturi, aħna kont qed kapaċi li jaqra u

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tikteb mill-fajls test.

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Issa, ejja ara kif nistgħu nużaw l-output ta 'programm wieħed kif

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l-input għal programm ieħor.

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Allura hawnhekk programm ieħor C sempliċi I

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jkunu hawn imsejħa hello.c.

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Kif tistgħu taraw, dan sempliċement outputs "Hi

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hemm! "għall-utent.

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Jekk irrid idawwru għall-użu bħala input-output ta bonjour -

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programm ieħor -

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I jistgħu idawru l-1 stdout ta bonjour għal fajl imsejjaħ

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input.txt, mbagħad jagħtu direzzjoni ġdida l-stdin ta idawwru għal dak istess

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fajl -. input.txt

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So I tista 'tagħmel. / Bonjour> input.txt.

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Agħfas Ikteb li jesegwixxi din.

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Segwit minn. / Idawwru <

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input.txt, u tesegwixxi dik.

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Allura aħna jista 'jqassar dan daqsxejn bil-punto virgola, li tippermetti

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us jiddekorri tnejn jew aktar jikkmanda fuq l-istess linja.

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Allura nista 'ngħid,. / Bonjour> input.txt, virgola,

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. / Idawwru <input.txt.

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>> Allura dan jaħdem, iżda għadu jħoss pjuttost inelegant.

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I mean, aħna verament bżonn dan il-fajl test intermedjarju li l-

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m'għadx hemm bżonn wara idawwru runs?

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Fortunatament, nistgħu jevitaw dan il-fajl test żejjed bl-użu x'hemm

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imsejħa pajp.

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Jekk I say, / bonjour |.. / Idawwru, allura l-stdout ta

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il-programm fuq ix-xellug -

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f'dan il-każ, bonjour -

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se jintużaw bħala l-input standard għall-

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programm fuq il-lemin.

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F'dan il-każ, idawwru. Mela ejja run dan.

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>> Hemm immorru.

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Nistgħu naraw li l-output ta 'bonjour kien użat bħala l-input

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għal direzzjoni ġdida.

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Billi stringing jikkmanda flimkien bl-użu pajpijiet, aħna jiffurmaw x'hemm

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imsejħa pipeline, peress produzzjoni tagħna hija bażikament jitneħħew

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permezz ta 'sekwenza ta' kmandi.

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Bl-użu pajpijiet, nistgħu nagħmlu xi għalf jibred mingħajr il-bżonn li

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jikteb xi kodiċi fil-livelli kollha.

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Per eżempju, ejja ngħidu li rridu nkunu nafu kemm fajls huma

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ġewwa ta 'dan id-direttorju.

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Permezz ta 'pajp, nistgħu jgħaqqdu l-kmand ls mal-WC -

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jew wordcount -

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kmand.

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Ls se output kull fajl fil-direttorju li stdout, u

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wc se jgħidulna kemm linji ngħataw lilha permezz stdin.

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Għalhekk, jekk irridu ngħidu ls | wc-l -

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jfornu l-bandiera l għal wc li tgħid li jgħodd linji -

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nistgħu naraw eżattament kemm fajls huma

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fid-direttorju kurrenti.

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>> Mela ejja tagħti ħarsa lejn eżempju wieħed aktar.

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Għandi hawnhekk l-inkartament imsejjaħ students.txt,

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ma 'lista ta' ismijiet.

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Madankollu, dawn l-ismijiet ma jkunux fi kwalunkwe ordni dan kollu, u jidher

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bħal ftit ismijiet huma ripetuti.

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Dak li rridu hija lista ta 'ismijiet uniċi fil alfabetika

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ordni, ffrankati l-fajl imsejjaħ final.txt.

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Nistgħu, naturalment, jikteb programm C biex jagħmlu dan għalina.

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Iżda li għaddej biex tikseb bla bżonn

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kumpless pretty malajr.

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Ejja minflok jużaw pajpijiet u xi mibnija fil-għodod biex isolvu

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din il-problema.

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>> L-ewwel ħaġa li għandna bżonn tagħmel hu li jaqra l-students.txt fajl.

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Il-kmand qattus se tagħmel dan.

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Hija ser jinqara fil-fajl speċifikat u jiktbu

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kontenuti tiegħu mal stdout.

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Wara konna jaqra l-fajl test, aħna ser

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tixtieq li sort l-ismijiet.

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Il-kmand tip jistgħu jimmaniġġjaw dan għalina.

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Sort se output-linja fornita permezz stdin li stdout

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sabiex magħżula.

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Sabiex jipprovdu l-kontenut ta 'students.txt lil

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stdin sort, aħna jistgħu jużaw pajp li jgħaqqad qtates u tip.

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So I tista 'tesegwixxi qattus students.txt | sort u

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istampa Ikteb.

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U issa, naraw il-kontenut ta students.txt fil

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alfabetiku ordni.

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>> Mela ejja żid ieħor kmand -

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uniq, jew uniku -

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għall pipeline tagħna.

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Kif inti tista raden, uniq, meta fornuti sekwenza magħżula ta '

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Linji permezz stdin, se output-linji uniċi.

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Allura issa għandna students.txt qattus

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| Sort | uniq.

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Fl-aħħarnett, aħna jista 'jiffranka l-output tal-pipeline lejn

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fajl permezz qattus students.txt | sort | uniq

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> Final.txt.

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Għalhekk, jekk irridu jiftħu final.txt, għandna eżattament dak li konna

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tfittex:

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lista ta 'ismijiet uniku fl-ordni alfabetika,

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ffrankati l-fajl test.

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Mill-mod, aħna wkoll jista 'jkollhom qal sort <

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students.txt | uniq> final.txt tagħmel eżattament

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l-istess ħaġa, bl-użu kull wieħed mill-operaturi aħna stajt tidher fil

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dan il-video.

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>> Jisimni Tommy, u dan huwa CS50.