I've lost sudo access and I don't really understand why

[Tom H]

On Wed, Mar 18, 2020 at 11:19 PM Karl Auer <kauer at biplane.com.au> wrote:
> On Wed, 2020-03-18 at 21:28 +0000, Chris Green wrote:
>>
>> So (unless using the -a option) usermod removes group membership that
>> isn't specifically stated.  Surely there's an easier way to add
>> oneself to an extra group.
>
> Personally I almost always modify /etc/groups directly (i.e., with a
> text editor) unless the operation is scripted. It has never failed me
> in well over 30 years of Unixing.

I hope that you use "vigr" (and "vipw" for "/etc/passwd").