stderrcrontab

LinuxProductivityToolsKetanM.
(km0@ornl.
gov)OakRidgeNationalLaboratory1LISA19October2019Portland,OR,USATableofContentsPart1:OverviewandLogisticsPart2:BasicsPart3:Streams,pipeandredirectionPart4:ClassicTools:find,grep,awk,sedPart5:SessionManagement:tmuxPart6:ssh:configandtunnelingPart7:BashToolsPart8:MiscellaneousUtilitiesSummaryPracticeandExercises(iftimepermitselseOffline)2Part1:OverviewandLogistics3backtotocorientationandpracticalstuffOverview:WhatshallwelearnBuildpowerfulcommand-linesWewilluseBashshellwithdefaultkey-bindingsWewillassumeGNU/LinuxandcallitLinuxToolsthatareavailable(oreasilyinstallable)onmostinstallationsGoalistobeefficientandeffectiveratherthantobean"expert"Benefits:savetime,efficientforsystem,long-termpaybackWedonotcover:Sysadmin,security,networking4SlidesandpracticedatafordownloadSlidesandtwotextfilesavailableforpracticehttps://code.
ornl.
gov/km0/lisa19states.
txtTabulardatawithfivecolumnsprose.
txtProsewithsentencesandparagraphs5AboutYouandMeBasicexposuretoLinuxisassumedbutfeelfreetointerruptandaskquestionscommoncommands,basicunderstandingoffilesanddirectories,editingetc.
AboutMeLinuxEngineeratOakRidgeNationalLaboratoryCommandlineenthusiast6part2:Basics7backtotocwelcometotheschoolofcommandlinewizardry!
AnatomyofaTypicalCommandls-lh/etc|grep'conf'8commandargumentpipeoptionscommandKnowtheSystemid:knowyourselfw:whoisloggedin(-ftofindwheretheyarelogginginfrom)lsblk:listblockstoragedeviceslscpu:displayinfoabouttheCPUslstopo:displayhardwaretopology(needhwloc,hwloc-guipackages)free:freeandusedmemory(tryfree-g)lsb_release:distributioninfo(try-a)PS0:Usectrl-ctokillstuckcommandsorlongrunningonesPS1:Somecommandsmaynotbeavailable:whichtoverify9KnowtheProcessesListtheprocessesbyname,pidetc:ps(commonlyusedflags:aux)psimplementations:POSIX,GNUandBSD!
implementationsdifferinbehaviordeterminedbystyleofoptions:POSIX(-),GNU(--),BSD(nodash)beforeoptionsDisplayprocesses:top,htop,atopBeniceandflyundertheradar,eg.
:nice-n19tarcvzfarchive.
tgzlarge_dirKillaprocess:killtokillzombieprocesseshungsessions10ManywaystogethelpmannanoManualpagesOrganizedsection-wise--onepageforeachsection(ifexists)wget--helpHandyforquicksyntaxreferenceinfocurlModernBrowse/usr/share/docUsuallyaREADMEfilehasinfoandexamplesBrowsewithaweb-browser11WorkingwithFilescatforrelativelyshortfilescatstates.
txtlessismorethanmoreforlongfilesless/etc/ntp.
conftail-ftowatchafilegrowingliveWhatcanyoudoaboutbinaryfiles(notmuch)stringswillprinttheprintablestringsoffileodwillprintfileinoctalformatcmpwillcomparethembytebybyteComparetextfileswithcommsortedfileslinebylinediffdifferenceslinebyline--usedmostfrequently,richoptionsset,seeman12Internetoncommandlinecurliscommonlyusedascommandtodownloadfromtheweb:curl-Ohttp://www.
gutenberg.
org/files/4300/4300-0.
txtcurlifconfig.
me#quicklyfindmyIPwgetissimilar:wgethttp://www.
gutenberg.
org/files/4300/4300-0.
txtwgethttps://kubernetespodcast.
com/episodes/KPfGep{001.
.
