How do I access environment variables in Python? - Stack ...

Environment variables are accessed through os.environ import os print(os.environ['HOME']). Or you can see a list of all the environment variables using: Home Public Questions Tags Users Companies Collectives ExploreCollectives Teams StackOverflowforTeams –Startcollaboratingandsharingorganizationalknowledge. CreateafreeTeam WhyTeams? Teams CreatefreeTeam CollectivesonStackOverflow Findcentralized,trustedcontentandcollaboratearoundthetechnologiesyouusemost. Learnmore Teams Q&Aforwork Connectandshareknowledgewithinasinglelocationthatisstructuredandeasytosearch. Learnmore HowdoIaccessenvironmentvariablesinPython? AskQuestion Asked 11years,2monthsago Modified 29daysago Viewed 2.4mtimes 2749 362 HowdoIgetthevalueofanenvironmentvariableinPython? pythonenvironment-variables Share Improvethisquestion Follow editedApr1at12:14 MateenUlhaq 21.2k1616goldbadges7979silverbadges123123bronzebadges askedFeb5,2011at13:03 AmitYadavAmitYadav 28.5k66goldbadges4040silverbadges5252bronzebadges 0 Addacomment  |  15Answers 15 Sortedby: Resettodefault Highestscore(default) Datemodified(newestfirst) Datecreated(oldestfirst) Helpusimproveouranswers.Aretheanswersbelowsortedinawaythatputsthebestansweratornearthetop? Takeashortsurvey I’mnotinterested 4003 Environmentvariablesareaccessedthroughos.environ importos print(os.environ['HOME']) Oryoucanseealistofalltheenvironmentvariablesusing: os.environ Assometimesyoumightneedtoseeacompletelist! #usinggetwillreturn`None`ifakeyisnotpresentratherthanraisea`KeyError` print(os.environ.get('KEY_THAT_MIGHT_EXIST')) #os.getenvisequivalent,andcanalsogiveadefaultvalueinsteadof`None` print(os.getenv('KEY_THAT_MIGHT_EXIST',default_value)) ThePythondefaultinstallationlocationonWindowsisC:\Python.Ifyouwanttofindoutwhilerunningpythonyoucando: importsys print(sys.prefix) Share Improvethisanswer Follow editedJul25,2021at20:57 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredFeb5,2011at13:18 RodRod 47.9k33goldbadges3434silverbadges5252bronzebadges 11 1 hellorod,thanksforyoureffectivereplyconcerning'default-installation';effectiveinpointofviewtounderstanditquicklyratherthangothroughthelinks.That’sreallyIappreciated:)butaboutmy(1)questionpleaselookatthecommandandoutputssnippetbelow:>>>importos>>>printos.environ['PYTHONPATH']Traceback(mostrecentcalllast):File"",line1,inFile"C:\Python25\lib\os.py",line435,ingetitemreturnself.data[key.upper()]KeyError:'PYTHONPATH'>>>printos.environ.get('PYTHONPATH')None>>>//PLZtobecontinue...// – AmitYadav Feb5,2011at14:47 Ina1stwayscriptisthrowingExceptionwhereaswith2ndonegivingNone.So,isthereanywaytogetitmeaningfulvalueoramIdoinginawrongway???Amit. – AmitYadav Feb5,2011at14:49 9 os.environisadictionary.TryingtoaccessakeynotpresentinthedictionarywillthrowaKeyError.ThegetmethodsimplyreturnsNonewhenthekeydoesnotexists.DoyouhavePYTHONPATHset?CanyoutrywithavariablesuchasPATH,thatisguaranteedtoexist?Doesitreturnameaningfulvalue? – Rod Feb5,2011at19:21 2 PYTHONPATHisusedtoaddnewsearchpathtoPython(sys.path)fromoutsidePython.Havealookatdocs.python.org/using/cmdline.html#environment-variables – Rod Feb7,2011at14:41 31 .get()canalsobegivenadefault. – GringoSuave Sep21,2018at15:25  |  Show6morecomments 311 Tocheckifthekeyexists(returnsTrueorFalse) 'HOME'inos.environ Youcanalsouseget()whenprintingthekey;usefulifyouwanttouseadefault. print(os.environ.get('HOME','/home/username/')) where/home/username/isthedefault Share Improvethisanswer Follow editedDec10,2018at2:15 BorisV 10.4k77goldbadges7676silverbadges7979bronzebadges answeredJul12,2012at8:14 lgriffithslgriffiths 3,25511goldbadge1212silverbadges77bronzebadges 3 4 Whichisbetter,"HOME"inos.environoros.environ.get('HOME')? – endolith Feb3,2017at16:11 14 @endolithTheydodifferentthings.ThefirstreturnsTrueorFalse,whilethesecondreturnsavalue,possiblyNone. – Trenton Feb13,2018at22:38 3 @endolith,thecorrectquestionwoudbe"HOME"inos.environvsos.environ.get('HOME')isNone.Asyoucanseefirstisfarmorereadable&comfortabletoworkwith. – KonstantinSekeresh Oct16,2019at13:43 Addacomment  |  74 Theoriginalquestion(firstpart)was"howtocheckenvironmentvariablesinPython." Here'showtocheckif$FOOisset: try: os.environ["FOO"] exceptKeyError: