第2章Shell编程没什么多说的，记录个代码，本章最后的那个简单的CD管理程序
<!--<br /><br />Code highlighting produced by Actipro CodeHighlighter (freeware)<br />http://www.CodeHighlighter.com/<br /><br />--> # !/ bin / sh #Verysimpleexampleshellscript for managingaCDcollection. #Copyright(C) 1996 - 99 WroxPress. #Thisprogram is freesoftware;youcanredistributeitand / ormodifyit #underthetermsoftheGNUGeneralPublicLicense as publishedbythe #FreeSoftwareFoundation;eitherversion 2 oftheLicense,or(atyour #option)anylaterversion. #Thisprogram is distributed in thehopesthatitwillbeuseful,but #WITHOUTANYWARRANTY;withouteventheimpliedwarrantyof #MERCHANTABILITYorFITNESSFORAPARTICULARPURPOSE.SeetheGNUGeneral #PublicLicense for moredetails. #YoushouldhavereceivedacopyoftheGNUGeneralPublicLicensealong #with this program; if not,writetotheFreeSoftwareFoundation,Inc. # 675 MassAve,Cambridge,MA 02139 ,USA. #Thefirstthingto do is toensurethatsome global variablesthatwe ' llbeusing #throughoutthescriptare set up.We set thetitleandtrackfilesandatemporaryfile. #WealsotrapCtrl - C,soourtemporaryfile is removed if theuserinterruptsthescript. menu_choice = "" current_cd = "" title_file = " title.cdb " tracks_file = " tracks.cdb " temp_file =/ tmp / cdb.$$ trap ' rm-f$temp_file ' EXIT #Nowwedefineourfunctions,sothatthescript,executingfromthetopline,canfind #allthefunctiondefinitionsbeforeweattempttocallanyofthem for thefirsttime. #Toavoidrewritingthesamecode in severalplaces,thefirsttwofunctionsaresimple #utilities. get_return(){ echo - e " Pressreturn/c " readx return 0 } get_confirm(){ echo - e " Areyousure?/c " while true do readx case " $x " in y | yes | Y | Yes | YES) return 0 ;; n | no | N | No | NO) echo echo " Cancelled " return 1 ;; * )echo " Pleaseenteryesorno " ;; esac done } #Here,wecometothemainmenufunction,set_menu_choice. #Thecontentsofthemenuvarydynamically,withextraoptionsbeingadded if aCDentry #hasbeenselected.Notethatecho - emaynotbeportabletosomeshells. set_menu_choice(){ clear echo " Options:- " echo echo " a)AddnewCD " echo " f)FindCD " echo " c)CounttheCDsandtracksinthecatalog " if [ " $cdcatnum " != "" ];then echo " l)Listtrackson$cdtitle " echo " r)Remove$cdtitle " echo " u)Updatetrackinformationfor$cdtitle " fi echo " q)Quit " echo echo - e " Pleaseenterchoicethenpressreturn/c " readmenu_choice return } #Twomorevery short functions,insert_titleandinsert_track for addingtothedatabasefiles. #Thoughsomepeoplehateone - linerslikethese,theyhelpmakeotherfunctionsclearer #Theyarefollowedbythelargeradd_record_trackfunctionthatusesthem. #Thisfunctionusespatternmatchingtoensurenocommasareentered(sincewe ' reusingcommas # as afieldseparator),andalsoarithmeticoperationstoincrementthecurrenttracknumber # as tracksareentered. insert_title(){ echo$ * >> $title_file return } insert_track(){ echo$ * >> $tracks_file return } add_record_tracks(){ echo " EntertrackinformationforthisCD " echo " Whennomoretracksenterq " cdtrack = 1 cdttitle = "" while [ " $cdttitle " != " q " ] do echo - e " Track$cdtrack,tracktitle?/c " readtmp cdttitle = ${tmp %% , * } if [ " $tmp " != " $cdttitle " ];then echo " Sorry,nocommasallowed " continue fi if [ - n " $cdttitle " ];then if [ " $cdttitle " != " q " ];then insert_track$cdcatnum,$cdtrack,$cdttitle fi else cdtrack = $((cdtrack - 1 )) fi cdtrack = $((cdtrack + 1 )) done } #Theadd_recordsfunctionallowsentryofthemainCDinformation for a new CD. add_records(){ #Prompt for theinitialinformation echo - e " Entercatalogname/c " readtmp cdcatnum = ${tmp %% , * } echo - e " Entertitle/c " readtmp cdtitle = ${tmp %% , * } echo - e " Entertype/c " readtmp cdtype = ${tmp %% , * } echo - e " Enterartist/composer/c " readtmp cdac = ${tmp %% , * } #Checkthattheywanttoentertheinformation echoAbouttoadd new entry echo " $cdcatnum$cdtitle$cdtype$cdac " #Ifconfirmedthenappendittothetitlesfile if get_confirm;then insert_title$cdcatnum,$cdtitle,$cdtype,$cdac add_record_tracks else remove_records fi return } #Thefind_cdfunctionsearches for thecatalognametext in theCDtitlefile, using the #grepcommand.Weneedtoknowhowmanytimesthe string wasfound,butgreponlyreturns #avaluetellingus if itmatchedzerotimesormany.To get around this ,westorethe #output in afile,whichwillhaveonelinepermatch,thencountthelines in thefile. #Thewordcountcommand,wc,haswhitespace in