062}.
mp3lynxcanbeausefultext-basedbrowser:avoidpeskyadswheninternetisslow/onlycareabouttexteg.
lynxtext.
npr.
orgreadlocalhtmlpages,eg.
thosefoundin/usr/share/docw3mandlinksareothertext-basedbrowsers13Beacommandlineninja:Navigation14kubectlsetsubjectrolebindingadmin--user=ldf--group=nsedcursorctrl-ectrl-a/ctrl-xxalt-falt-bMACusers:terminalpref>profile>keyboardsettings>Useoptionasmetakeyctrl-alt-]movescursorto1stoccurrenceoftoleftctrl-]movescursorto1stoccurrenceoftorightBeacommandlineninja:Deletion15kubectlget-otemplatepod/web-pod-13je7--template={{.
status.
phase}}cursorctrl-kctrl-uctrl-walt-dusectrl-ytopastebackthedeletedwildcards:charactersthatexpandatruntime*anynumberofcharacters:ls-lh/etc/*.
confexpandstoonecharacter:ls-ldNegation(!
)eg.
ls-ld[!
0-9]*Escapingandquoting\forescapingawildcard'forquotingawildcard16preventexpansionQuickandUsefulTricks!
!
repeatsthelastcommand!
$changecommandkeeplastargument:catstates.
txt#filetoolongtofitscreenless!
$#reopenitwithless!
*changecommandkeepallarguments:headstates.
txt|grep'^Al'#shouldbetailtail!
*#noneedtotypetherestofthecommandalt-.
#pastelastargumentofpreviouscommandalt--alt-.
#pastenthargumentofpreviouscommand17MoreTricks>x.
txt#createanemptyfile/"zero"alargefilecmd#tagtotagahardtoremembercommandctrl-l#clearterminalcd-#changetopreviousdircd#changetohomedirctrl-r#recallfromhistoryctrl-d#logoutfromterminal18Part3:Streams,pipeandredirection19backtotocIamsureagardenerdesignedthem!
TerminalI/OStreamsandRedirection20ThreeI/Ostreamsonterminal:standardinput(stdin),standardoutput(stdout)andstandarderror(stderr)Representedby"filedescriptors"(thinkofthemasids):0forstdin,1forstdout,2forstderrAnglebracketsareusedforredirectionto/fromcommands:>tosendtoastream>toappendtoastreamout.
txt2>err.
txt21commandsendstderrsendMoreRedirectionExamplesSendstdoutandstderrtosamefile:pipinstallrtv>stdouterr.
txt2>&1ac-pd&>stdouterr.
txt#shortform(bashv4+)Disregardbothstdoutandstderr:wgetimgs.
xkcd.
com/comics/command_line_fu.
png&>/dev/nullReadfromstdinasoutputofacommanddiff>yum_update.
log22Thepipe:runsecondcommandusingoutputoffirst!
ApipeisaLinuxconceptthatautomatesredirectingtheoutputofonecommandasinputtoanextcommand.
Useofpipeleadstopowerfulcombinationsofindependentcommands.
eg.
:find.
|less#readlonglistoffilespagewiseheadprose.
txt|grep-i'little'echo$PATH|tr':''\n'#translate:tonewlinehistory|tail#last10commandsfree-m|grepMem:|awk'{print$4}'#availablememorydu-s*|sort-n|tail#10biggestfiles/dirsinpwd23Demystifyinganddebuggingpipedcommandsfree-m|grepMem:|awk'{print$4}'isequivalenttorunningthefollowing4commands:free-m>tmp1.
txtgrepMem:tmp1.
txt>tmp2.
txtawk'{print$4}'tmp2.
txtrmtmp1.
txttmp2.
txtReducingthepipedstagesisoftenefficientandeasiertodebug.
Forinstance,theabovepipelinemaybereducedlikeso:free-m|awk'/Mem:/{print$4}'#moreonawklater24Morepipeexamples25#getpdfofamanpageman-tdiff|ps2pdf-diffhelp.
pdf#gettoday'sfilesls-al--time-style=+%D|grep`date+%D`#top10mostfrequentlyusedcommandshistory|awk'{a[$2]++}END{for(iina){printa[i]""i}}'|sort-rn|headCommandsthatonlyacceptliteralargsMostcommandsreceiveinputfromstdin(so,pipe)andfile,eg.
wcerrors.
txt"29*Fromthegnuparallel2018bookathttps://doi.
org/10.
