北大 internet高级程序设计 lecture5-Makefile课件.ppt

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1、Lecture5MakefileIntroductionThe“make”utilityinUnixisoneoftheoriginaltoolsdesignedbyS.I.FieldmanofAT&TBelllabscirca1977.Therearemanyversion.Whatis“make”?:Thetoolisdesignedtoallowprogrammerstoefficientlycompilelargecomplexprogramswithmanycomponentseasily.Youcanplacethecommandst

2、ocompileaprograminaUnixscriptbutthiswillcauseALLmodulestobecompiledeverytime.The“make”utilityallowsustoonlycompilethosethathavechangedandthemodulesthatdependuponthem.HowDoesitWork?InUnix,whenyoutypethecommand“make”theoperatingsystemlooksforafilecalledeither“makefile”or“Makefi

3、le”.Thereareexceptionstothisbutwewillassumethatyouwillalwayshavethe“makefile”or“Makefile”fileresidentinthedirectoryofwhereyourprogramresides.Thisfilecontainsaseriesofdirectivesthattellthe“make”utilityhowtocompileyourprogramandinwhatorder.Eachfilewillbeassociatedwithalistofoth

4、erfilesbywhichitisdependent.Thisiscalledadependencyline.Ifanyoftheassociatedfileshavebeenrecentlymodified,themakeutilitywillexecuteadirectivecommandjustbelowthedependencyline.HowDoesitWork?The“make”utilityisrecursive.Forinstance,ifaverylowlevelutilityistheonlythingchanged,itc

5、ouldcauseallofthemoduleswithinaprogramtobere-compiled.Aftertheutilityfinishesthefile,itgoesthroughandchecksallofthedependenciesagaintomakesureallareuptodate.SimpleExamplehello:main.ofactorial.ohello.og++main.ofactorial.ohello.o-ohellomain.o:main.cppg++-cmain.cppfactorial.o:fa

6、ctorial.cppg++-cfactorial.cpphello.o:hello.cppg++-chello.cppclean:rm-rf*ohelloTheTreehellomain.ofactorial.ofactorial.cppmain.cppfactorial.ohello.ohello.cppcleanComponentsofaMakefileCommentsRulesDependencyLinesShellLinesMacrosInferenceRulesCommentsAcommentisindicatedbythechara

7、cter“#”. Alltextthatappearsafteritwillbeignoredbythemakeutilityuntiltheendoflineisdetected.Commentscanstartanywhere. Therearemorecomplexcommentstylesthatinvolvecontinuationcharactersbutpleasestarteachnewcommentlinewithan#andavoidthemoreadvancedfeaturesfornow.Example##Thisisac

8、ommentprojecte.exe:main.objio.obj#thisisalsoacomment.RulesRulestellm