我正在尝试使用 crontab 每五分钟自动重启 smokeping(用于特定测试),但不幸的是,它似乎不起作用。
> sudo crontab -e
...
#Restart smokeping every five minutes
*/5 * * * * service smokeping restart
我做错了什么? syslog 上没有信息。
答案1
它不起作用的原因是 cron 的默认值PATH
是硬编码的,它看起来像这样:
#ifndef _PATH_DEFPATH
# define _PATH_DEFPATH "/usr/bin:/bin"
#endif
https://salsa.debian.org/debian/cron/blob/52bacc70b592d354efff8231375bf2d51bd4ef52/pathnames.h#L77
更具体地说,service
无法找到该命令。如果您尝试执行,which service
您将得到类似以下内容: 这就是为什么在 crontab 中/usr/sbin/service
明确设置变量可能会有所帮助的原因。PATH
完整的 crontab 示例如下:
# 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