5281/zenodo.
1146014Part4:ClassicTools:find,grep,awk,sed30backtotoctheevergreensfind:searchfilesbasedoncriteriafind/opt-name"README*"-execwc-l{}+31pathcriteria(optional)action(optional)spaceFeaturesoffindpath:mayhavemultiplepaths,eg.
find/usr/opt-iname"*.
so"criteria-name,-iname,-type(f,d,l),-inum-user,-group,-perm(ugo)-size+x[c],-empty,-newer-atime+x,-amin+x,-mmin-x,-mtime-xcriteriamaybecombinedwithlogicaland(-a)andor(-o)action-print:defaultaction,display-ls:runls-lidscommandoneachresultingfile-execcmd:executecommand-okcmdlikeexecexceptthatcommandexecutedafteruserconfirmation32findExamplesfind.
-typef-name"*.
txt"#alltextfilesincurrentdirfind.
-maxdepth1#equivalenttolsfind.
/somedir-typef-size+512M-print#allfileslargerthan512Min.
/somedirfind.
\(-name"*.
c"-o-name"*.
h"\)#allfilesthathaveeither.
cor.
hextension33grep:Searchforpatternsintextgreporiginallywasacommand"globalregularexpressionprint"or'g/re/p'intheedtexteditorItwassousefulthataseparateutilitycalledgrepwasdevelopedgrepwillfetchlinesfromatextthathasamatchforaspecificpatternUsefultofindlineswithaspecificpatterninalargebodyoftext,eg.
:lookforaprocessinalistofprocessesspotcheckalargenumberoffilesforoccurrenceofapatternexcludesometextfromalargebodyoftext34Anatomyofgrepgrep-i-n'col'states.
txt35optionsregularexpressioninputfileUsefulgrepOptions-i:ignorecase-n:displaylinenumbersalongwithlines-v:printinverseie.
linesthatdonotmatchtheregularexpression-c:printacountoflinesofmatches-A:includenlinesafterthematch-B:includenlinesbeforethematch-o:printonlythematchedexpression(notthewholeline)-E:allows"extended"regularexpressionsthatincludes(morelater)36RegularExpressionsAregularexpression(regex)isanexpressionthatmatchesapattern.
Examplepattern.
.
.
.
.
.
.
.
regex:ènomatchregex:èonematchè"Linuxisfun.
"regex:ètwomatchesè"Linuxisfun.
"and"Soismusic.
"regex:èonematchè"Soismusic.
"regex:èonematchè"Soismusic.
"37fu^Linuxisfun.
$^Soismusic.
$^Trafficnotsomuch.
$nbaris^Soic.
$RegularExpressions-contd.
.
isaSpecialcharacter;willmatchanycharacter(exceptnewline)Characterclass:oneoftheitemsinthe[]willmatch,sequencesallowed'[Cc]at'willmatchCatandcat'[f-h]ate'willmatchfate,gate,hate'b[^eo]at'willmatchbratbutnotboatorbeatExtendedregularexpressions(usewithegreporgrep-E)'*'matcheszeroormore,'+'matchesoneormore,''matcheszerooroneoccurrenceofthepreviouscharacter'|'isadelimiterformultiplepatterns,'('and')'letyougrouppatterns{}maybeusedtospecifyarepetitionrange38grepExamplesLinesthatendwithtwovowels:grep'[aeiou][aeiou]$'prose.
txtCheck5linesbeforeandafterthelinewhereterm'little'occurs:grep-A5-B5'little'prose.
txtCommentcommandsandsearchlaterfromhistorysome-hard'to'\remember--complex=command#successhistory|grep'#success'find+grepisoneveryusefulcombinationfind.
-iname"*.
py"-execgrep'add[_-]item'{}+39awk:ExtractandManipulateDataAprogrammablefilterthatreadsandprocessesinputlinebylineRichbuilt-infeatures:explicitfields($1.
.
.
