How to solve crontab time zone mismatch with system time zone

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I have a program which need to run everyday at certain time. It has some package which cannot install in alpine Linux, which means I cannot deploy this in qinglong panel. So I decided to use crontab. However I found it did not run at the certain time I hoped. At first, I think it must because the system time zone is wrong and indeed I had not modify the system time zone.

How to modify system time zone on Linux (Ubuntu in my environment)

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date # this shows your current time zone
sudo apt install tzdata
sudo dpkg-reconfigure tzdata # then choose the time zone you want
ls -lh /etc/localtime
date # check whether it is effective

However, the next day, the program did not wrong properly as well. Then I did some search and found the answer. The crontab has its own time zone environment which means we need to clarify it ourself.

How to set time zone for crontab

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sudo vim /etc/crontab
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# add the following lines into your crontab file, you can add it after SHELL=/bin/sh, replace the exact time zone you need, do not just copy and paste my time zone simply.
CRON_TZ=Asia/Shanghai
TZ=Asia/Shanghai
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service cron restart

And you will find your task will run at the time you set.

Reference

  1. https://zhuanlan.zhihu.com/p/123124036