如何让bash脚本循环到特定时间

Question

通常运行无限bash循环,我执行以下操作:

while true; do
    echo test
    sleep 1
done

如果相反,我想做一个无限循环的循环,只要它早于20:00.有没有办法在bash中这样做？

Answer 1

You can use date to print the hours and then compare to the one you are looking for:

while [ $(date "+%H") -lt 20 ]; do
    echo "test"
    sleep 1
done

as date "+%H" shows the current hour, it keeps checking if we are already there or in a "smaller" hour.

Answer 2

如果您想要特定的日期，而不仅仅是完整的时间，请尝试比较 Unix 时间：

while [ $(date +%s) -lt $(date --date="2016-11-04T20:00:00" +%s) ]; do
    echo test
    sleep 1
done