$NF)&recordsmanagementfunctions(math,stringmanipulation,etc.
)regularexpressionsparsingandfilteringFeatureslikevariables,loops,conditionals,associativearrays,user-definedfunctions40Highlyrecommendedbook:TheawkprogramminglanguagebyAho,KernighanandWeinberger,ia802309.
us.
archive.
org/25/items/pdfy-MgN0H1joIoDVoIC7/The_AWK_Programming_Language.
pdfAnatomyofanawkprogram41BEGIN{actions}#runonetimebeforeinputdataisread/patternorcondition/{actions}#runforeachlineofinputEND{actions}#runonetimeafterinputprocessingAtleastoneoftheBEGIN,/patternorcondition/,{},ENDsectionneededOftenusedasone-lineidiomoftheform:awk'awk_prog'file.
txtORcommand|awk'awk_prog'whereawk_progis:awkpatternsandactionsApatternisaregexthatmatches(ornot)toaninputline,eg.
/New/#anylinethatcontains'New'/^[0-9]+/#beginningwithnumbers/(POST|PUT|DELETE)/#hasspecificwordsAnactionisasequenceofops,eg.
{print$1,$NF}#printfirstandlastfield/col{printlog($2)}#getlogofsecondfield/col{for(i=1;i0prose.
txt#skipblanklinesawk'{printNF,$0}'states.
txt#numfieldsawk'{printlength($0)}'states.
txt#numcharsawk'BEGIN{printsubstr("NewYork",5)}'#York43sed:parseandtransformtextsedisastreameditorLooksforapatternintextandapplieschanges(edits)tothemAbatchornon-interactiveeditorReadsfromfileorstdin(so,pipesaregood)onelineatatimeTheoriginalinputfileisunchanged(sedisalsoafilter),resultsaresenttostandardoutputMostfrequentlyusedidiomisfortextsubstitution44Anatomyofsedsed's/New/Old/g'states.
txt45deliminputfileregexreplacemodifiercommandOptionsaddress:maybealinenumberorarange,defaultstowholefilecommand:s:substitute,p:print,d:delete,a:append,i:insert,q:quitregex:Aregularexpressiondelimiter:Doesnothavetobe/,canbe|or:oranyothercharactermodifier:maybeanumbernwhichmeansapplythecommandtonthoccurrence,gmeansapplygloballyinthelineCommonsedflags:-n(noprint),-e(multipleops),-f(readsedfromfile),-i(inplaceedit[careful])46UsefulsedExamplessed-n'5,9p'states.
txt#printlines5through9sed-n'$p'states.
txt#printlastlinesed'1,3d'states.
txt#deletefirst3linessed'/^$/d'states.
txt#deleteallblanklinessed'/York/!
s/New/Old/'states.
txt#substituteexceptYorkkubectl-nkube-systemgetconfigmap/kube-dns-oyaml|sed's/8.
8.
8.
8/1.
1.
1.
1/'|kubectlreplace-f-47Part5:SessionManagement:tmux48backtotocforwhenthenetworkgoesdownonmyworld-savingprojectWorkspaceManagementwithtmuxtmux(v1.
8)isaterminalmultiplexerthatletsyoucreatemultiple,persistentterminalswithinoneloginInotherwordstmuxisaprogramwhichallowsyoutohavepersistentmultiple"tabs"inasingleterminalwindow.
Usefulwheneg.
acompilationorotheroperationwilltakealongtimeforinteractivemultitaskingforexoticstuffsuchaspairprogramming49AShorttmuxTutorialTypicaltmuxworkflowtmuxnew-smysession#startanewsession#runanycommandsasnormalctrl-b:detach#detachthesession,logout,gohome#later,loginagaintmuxa-tmysession#getthesamesessionbackOtherusefultmuxcommandsctrl-b(#switchtoprevioussessionctrl-b)#switchtonextsessiontmuxls#listallsessionstmuxkill-session-tmysession#killasession50Livecollaborationwithtmux#user1#tmux-S/tmp/collabchmod777/tmp/collab#user2#tmux-S/tmp/collabattach51CreatePanesandSynchronizewithtmuxtmux#startatmuxsessionctrl-b"#splithorizontallyctrl-b%#splitverticallyctrl-b:setwsynchronize-paneson#synchronized#ctrl-b:setwsynchronize-panesoffctrl-bo#movethroughthepanesctrl-bx#killtheactivepane52Part6:ssh:configandtunneling53backtotocbuildsecuretunnelssshconfig(~/.
