在我的 Ubuntu Server 16.04.1 上，我无法在 cron 中运行两个作业。我的 crontab 如下所示
root@vps:~# crontab -l
# 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
0 6 * * * /usr/sbin/apachectl -k graceful
0 3 * * * /usr/bin/letsencrypt renew
我也尝试使用 apachectl 和 letsencrypt 的相对路径，但没有任何变化。
当我直接运行命令时，一切正常。但是 cron 中的作业未执行。
请问可能是什么问题？
答案1
您可以检查两件事：
添加日志记录：
0 6 * * * /usr/sbin/apachectl -k graceful >> /tmp/a.log 2>&1 0 3 * * * /usr/bin/letsencrypt renew >> /tmp/b.log 2>&1检查日志：
cat /tmp/a.log && cat /tmp/b.log tail -f /var/log/syslog | grep -i cron
答案2
我认为我们可以认为这个问题已经解决了。cron 作业正在运行，只是证书需要更新，运气不好（或者运气不好）。