reload_flag=""
if [[ -n "${DEBUG}" ]]; then
reload_flag="--reload"
fi
if [[ -n "${WORKER_COUNT}" ]]; then
workers=${WORKER_COUNT}
else
workers=2
fi
gunicorn --workers ${workers} \
--bind 0.0.0.0:8000 \
${reload_flag} main.wsgi
Писали такие конструкции чтобы проверить наличие флага и сформировать команду правильно?
На самом деле можно сделать тоже самое проще. Для этого используются операторы условной подстановки, доступные в оболочках семейства POSIX.
:- для установки значений по умолчанию
${WORKER_COUNT:-2}
Если переменная не объявлена, то будет дефолтное значение 2.
:+ подставляет указанный текст, если переменная не пуста
${DEBUG:+--reload}
Если что-то есть в переменной то распечатается текст после символа +, в противном случае - ничего. Удобно для опциональных флагов, как в нашем примере.
Итого наш скрипт может выглядеть так:
gunicorn --workers ${WORKER_COUNT:-2} \
--bind 0.0.0.0:8000 \
${DEBUG:+--reload} main.wsgi
Есть еще два оператора.
:= не только подставить дефолтное значение, но и присвоить его переменной, если она пуста
# никаких переменных еще нет
VAL1=${VAL2:=hello}
# теперь доступны обе
echo $VAL1 $VAL2
# hello hello
:? остановить выполнение с ошибкой, если переменной нет.
echo ${MISS:?is required}
bash: MISS: is required
Код выхода будет 1.
#tricks#linux
#Idiom
💢Go off on a tangent
Or
💢 Go off at a tangent
🔰If a person or piece of writing goes off on a tangent or goes off at a tangent, they start saying or thinking something that is not directly connected with what they were saying or thinking before
💠Note:-
In geometry, a tangent is a straight line which touches a curve at one point
🕸 Ex:- Our teacher would occasionally go off on a tangent and start talking about something totally unrelated to the textbook.
💠Note:-
You can use other verbs instead of go
🕸 Ex:- The book's theme wandersoff on a tangent now and then.
#Idiom
🕸People in society🕸
❄️A self-made man
♣️ A person who is rich and successful because they have worked hard, not because they were born into a rich family
❄️The chattering classes
♣️ Educated people who enjoy discussing social, political and cultural issues
❄️A second-class citizen
♣️ Someone is treated as if they are less important than others in society
❄️The grass roots
♣️ Ordinary people in a political or sporting organisation, not the leaders
❄️ The silent majority
♣️ A large number of people who do not express their opinions publicly
❄️ The (men in) grey suits
♣️ People in business or politics with a lot of influence or power, although they are not well known to the public
❄️Public enemy number one
♣️ Smth or someone that a lot of people dislike or disapprove of
❄️New kid on the block
♣️ Someone who is new in a place or organisation and has many things to learn about it (informal).
#Idiom
💢Even exchange: a trade of equal value; when you return something and take something else that costs the same price
✨ Ex: If you return that jacket and get this sweater instead, it will be an even exchange. They're both $39.99.
#Idiom
💢(To) steer clear of: to avoid, usually due to a bad experience
✨ Ex: Mark got food poisoning at O'Reilly's? We'd better steer clear of that place from now on!
#Idiom
💢(To) have the magic touch: to have talent at doing something; to be able to do something difficult.
✨ Ex: You can't open that bottle? Give it to Ivan. He usually has the magic touch.