Ubuntu 20.04服务器Cron任务无法执行的问题咨询

我最近在Ubuntu 20.04服务器上碰到个头疼的问题：设置好的Cron任务一直不执行。试了各种排查方法后，才发现是/etc/pam.d/common-auth文件里的几行配置被注释掉了，取消注释后问题就解决了！

需要取消注释的内容如下：

auth    [success=1 default=ignore]      pam_unix.so nullok
auth    requisite                       pam_deny.so
auth    required                        pam_permit.so
auth    optional                        pam_cap.so

顺带贴一下这个文件的官方说明，方便大家理解配置的作用：

This file is included from other service-specific PAM config files, #

and should contain a list of the authentication modules that define #

the central authentication scheme for use on the system #

(e.g., /etc/shadow, LDAP, Kerberos, etc.). The default is to use the #

traditional Unix authentication mechanisms. #

#

As of pam 1.0.1-6, this file is managed by pam-auth-update by default. #

To take advantage of this, it is recommended that you configure any #

local modules either before or after the default block, and use #

pam-auth-update to manage selection of other modules. See #

pam-auth-update(8) for details. #

希望这个踩坑经验能帮到遇到同样问题的朋友！

备注：内容来源于stack exchange，提问作者anjanesh