> That survey suggests one more possibility:
>
> - Split the GECOS field at the first comma.
>
> - Return the part before that comma as the "user full name".
>
> - Ignore the remainder.
>
> - If there is no comma, return the entire field as "user full name".
>
> - Maybe also expand any ampersand (&) to the username.

Here: <https://misc.lassi.io/2019/parse-gecos.c>

It only expands the first ampersand. There should be at most one.

Also, if we use this technique and return only the first comma-delimited
field from pw_gecos, then we can repurpose the same user-info:full-name
procedure for Windows and other operating systems.