Наверняка вы замечали, что в Python есть удобная функция для получения переменной окружения
os.getenv(NAME)
И её "сестра" для создания или изменения переменных окружения
os.putenv(NAME, VALUE)
Но почему-то putenv() не работает как должно. Энвайромент не обновляется!
os.putenv('MYVAR', '1')
print(os.getenv('MYVAR'))
... и ничего 😴
Почему так?
На самом деле энвайромент обновляется, но это значение не добавляется в словарь os.environ.
Откройте исходник функции os.getenv(). Это просто шорткат для os.environ.get()
В то время как putenv() это built-in С-функция.
Словарь os.environ (или точней класс из MutableMapping) создаётся из энвайромента в момент инициализации. Функция putenv() самостоятельно его не изменяет.
В тоже время, когда вы создаёте или изменяете ключ в os.environ, автоматически вызывается putenv() в методе __setitem__().
То есть, технически putenv() всё делает верно, но в os.environ это не отражается. Можно проверить так:
>>> os.putenv('MYVAR', '123')
>>> os.system('python -c "import os;print(os.getenv(\'MYVAR\'))"')
123
Я объявил переменную в текущем процессе и вызвал дочерний процесс, который её унаследовал и получил в составе os.environ.
Аналогично при удалении переменной вызывается еще одна built-in функция unsetenv(), удаляющая переменную из системы.
Итого
▫️ Удобней всего явно обновлять переменные через os.environ
▫️ Есть способ неявно создать/удалить переменную через putenv/unsetenv, что не повлияет на os.environ но изменит энвайромент и передаст изменения сабпроцессам. Но так лучше не делать!
▫️os.environ это просто обертка для built-in функций putenv() и unsetenv().
#basic
Our #Measles situation report for weeks 45, 2024 has been published.
The weekly report provides a summary of the #Measles epidemiological situation as at November 2024 and response activities in Nigeria.
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#Measles is highly infectious.
Early symptoms are high-grade fever, cough, runny nose, red eyes & tiny white spots in the mouth.
Please report immediately to a health facility when these symptoms are observed.
Read more via:
https://ncdc.gov.ng/diseases/info/M
REDNESS OF THE EYE is an early indication of #Measles when observed with symptoms like high-grade fever, running nose, dry cough & tiny spots in the mouth.
Please report immediately to a health facility when these symptoms are observed.
Visit https://ncdc.gov.ng/diseases/info/M for more information.
#Measles is highly infectious.
Early symptoms are high-grade fever, cough, runny nose, red eyes & tiny white spots in the mouth.
Please report immediately to a health facility when these symptoms are observed.
Read more via:
https://ncdc.gov.ng/diseases/info/M
Runny nose, red eyes, cough, high fever and tiny white spots in the mouth are early symptoms of #measles infection.
Seek immediate medical attention if you experience these symptoms or notice them in your loved ones.
Visit https://ncdc.gov.ng/diseases/info/M to read more
#Measles is highly contagious.
Take all persons showing symptoms of the disease to the nearest healthcare centre for accurate diagnosis and treatment.
Read more via https://ncdc.gov.ng/diseases/info/M
#Measles is an acute, highly infectious disease with initial symptoms of high-grade fever, cough, runny nose, red eyes & tiny white spots in the mouth.
Please report to a health facility immediately if you experience these symptoms.
RUNNING NOSE is an early indication of #Measles when observed with symptoms like high fever, red eyes, dry cough & tiny spots in the mouth.
Please report immediately to a health facility when these symptoms are observed.
Visit https://ncdc.gov.ng/diseases/info/M for more.
REDNESS OF THE EYE is an early indication of #Measles when observed with symptoms like high-grade fever, running nose, dry cough & tiny spots in the mouth.
Please report immediately to a health facility when these symptoms are observed.
Visit https://ncdc.gov.ng/diseases/info/M for more.
#Measles is highly contagious.
Isolate all suspected cases of the disease and take them to the nearest healthcare facility immediately.
Read more via https://ncdc.gov.ng/diseases/info/M
#Measles is an acute, highly infectious disease with initial symptoms of high fever, cough, runny nose, red eyes & tiny white spots in the mouth.
Please immediately report to a health facility if you experience these symptoms.
Read more: https://ncdc.gov.ng/diseases/info/M
#Measles is not just a rash.
Routine immunisation must remain a priority for parents and caregivers.
#TakeResponsibility to prevent the spread of such as #Measles.