print"PleasesettheenvironmentvariableFOO" sys.exit(1) Share Improvethisanswer Follow answeredMar29,2012at13:58 ScottCWilsonScottCWilson 17.7k1010goldbadges5757silverbadges8080bronzebadges 2 5 Trycanbefaster.Thecaseofenvvarsislikelybestfor'try':stackoverflow.com/a/1835844/187769 – RandomInsano Feb5,2017at16:49 22 @RandomInsanofaster=/=better.Thiscodelookslessreadablethanan"if'FOO'notinos.environ:..."block – Dangercrow Oct13,2017at13:27 Addacomment  |  69 Actuallyitcanbedonethisway: importos foritem,valueinos.environ.items(): print('{}:{}'.format(item,value)) Orsimply: fori,jinos.environ.items(): print(i,j) Forviewingthevalueintheparameter: print(os.environ['HOME']) Or: print(os.environ.get('HOME')) Tosetthevalue: os.environ['HOME']='/new/value' Share Improvethisanswer Follow editedJul25,2021at21:03 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredMar10,2018at15:52 britodfbrbritodfbr 1,4551212silverbadges1616bronzebadges 6 8 No,thisanswerreallydoesn'taddanythingontopoftheexistinganswers – Bart May2,2018at10:06 2 Thisshouldberemoved,itisaduplicateofotheranswers.str.formatisjustafancyaddition. – miike3459 Apr21,2019at16:46 >>>importos,pprint;pprint.pprint(list(os.environ.items())) – noobninja May10,2020at18:41 1 Thefirstanswerwithreadableoutputfortheentireenv,thanks.ToviewtheenvinthePyCharmdebugger,Ievaluate{k:vfork,vinsorted(os.environ.items())} – Noumenon Aug4,2021at22:55 itaddshowtosetthevalue – M.C. Nov26,2021at10:21  |  Show1morecomment 57 Youcanaccesstheenvironmentvariablesusing importos printos.environ TrytoseethecontentofthePYTHONPATHorPYTHONHOMEenvironmentvariables.Maybethiswillbehelpfulforyoursecondquestion. Share Improvethisanswer Follow editedJul25,2021at20:58 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredFeb5,2011at13:07 andrei1089andrei1089 97855silverbadges88bronzebadges Addacomment  |  34 Asfortheenvironmentvariables: importos printos.environ["HOME"] Share Improvethisanswer Follow editedJul25,2021at20:58 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredFeb5,2011at13:07 JimBrissomJimBrissom 29.9k33goldbadges3535silverbadges3333bronzebadges Addacomment  |  30 importos forainos.environ: print('Var:',a,'Value:',os.getenv(a)) print("alldone") Thatwillprintalloftheenvironmentvariablesalongwiththeirvalues. Share Improvethisanswer Follow editedApr6,2017at8:35 erik.weathers 76011goldbadge77silverbadges1313bronzebadges answeredMar28,2017at15:46 AzorianAzorian 30133silverbadges22bronzebadges Addacomment  |  24 Importtheosmodule: importos Togetanenvironmentvariable: os.environ.get('Env_var') Tosetanenvironmentvariable: #Setenvironmentvariables os.environ['Env_var']='SomeValue' Share Improvethisanswer Follow editedJul25,2021at21:19 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredMay19,2021at9:22 imerlaimerla 1,41922goldbadges99silverbadges1717bronzebadges Addacomment  |  23 Ifyouareplanningtousethecodeinaproductionwebapplicationcode,usinganywebframeworklikeDjangoandFlask,useprojectslikeenvparse.Usingit,youcanreadthevalueasyourdefinedtype. fromenvparseimportenv #willreadWHITE_LIST=hello,world,hitowhite_list=["hello","world","hi"] white_list=env.list("WHITE_LIST",default=[]) #Perfectforreadingboolean DEBUG=env.bool("DEBUG",default=False) NOTE:kennethreitz'sautoenvisarecommendedtoolformakingproject-specificenvironmentvariables.Forthosewhoareusingautoenv,pleasenotetokeepthe.envfileprivate(inaccessibletopublic). Share Improvethisanswer Follow editedJul25,2021at21:02 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredJan10,2017at4:12 RenjithThankachanRenjithThankachan 3,88611goldbadge2525silverbadges4444bronzebadges Addacomment  |  14 Therearealsoanumberofgreatlibraries.Envs,forexample,willallowyoutoparseobjectsoutofyourenvironmentvariables,whichisrad.Forexample: fromenvsimportenv env('SECRET_KEY')#'your_secret_key_here' env('SERVER_NAMES',var_type='list')#['your','list','here'] Share Improvethisanswer Follow editedJul25,2021at21:04 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredDec19,2018at16:00 PeterKonnekerPeterKonneker 15311silverbadge77bronzebadges 1 1 Whatdoes"rad"meanin"whichisrad"?rad-"1.