ssh/config)HostsummitPort22hostnamesummit.
olcf.
ornl.
govUserketan2ServerAliveCountMax=3#maxnumofalivemessagessentwithoutackServerAliveInterval=15#sendanullmessageevery15secHostcadesPort22hostnameor-condo-login.
ornl.
govUserkm0ServerAliveCountMax=3ServerAliveInterval=15#nowtossh/scptocades,justneed"ssh/scpcades"54BenefitsofsshconfigMakessshcommandseasiertorememberincaseofmultiplehostsCustomizesconnectiontoindividualhostsFormore,seeman5ssh_configForexample:sshsummitissufficienttoconnecttosummit.
olcf.
ornl.
govwithallthepropertiesmentionedinthesection:HostsummitPort22hostnamesummit.
olcf.
ornl.
govUserketan2ServerAliveCountMax=3ServerAliveInterval=1555PortforwardoverSSHTunnel*lclhost$ssh-Llport:host:hportremotehost-N56localsshcommandlocalport"hostname"onremotehostportonremotehostremotehostnocommand*simplestformSSHTunnelingExampleRunanHTTPserveronremotenodeandbrowsethroughlocalwebbrowser:step1.
remote$python2-mSimpleHTTPServer25000ORstep1.
remote$python3-mhttp.
server25000step2.
local$ssh-L8000:localhost:25000id@remote-Nstep3.
Openbrowseronlocalandnavigatetohttp://localhost:800057part7:BashTools58backtotocForwhenthat'helloworld'becomesaprojectBashShellBasicsCommandsandutilitiessuchasgrep,sed,awkmaybeinvokedVariables,constants,conditionals,loopsandfunctionsmaybedefinedArithmeticoperationsavailableLogicaloperations&&(AND)and||(OR)available:wget.
.
.
||curl.
.
.
:runcurliffwgetfailsmakeinstall&&maketest:testiffinstallsucceedsShell"Startup"filessetenvironmentasyoustartyourshell.
bashrc:afilethatrunsineachnewshellthatisspawned.
bash_profile:afilethatrunsonlyina"loginshell"(andnotallshellseg.
itwon'trunifyouinvokeashellscriptthatcreatesasubshell)59AliasesandFunctionsAliasesareshortandconvenientnamesforlongcommandsTheyareusuallydefinedin.
bashrcoraseparate.
aliasesfileTotemporarilybypassanalias(saywealiasedlstols-a),use\:\lsBashfunctionsareusuallydefinedin.
bashrc/.
bash_profileFunctionsaremoreexpressiveandpreferredoveraliases60Examplesofusefulaliasesaliass=sshaliasc=clearaliascx='chmod+x'aliasls='ls-thor'aliasmore=lessaliasps='psauxf'aliaspsg='psaux|grep-vgrep|grep-i-eUSER-e'alias.
.
='cd.
.
'aliasmyp='ps-fjH-u$USER'aliascleanup='rm-f*.
tmp*.
aux*.
log'61ExamplesofusefulFunctionsmcd(){mkdir-p$1;cd$1}cdl(){cd$1;ls}backup(){cp"$1"{,.
bak};}#testfirstgfind(){find/-iname$@2>/dev/null}lfind(){find.
-iname$@2>/dev/null}rtfm(){help$@||man$@||$BROWSER"http://www.
google.
com/searchq=$@";}See/usr/share/doc/bash-*/examples/functionsformorefunctionexamples62VariablesandCommandSubstitutionVariablesareimplicitlytypedMaybealiteralvalueorcommandsubstitutevname=value#assignvaluetovariablevname$vname#readvalueofvariablevnameCommandsubstitution:curdir=$(PWD)curdate=$(date+%F)echo"Thereare$(ls-1|wc-l)itemsinthecurrentdir"63#!
