Fish uses options on the `set` command to manipulate shell variables.

Unset a variable with the `-e` or `--erase` option.

    set -e myvar 

Additionally you can define a function

    function unset
      set --erase $argv
    end
    
    funcsave unset

or an abbreviation
    
    abbr --add unset &#39;set --erase&#39;

or an alias in `~/.config/fish/config.fish`

    alias unset &#39;set --erase&#39;


Currently i am starting RabbitMQ Docker container using the default RabbitMQ image from [DockerHub][1]. Using the following commands.

    docker run --restart=always \
    -d \
    -e RABBITMQ_NODENAME=rabbitmq \
    -v /opt/docker/rabbitmq/data:/var/lib/rabbitmq/mnesia/rabbitmq \
    -p 5672:5672 \
    -p 15672:15672 \
    --name rabbitmq rabbitmq:3-management

I have a need where i want to provide defaults users / and virtual-hosts when the image is first started. For example to create a default &#39;test-user&#39;.

Currently i have to do that manually by using the management plugin and adding the users / virtual-hosts via the web ui. Is there a way i can provide default settings when starting the RabbitMQ image?

  [1]: https://registry.hub.docker.com/_/rabbitmq/

How to add initial users when starting a RabbitMQ Docker container?

I plan to split my monolthic server up into many small docker containers but haven&#39;t found a good solution for &quot;inter-container communication&quot; yet. This is my target scenario:

![Target scenario][1]

I know how to link containers together and how to expose ports, but none of these solutions are satisfying to me. 

**Is there any solution to communicate via hostnames (container names) between the containers like in a traditional server network?**

  [1]: http://i.stack.imgur.com/USA2n.png

How to communicate between Docker containers via &quot;hostname&quot;

In bash I can unset a variable with 
   
    unset myvar

In fish I get 
  
    fish: Unknown command &#39;unset&#39;

What&#39;s the equivalent for unset in fish.

How do I unset a variable in the fish shell?

In bash I can unset a variable with
<pre><code class="hljs language-bash">unset myvar
</code></pre>
In fish I get
<pre><code class="hljs language-bash">fish: Unknown command 'unset'
</code></pre>
What's the equivalent for unset in fish.

I know this has been an issue for a while and I found a lot of discussion about it, however I didn&#39;t get which would be finally a way to get it done: pipe both, stdout and stderr. In bash, this would be simply:

    cmd 2&gt;&amp;1 | cmd2



pipe both, stdout and stderr in the fish shell

In the bash shell, I could `echo $?` to get the exit code of a program run on the cli. What is the equivalent in the fish shell? Can&#39;t seem to find this in the docs.

Content Type	Original Author	Original Content on Stackoverflow
Question	J0hnG4lt	View Question on Stackoverflow
Solution 1 - Fish	J0hnG4lt	View Answer on Stackoverflow

How do I unset a variable in the fish shell?

Fish Problem Overview

Fish Solutions

Solution 1 - Fish

How to communicate between Docker containers via "hostname"

How to add initial users when starting a RabbitMQ Docker container?

Attributions