localhost woes -- help requested

[Ronald F. Guilmette]

In message <CA+tpaK1NKqctQqZeRg+emM8gVKWuJeveCVVx-FHsVbrkYD9Y2Q at mail.gmail.com>, 
Adam <amvandemore at gmail.com> wrote:

>On Sat, Jun 15, 2019 at 12:54 AM Ronald F. Guilmette <rfg at tristatelogic.com>
>wrote:
>> ... except for the browsers, and also one other thing (nmh outbound
>> email handling).  Now, both Firefox and Opera crash and burn, right
>> out of the gate, when started from the command line.  In both cases
>> thet do so both with entirely cryptic failure messages.
>>
>> But here's the kicker... I futzed around with this awhile and found
>> out that if I just change the default value of the DISPLAY environment
>> variable from "localhost:0.0" to ":0.0" then both browsers *do* then
>> start up successfully from the command line.
>>
>> So, um, what the bleep did I do wrong?
>>
>> Here's the output of the command "getent hosts localhost":
>>
>> ::1               localhost
>> 127.0.0.1         localhost  localhost.tristatelogic.com
>>
>>
>> Any hints for how I can debug this mess would be appreciated.
>>
>
>Do you have local_unbound running?  It's probably caching the result.
>
>/etc/rc.d/local_unbound stop
>
>Then try your changes to /etc/hosts

I have now rebooted the system multiple times, from a cold start, and
this has had *no* effect on the output generated by "getent hosts localhost".

That is *still* showing me that there exists a mapping from "localhost"
to an IPv6 address, even though I commented that out in my /etc/hosts
file.

I really would like to understand why manual edits to /etc/hosts seem
to have no effect whatosoever.  And more importantly, I'd really still
like to know whey X applications cannot seem to connect to the X server
when and if DISPLAY is set to localhost:0.0 while they have no problem
doing so when DISPLAY is instead set to :0.0