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
Really Good One to Watch
The daughter takes a step forward with each question.
The father stands there. The daughter, who starts off playfully laughing.... is shocked to see her father standing there despite her progress.
When the father steps forward for the final question, she hugs him. Father - Daughter ❤️
Children can be raised without knowing hardship.
But it is important to make them know that nothing they get comes so easily ❤️
#Inspiring
@InspiringThoughts
Really Good One to Watch
The daughter takes a step forward with each question.
The father stands there. The daughter, who starts off playfully laughing.... is shocked to see her father standing there despite her progress.
When the father steps forward for the final question, she hugs him. Father - Daughter ❤️
Children can be raised without knowing hardship.
But it is important to make them know that nothing they get comes so easily ❤️
#Inspiring
@InspiringThoughts
Really Good One to Watch
The daughter takes a step forward with each question.
The father stands there. The daughter, who starts off playfully laughing.... is shocked to see her father standing there despite her progress.
When the father steps forward for the final question, she hugs him. Father - Daughter ❤️
Children can be raised without knowing hardship.
But it is important to make them know that nothing they get comes so easily ❤️
#Inspiring
@InspiringThoughts
Really Good One to Watch
The daughter takes a step forward with each question.
The father stands there. The daughter, who starts off playfully laughing.... is shocked to see her father standing there despite her progress.
When the father steps forward for the final question, she hugs him. Father - Daughter ❤️
Children can be raised without knowing hardship.
But it is important to make them know that nothing they get comes so easily ❤️
#Inspiring
@InspiringThoughts
Really Good One to Watch
The daughter takes a step forward with each question.
The father stands there. The daughter, who starts off playfully laughing.... is shocked to see her father standing there despite her progress.
When the father steps forward for the final question, she hugs him. Father - Daughter ❤️
Children can be raised without knowing hardship.
But it is important to make them know that nothing they get comes so easily ❤️
#Inspiring
@InspiringThoughts