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crontab 不是自動重啟服務

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crontab 不是自動重啟服務

我試圖使用 crontab 每五分鐘自動重新啟動一次吸煙（用於特定測試），但不幸的是，它似乎不起作用。

> sudo crontab -e
 ...

#Restart smokeping every five minutes
*/5 * * * * service smokeping restart

我究竟做錯了什麼？ syslog 上沒有資訊。

答案1

它不起作用的原因是 cron 的預設值PATH是硬編碼的，看起來像這樣：

#ifndef _PATH_DEFPATH
# define _PATH_DEFPATH "/usr/bin:/bin"
#endif

https://salsa.debian.org/debian/cron/blob/52bacc70b592d354efff8231375bf2d51bd4ef52/pathnames.h#L77

更具體地說，service找不到該指令。如果您嘗試執行，which service您將得到類似的資訊： 這就是為什麼在 crontab 中/usr/sbin/service 明確設定變數可能會有所幫助。PATH

完整的 crontab 範例如下：

# Edit this file to introduce tasks to be run by cron.
# 
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
# 
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').# 
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
# 
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# 
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
# 
# For more information see the manual pages of crontab(5) and cron(8)
# 
# m h  dom mon dow   command

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

*/5 * * * * service smokeping restart

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