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
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📞 742261078
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✨ ADC International Youth Summit 2026 ✨
We are excited to share some of the brightest moments from one of the most large-scale and inspiring events of the year — ADC International Youth Summit 2026!
This summit brought together active and ambitious youth, leaders, speakers, and experts from different countries. Throughout these productive days, participants exchanged ideas, gained new knowledge, built valuable connections, and took important steps toward their future.
We are proud of every participant and grateful to everyone who became part of this incredible event!
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📞 742261078
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✨ ADC International Youth Summit 2026 ✨
Biz yilning eng yirik va ilhomlantiruvchi tadbirlaridan biri — ADC International Youth Summit 2026’dan yorqin lahzalarni siz bilan baham ko‘rishdan mamnunmiz!
Ushbu sammit turli mamlakatlardan kelgan faol va ambitsiyali yoshlar, liderlar, spikerlar hamda ekspertlarni birlashtirdi. Mazmunli kunlar davomida ishtirokchilar fikr almashdilar, yangi bilimlarga ega bo‘ldilar, yangi tanishuvlar orttirdilar va o‘z kelajagi sari muhim qadamlar qo‘ydilar.
Har bir ishtirokchi bilan faxrlanamiz va ushbu tadbirning bir qismi bo‘lgan barchaga minnatdorchilik bildiramiz!
#ADC#YouthSummit2026#InternationalSummit#Leadership#Education#FutureLeaders
📞 742261078
📲 Telegram: @admofadc
🌟 ADC International Youth Summit 2026
Yilning eng yirik va ilhomlantiruvchi tadbirlaridan biri — ADC Xalqaro Yoshlar Sammiti o‘z yakuniga yetdi!🌍✨
Ushbu sammit turli mamlakatlardan kelgan eng faol yoshlar, yetakchilar va ekspertlarni bir nuqtada birlashtirdi. Ishtirokchilar tajriba almashishdi, yangi bilimlar olishdi va kelajak sari muhim qadam tashlashdi. Biz har bir ishtirokchi bilan faxrlanamiz!
✨ADC International Youth Summit 2026✨
We are excited to share some of the brightest moments from one of the most large-scale and inspiring events of the year — ADC International Youth Summit 2026!
This summit brought together active and ambitious youth, leaders, speakers, and experts from different countries. Throughout these productive days, participants exchanged ideas, gained new knowledge, built valuable connections, and took important steps toward their future.
We are proud of every participant and grateful to everyone who became part of this incredible event!
#ADC#YouthSummit2026#InternationalSummit#Leadership#Education#FutureLeaders#YoshlarSammati
📞 742261078
📲 Telegram: @admofadc
🌟 ADC International Youth Summit 2026
Yilning eng yirik va ilhomlantiruvchi tadbirlaridan biri — ADC Xalqaro Yoshlar Sammati o‘z yakuniga yetdi!🌍✨
Ushbu sammit turli mamlakatlardan kelgan eng faol yoshlar, yetakchilar va ekspertlarni bir nuqtada birlashtirdi. Ishtirokchilar tajriba almashishdi, yangi bilimlar olishdi va kelajak sari muhim qadam tashlashdi. Biz har bir ishtirokchi bilan faxrlanamiz!
✨ADC International Youth Summit 2026✨
We are excited to share some of the brightest moments from one of the most large-scale and inspiring events of the year — ADC International Youth Summit 2026!
This summit brought together active and ambitious youth, leaders, speakers, and experts from different countries. Throughout these productive days, participants exchanged ideas, gained new knowledge, built valuable connections, and took important steps toward their future.
We are proud of every participant and grateful to everyone who became part of this incredible event!
#ADC#YouthSummit2026#InternationalSummit#Leadership#Education#FutureLeaders#YoshlarSammati
📞 742261078
📲 Telegram: @admofadc