Define group administrators

Administer `/etc/group` and `/etc/gshadow`.
More information: <https://manned.org/gpasswd>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

sudo gpasswd -A {{user1,user2}} {{group}}

click the source code to copy install gpasswd on any operating system with command-not-found.com