UNIX常用命令
UnixDevelopmentEnvironment
lTheBasicKnowleage lTheGeneralCommand lUnixShell lMakeFile |
TheBasicKnowledge
Unix/linuxsystemsaremulti-userandmulti-tasking lHavemultipleusersonthesamesystem lRunmultiplePRograms,seeminglysimultaneously lMaintainpermissionsthatdeterminewhichusershaveaccesstowhickfilesandprograms lRegulatetheamountofdiskspaceeachusercanuse lStoreuser-specificsettingsin“hidden”file |
LoggingIn
lWhenyoufirstconnecttooneoftheUnixcomputersyouwillseetheprompt: lLogin: Atthelogin:prompt,typeinyourusernamePassWord Onceyouhavetypedinyourusernameyouwillbepromptedtotypeinyourpassword |
InitializationFiles
WhenyoulogintheUnix/Linuxloginprogramfinally,startsupacommand“shell” UsersdonotdealwiththeOperatingsystemdirectly.MostofyourinteractionwithaUnixsystemtakesplaceinashell,aprogramthatisruneverytimeyoulogin,anddisplaysthe“$”prompt.Theshellisknownascommandinterpreter,yougiveitcommands,anditrunsthem. |
Shell
lSh | lBourneShell |
lKsh | lKornShell |
lCsh | lCshellbasedonClanguage |
lBash | lBornAgainShell |
lTcsh | lanotherversionofCshell |
UsingtheSystem
Finallyyouareloggedin!Youwillseeapromptlikeoneofthefollowing: $/# Justwaitingfoyoutotypesomething.Wewilluser$toindicatethecomputer’s“ready”prompt. Okey,let’stryasimplecommand. |
ls
lsistheprogramtolistfilesinadirectory.Justplainlswon’tlisthiddenfiles(fileswhosenamesstartwith``.’’,like.login).Nowtrytyping: ls-a |
pwd(printworkingdirectory)
Tofindoutwhichdirectoryyouarein,type: pwd Thiswillshowyouthefullpathtoyourcurrentworkingdirectory,relativetotherootdirectory(/). |
Rm(removefilesordirectories)
Thecommandrmfilewillremovethespecifiedfile. Someusefuloptionsforrminclude rm-i(interactivemode-youwillbepromptedtocomfirmfiledeletion) rm-f(forceremove-overridesinteractivemodeandremovesfilewithoutaprompt) rm-r(recursive-removethecontentsofdirectoriesrecursively) |
cp(copyfilesanddirectories)
Tocopyafile,do: cpoldfilenamenewfilename Ortocopyafiletoanewdirectory,whilekeepingtheoldfilenamedo: cpfilename/directoryname/ Toensureyourdon’toverwriteanyexistingfilesyoucanusethe‘-i’option: cp-ioldfilenamenewfilename Thiscommandwillpromptyoutoconfirmifthereisalreadyafilewiththenamenewfilename. |
mv(movefiles)
Thiscommandallowsyoutorenameafileasin: mvoldfilenamenewfilename Ortomoveafiletoanewdirectory: mvfilenamedirectoryname/ Aswithcp,itisagoodideatousethe‘-i’optionwithmv,soyoudon’tmistakenlyoverwriteyourexistingfiles. |
Thespecialdirectory
Youmayhavenoticedwhenyoutypedls–athattherewerelistingsdot(.)anddot-dot(..).Theserepresentyourcurrentworkingdirectory(.)andit’sparentdirectory(..). Forexample,typing cd.. cd. cp/vol/examples/tutorial/science.txt. cd~willalwaysbringyoubacktoyourhomedirectory. cd~/homeworkwillbringyoutothe‘homework’directory. Thecharacter*iscalledawildcardandwillmatchagainstnoneofmorecharacter(s)inafileordirectoryname. Forexample,ifyoutype ls*h Youshouldgetalistofallfilesanddirectoriesstartingwiththeletterh. Similarlyifyoutype: ls*.cpp The?characterissimilartothe*character,exceptthat?willmatchexactlyonecharacter,Forexample: ls?anwillmatch‘man’butnot‘stan’! |
Displaythecontentsofafileonthescreen
clear(clearscreen)
Beforeyoustartthenextsection,youmayliketocleartheterminalwindowofthepreviouscommandssotheoutputofthefollowingcommandscanbeclearlyunderstood. Attheprompt,type clear Thiswillclearalltextandleaveyouwiththe%promptatthetopofthewindow. |
cat(concatenate)
Thecommandcatcanbeusedtodisplaythecontentsofafileonthescreen.Type: catscience.txt |
asyoucansee,thefileislongerthanthesizeofthewindow,soitscrollspastmakingitunreadable.
less
Thecommandlesswritesthecontentsofafilenotothescreenapageatatime,type: lessscience.txt Pressthe[space-bar]ifyouwanttoseeanotherpage,type[q]ifyouwanttoquitreading. |
head
Theheadcommandwritesthefirsttenlinesofafiletothescreen. Firstclearthescreenthentype headscience.txt |
tail
thetailcommandwritesthelasttenlinesofafiletothescreen.Clearthescreenandtype: tailscience.txt |
Searchingthecontentsofafile
Simplesearchingusingless
Usingless,youcansearchthoughatextfileforakeyword(pattern).Forexample,tosearchthroughscience.txtfortheword‘science’,type lessscience.txt Thenstillinless(i.e.don’tpress[q]toquit),typeaforwardslash[/]followedbythewordtosearch. Asyoucansee,lessfindsandhighlightsthekeyword.Type[n]tosearchforthenextoccurrenceoftheword. |
grep
Itsearchesfilesforspecifiedwordsorpatterns.Firstclearthescreen,thentype grepsciencescience.txt Asyoucansee,grephasprintedouteachlinecontainingthewordscience. Trytyping grepSciencescience.txt Thegrepcommandsiscasesensitive;ItdistinguishesbetweenScienceandscience. Toignoreupper/lowercasedistinctions,usethe-ioption,i.e.Type grep-isciencescience.txt TosearchforapharSEOrpattern,youmustencloseitinsinglequotes.Forexampletosearchforspinningtop.Type
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