现象

认证日志 /var/log/auth.log 反复出现CRON信息

Aug  8 01:09:01 rpi0w CRON[15394]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug  8 01:09:01 rpi0w CRON[15394]: pam_unix(cron:session): session closed for user root
Aug  8 01:17:02 rpi0w CRON[15403]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug  8 01:17:02 rpi0w CRON[15403]: pam_unix(cron:session): session closed for user root
Aug  8 01:39:01 rpi0w CRON[15443]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug  8 01:39:01 rpi0w CRON[15443]: pam_unix(cron:session): session closed for user root
Aug  8 02:09:01 rpi0w CRON[15477]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug  8 02:09:01 rpi0w CRON[15477]: pam_unix(cron:session): session closed for user root
Aug  8 02:17:01 rpi0w CRON[15499]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug  8 02:17:01 rpi0w CRON[15499]: pam_unix(cron:session): session closed for user root
Aug  8 02:39:01 rpi0w CRON[15526]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug  8 02:39:01 rpi0w CRON[15526]: pam_unix(cron:session): session closed for user ?root

方法

1. 修改 common-session-noninteractive

sudo nano /etc/pam.d/common-session-noninteractive

2. 找到这一行

session required        pam_unix.so 

3. 前排添加

session     [success=1 default=ignore] pam_succeed_if.so service in cron quiet use_uid

4. 保存退出

5. 重启 crond 服务

sudo systemctl restart cron