/bin/shmsg="HelloWorld"echo$msgConditionalsif-then-elseconstructtobranchsimilartoprogramminglanguagesTwoformsofconditionalevaluationmechanisms:testand[…]$iftest$USER='km0';thenecho'Iknowyou';elseecho'Whoareyou';fi$if[-f/etc/yum.
conf];thenecho'yum.
confexists';elseecho'filedonotexist';fi64Conditionalssummarystring-zstring:lengthofstring0-nstring:lengthofstringnot0string1=string2:stringsareidentical(noteasingle=)numericint1-eqint2:firstintequaltosecond-ne,-gt,-ge,-lt,-le:not-equal,greater-than,-greater-or-equal.
.
.
file-rfilename:fileexistsandisreadable-wfilename:fileexistsandiswritable-f,-d,-s:regularfile,directory,existsandnotemptylogic!
,-a,-o:negate,logicaland,logicalor65LoopsBasicstructure(threeforms):foriin{0.
.
9};doecho$i;donefor((i=0;iUsesofheredocMultilinemessageusingcatUsevariablestoplugintocreatedfiles,egtestmultipleconfigurationsforaprogram67catinstall.
yml----hosts:$iENDansible-playbookinstall.
yml--check>out"$i".
txtdonepart8:MiscellaneousUtilities68backtotochandylikemidnightsnackGetthingsdoneatspecifictimeswithatatwillexecutethedesiredcommandonaspecificdayandtimeat17:00#pressenterat>log_days_activities.
sh#smtimesnoat>prompt[ctrl-d]atofferskeywordssuchasnow,noon,today,tomorrowofferstermssuchashours,daystobeusedwiththe+symbolatnoonatnow+1yearat3:08pm+1dayat15:01December19,201869GetthingsdoneperiodicallywithcroncronwillexecutethedesiredcommandperiodicallyAcrontabfilecontrolsandspecifieswhattoexecutewhenAnentrymaybecreatedinanyfileandaddedtosystemwiththecrontabcommandlikeso:echo'1518306*find/home-mtime+30-print'>f00crontabf00#addabovetosystemcrontabcrontab-l#listcrontabentriescrontab-r#removecrontabentriesOutputofthecron'dcommandwillbeinmail(alternativelyitmayberedirectedtoafilewith'>')Whatdoestheentriesinacrontabmeanthough(seenextslide)70Anatomyofacrontabentry1518306*find/home-mtime+30-print71dayofmonth(0-max)hours(0-23)dayofweek(Sun=0)month(Jan=1)mins(0-59)commandtobeexecutedRunthefindcommandonJune30ofeveryyearat6:15PMnomatterwhatdayofweekitis.
MathGeneraterandomnumberusingshuf(mayneedtoinstall)shuf-i1-100-n1Formatnumberswithnumfmtnumfmt--to=si10001.
0Knumfmt--from=iec1K1024bcisaversatilecalculatorbctestfile.
txtCreatepdffromtextusingvim:vimstates.
txt-c"hardcopy>states.
ps|q"&&ps2pdfstates.
ps#convertpstopdf74Randomstuff-2Runacommandasadifferentgroupsggrpgit-c'gitpush'Displayacsvincolumnar/tabularformatcolumn-t-s,filename.
csvGeneratepasswordhead/dev/urandom|tr-dcA-Za-z0-9|head-c8opensslrand8-base64|cut-c1-8pwgen#maynotbeavailablebydefault75SummaryLinuxcommand-lineenvironmentpowerfulifexploitedwellPipesandredirectionkeyLinuxcontributionsRewardingintheshort-termaswellaslong-termClassicalandmoderntoolswellsuitedformodern-styleusagePractice!