(slang)Clippingofradical;excellent" – PeterMortensen Jul25,2021at21:06 Addacomment  |  7 Youcanalsotrythis: First,installpython-decouple pipinstallpython-decouple Importitinyourfile fromdecoupleimportconfig Thengettheenvironmentvariable SECRET_KEY=config('SECRET_KEY') ReadmoreaboutthePythonlibraryhere. Share Improvethisanswer Follow editedJul25,2021at21:15 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredApr8,2020at15:20 SteveMittoSteveMitto 10311silverbadge55bronzebadges Addacomment  |  6 Edited-October2021 Following@Peter'scomment,here'showyoucantestit: main.py #!/usr/bin/envpython fromosimportenviron #Initializevariables num_of_vars=50 foriinrange(1,num_of_vars): environ[f"_BENCHMARK_{i}"]=f"BENCHMARKVALUE{i}" defstopwatch(repeat=1,autorun=True): """ Source:https://stackoverflow.com/a/68660080/5285732 stopwatchdecoratortocalculatethetotaltimeofafunction """ importtimeit importfunctools defouter_func(func): @functools.wraps(func) deftime_func(*args,**kwargs): t1=timeit.default_timer() for_inrange(repeat): r=func(*args,**kwargs) t2=timeit.default_timer() print(f"Function={func.__name__},Time={t2-t1}") returnr ifautorun: try: time_func() exceptTypeError: raiseException(f"{time_func.__name__}:autorunonlyworkswithnoparameters,youmaywanttouse@stopwatch(autorun=False)")fromNone returntime_func ifcallable(repeat): func=repeat repeat=1 returnouter_func(func) returnouter_func @stopwatch(repeat=10000) defusing_environ(): foriteminenviron: pass @stopwatch defusing_dict(repeat=10000): env_vars_dict=dict(environ) foriteminenv_vars_dict: pass python"main.py" #Output Function=using_environ,Time=0.216224731 Function=using_dict,Time=0.00014206099999999888 Ifthisistrue...It's1500xfastertouseadict()insteadofaccessingenvirondirectly. Aperformance-drivenapproach-callingenvironisexpensive,soit'sbettertocallitonceandsaveittoadictionary.Fullexample: fromosimportenviron #Slower print(environ["USER"],environ["NAME"]) #Faster env_dict=dict(environ) print(env_dict["USER"],env_dict["NAME"]) P.S-ifyouworryaboutexposingprivateenvironmentvariables,thensanitizeenv_dictaftertheassignment. Share Improvethisanswer Follow editedOct1,2021at16:10 answeredJan15,2021at0:39 MeirGabayMeirGabay 2,08211goldbadge2020silverbadges2828bronzebadges 1 Thankyou,Peter,I'veupdatedmyanswer – MeirGabay Oct1,2021at16:11 Addacomment  |  4 ForDjango,seeDjango-environ. $pipinstalldjango-environ importenviron env=environ.Env( #setcasting,defaultvalue DEBUG=(bool,False) ) #reading.envfile environ.Env.read_env() #Falseifnotinos.environ DEBUG=env('DEBUG') #RaisesDjango'sImproperlyConfiguredexceptionifSECRET_KEYnotinos.environ SECRET_KEY=env('SECRET_KEY') Share Improvethisanswer Follow editedJul25,2021at21:08 PeterMortensen 29.9k2121goldbadges9999silverbadges124124bronzebadges answeredNov20,2019at15:36 LeonardoLeonardo 19411silverbadge55bronzebadges 1 1 Anexplanationwouldbeinorder.Whatisthecontext-inwhatcontextisthecodeexecuted?OnaserverwithDjango?Locallyfortestingitout?Somewhereelse?Whatistheidea?Whatisthecodesupposedtoaccomplish? – PeterMortensen Jul25,2021at21:11 Addacomment  |  1 Youshouldfirstimportosusing importos andthenactuallyprinttheenvironmentvariablevalue print(os.environ['yourvariable']) ofcourse,replaceyourvariableasthevariableyouwanttoaccess. Share Improvethisanswer Follow answeredMar14,2021at6:41 ichirodichirod 16511silverbadge33bronzebadges Addacomment  |  1 Thetrickypartofusingnestedfor-loopsinone-linersisthatyouhavetouselistcomprehension.Soinordertoprintallyourenvironmentvariables,withouthavingtoimportaforeignlibrary,youcanuse: python-c"importos;L=[f'{k}={v}'fork,vinos.environ.items()];print('\n'.join(L))" Share Improvethisanswer Follow answeredDec29,2021at20:54 not2qubitnot2qubit 11.8k77goldbadges8282silverbadges110110bronzebadges Addacomment  |  Highlyactivequestion.Earn10reputation(notcountingtheassociationbonus)inordertoanswerthisquestion.Thereputationrequirementhelpsprotectthisquestionfromspamandnon-answeractivity. Nottheansweryou'relookingfor?Browseotherquestionstaggedpythonenvironment-variablesoraskyourownquestion. TheOverflowBlog Agilitystartswithtrust WouldyoutrustanAItobeyoureyes?(Ep.437) FeaturedonMeta HowmighttheStagingGround&thenewAskWizardworkontheStackExchange... Shouldweburninatethe[qa]tag? 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