itsoutput,separatingthenumberoflines, #wordsandcharacters in thefile.Weusethe$(wc - l$temp_file)notationtoextractthe #firstparameterfromtheoutputto set thelinesfoundvariable.Ifwewantedanother, #laterparameterwewouldusethe set commandto set theshell ' sparametervariablesto #thecommandoutput. #WechangetheIFS(InternalFieldSeparator)toa,(comma),sowecanseparatethe #comma - delimitedfields.Analternativecommand is cut. find_cd(){ if [ " $1 " = " n " ];then asklist = n else asklist = y fi cdcatnum = "" echo - e " EnterastringtosearchforintheCDtitles/c " readsearchstr if [ " $searchstr " = "" ];then return 0 fi grep " $searchstr " $title_file > $temp_file set $(wc - l$temp_file) linesfound = $ 1 case " $linesfound " in 0 )echo " Sorry,nothingfound " get_return return 0 ;; 1 );; 2 )echo " Sorry,notunique. " echo " Foundthefollowing " cat$temp_file get_return return 0 esac IFS = " , " readcdcatnumcdtitlecdtypecdac < $temp_file IFS = " " if [ - z " $cdcatnum " ];then echo " Sorry,couldnotextractcatalogfieldfrom$temp_file " get_return return 0 fi echo echoCatalognumber:$cdcatnum echoTitle:$cdtitle echoType:$cdtype echoArtist / Composer:$cdac echo get_return if [ " $asklist " = " y " ];then echo - e " ViewtracksforthisCD?/c " readx if [ " $x " = " y " ];then echo list_tracks echo fi fi return 1 } #update_cdallowsustore - enterinformation for aCD.Noticethatwesearch(grep) # for linesthatstart( ^ )withthe$cdcatnumfollowedbya,,andthatweneedtowrap #theexpansionof$cdcatnum in {}sowecansearch for a,withnowhitespacebetween #itandthecataloguenumber.Thisfunctionalsouses{}toenclosemultiplestatements #tobeexecuted if get_confirmreturns true . update_cd(){ if [ - z " $cdcatnum " ];then echo " YoumustselectaCDfirst " find_cdn fi if [ - n " $cdcatnum " ];then echo " Currenttracksare:- " list_tracks echo echo " Thiswillre-enterthetracksfor$cdtitle " get_confirm && { grep - v " ^${cdcatnum}, " $tracks_file > $temp_file mv$temp_file$tracks_file echo add_record_tracks } fi return } #count_cdsgivesusaquickcountofthecontentsofourdatabase. count_cds(){ set $(wc - l$title_file) num_titles = $ 1 set $(wc - l$tracks_file) num_tracks = $ 1 echofound$num_titlesCDs,withatotalof$num_trackstracks get_return return } #remove_recordsstripsentriesfromthedatabasefiles, using grep - vtoremoveall #matchingstrings.Noticewemustuseatemporaryfile. #Ifwetriedto do this , #grep - v " ^$cdcatnum " > $title_file #the$title_filewouldbe set toemptybythe > outputredirectionbeforethegrep #hadchancetoexecute,sogrepwouldreadfromanemptyfile. remove_records(){ if [ - z " $cdcatnum " ];then echoYoumustselectaCDfirst find_cdn fi if [ - n " $cdcatnum " ];then echo " Youareabouttodelete$cdtitle " get_confirm && { grep - v " ^${cdcatnum}, " $title_file > $temp_file mv$temp_file$title_file grep - v " ^${cdcatnum}, " $tracks_file > $temp_file mv$temp_file$tracks_file cdcatnum = "" echoEntryremoved } get_return fi return } #List_tracksagainusesgreptoextractthelineswewant,cuttoaccessthefields #wewantandthenmoretoprovideapaginatedoutput.Ifyouconsiderhowmanylines #ofCcodeitwouldtaketore - implementthese 20 - oddlinesofcode,you ' llappreciate #howpowerfulatooltheshellcanbe. list_tracks(){ if [ " $cdcatnum " = "" ];then echonoCDselectedyet return else grep " ^${cdcatnum}, " $tracks_file > $temp_file num_tracks = $(wc - l$temp_file) if [ " $num_tracks " = " 0 " ];then echonotracksfound for $cdtitle else { echo echo " $cdtitle:- " echo cut - f 2 - - d,$temp_file echo } | ${PAGER: - more} fi fi get_return return } #Nowallthefunctionshavebeendefined,wecanenterthemainroutine. #Thefirstfewlinessimply get thefilesintoaknownstate,thenwecallthemenu #function,set_menu_choice,andactontheoutput. #Whenquit is selected,wedeletethetemporaryfile,writeamessageandexit #withasuccessfulcompletioncondition. rm - f$temp_file if [ ! - f$title_file];then touch$title_file fi if [ ! - f$tracks_file];then touch$tracks_file fi #Nowtheapplicationproper clear echo echo echo " MiniCDmanager " sleep 1 quit = n while [ " $quit " != " y " ]; do set_menu_choice case " $menu_choice " in a)add_records;; r)remove_records;; f)find_cdy;; u)update_cd;; c)count_cds;; l)list_tracks;; b) echo more$title_file echo get_return;; q | Q)quit = y;; * )echo " Sorry,choicenotrecognized " ;; esac done #Tidyupandleave rm - f$temp_file echo " Finished " exit 0 相关资源：敏捷开发V1.0.pptx