UNIX password file id group

https://www.cyberciti.biz/faq/understanding-etcpasswd-file-format/

http://www.yourownlinux.com/2015/07/etc-passwd-file-format-in-linux-explained.html

man passwd (HPUX)

On a non-shadowed standard system, all password fields contain the actual encrypted password. 

On a shadowed standard system, all password fields contain an `x', while the actual encrypted passwords reside in /etc/shadow. 

On a trusted system, all password fields contain a `*' and the actual encrypted passwords reside in the Protected Password Database.