Sendcomments,feedback,questions:km0@ornl.
gov76backtotocCredits,referencesandresourcesTheman,infoanddocpagesbash:gnu.
org/software/bash/manual/bashref.
htmlgrep:gnu.
org/software/grep/manual/grep.
htmlsed:catonmat.
net/blog/worlds-best-introduction-to-sedawk:ferd.
ca/awk-in-20-minutes.
htmltmux:gist.
github.
com/MohamedAlaa/2961058wikipediaarticles:unix,linux,Bash_(Unix_shell)commandlinefu.
com77Wheretogofromheregithub.
com/jlevy/the-art-of-command-linejeroenjanssens.
com/2013/08/16/quickly-navigate-your-filesystem-from-the-command-line.
htmllinux.
byexamples.
com/archives/42/command-line-calculator-bccatonmat.
net/blog/bash-one-liners-explained-part-threewiki.
bash-hackers.
orghttps://gist.
github.
com/MohamedAlaa/2961058#file-tmux-cheatsheet-markdownwizardzines.
comhttps://crontab.
guruleimao.
github.
io/blog/Tmux-Tutorialunix.
stackexchange.
comdanyspin97.
org/blog/makefiles-best-practices78ThankyouforyourtimeandattentionQuestions79PracticeandExercisesCreatethreetmuxsessions:s1,s2ands3;detachthemListtheactivesessionswithtmuxlsKilltheactivesessionswithtmuxkill-session-tCanyoukillthemallwithonecommandhint:usexargsinapipeCreateatmuxsessionandsplitthescreeninto4panesverticallyandhorizontallySetitsothatallpanesaresynchronized.
Testwithanycommand.
80PracticeandExercisesUseyourfavoriteeditortoedit.
bashrcand.
bash_profile--addaline:echo'Iambashrc'to.
bashrcaddaline:echo'Iambash_profile'to.
bash_profileCloseandreopenterminal,whatdoyouseeWithinterminaltype/bin/bash,whatdoyouseeCreateacopyofprose.
txtusingcpprose.
txttmp.
txt;makesmallchangetotmp.
txtandcompareprose.
txtandtmp.
txtwithcmp,commanddiffDeletethoselinesfrom.
bashrcand.
bash_profilewhendoneThecharacterclass[[:class:]]maybeusedaswildcard:classmaybealpha,alnum,ascii,digit,upper,lower,punct,word;tryls/etc/[[:upper:]]*81PracticeandExercisesListallconffilesin/etcyouhaveaccessto,redirectstderrto/dev/nullBuildasoftwareandcollecterrorsandoutputinseparatefiles,fillinthe__makeall__std.
out__>std.
errRuncmakecommandandgatheralllogsinasinglefileinbackgroundcmakecmake.
log__#bashv4andaboveSameasaboveinlongformatmpirun-np8.
/a.
out__outerr.
txt2>__182PracticeandExercisesSimplifythefollowingcommandline:TOKEN=$(kubectldescribesecret-nkube-system$(kubectlgetsecrets-nkube-system|grepdefault|cut-f1-d'')|grep-E'^token'|cut-f2-d':'|tr-d'\t'|tr-d"")ReplacethecutcommandswithawkcommandsAccommodatethegrepwiththeawkAccommodatethetwotrcommandswithinawkcommands(hint:useawk'sgsubbuilt-infunction)83PracticeandExercisesCreateafiletitledthewordsthatstartwithletter'C'(fillthe__):grep-i'^c'states.
txt|awk'{print$4}'|__touchRemovetemporaryfiles:find.
–iname'*.
tmp'|__rm#okCreateadirectoryforallrunningprocessesps|awk'NR!
=1{print$4}'|mkdir#NOTOKps|awk'NR!
=1{print$4}'|__mkdir#ok84PracticeandExercisesUsesedtoprintlines11-15ofstates.
txtFillupthe__inthefollowingfindcommands__.
-typed-perm777-execchmod755{}+find.
-type__-name"*.
tmp"-execrm-f{}+find__-atime+50#filescrontabentry:3021***find/tmp/usr/tmp-atime+30-execrm-f{}+Frameanatcommandtorunthedatecommandtomorrowat8p.
m.
writeashellscripttofindalltheprimenumbersbetween1000and10000hints:usefor,if,factor,wc88AlternativelocationforSlidesandDatahttps://github.
com/ketancmaheshwari/lisa1989