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Opening and closing an SSH tunnel in a shell script the smart way

I recently had the following problem:

• From an unattended shell script (called by Jenkins), run a command-line tool that accesses the MySQL database on another host.
• That tool doesn't know that the database is on another host, plus the MySQL port on that host is firewalled and not accessible from other machines.

We didn't want to open the MySQL port to the network, but it's possible to SSH from the Jenkins machine to the MySQL machine. So, basically you would do something like

ssh -L 3306:localhost:3306 remotehost

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#!/usr/bin/env bash
# file: node-name.sh

set -eu

PREFIX=history
MAXNODES=100

DEFAULT=${PREFIX}_$(uuidgen | sed 's/-//g')

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-module(ct_helper).

-compile([export_all]).

%% @doc Like ct:get_config/1, but calls error/1 if Key is not found / undefined.
%% This guarantees to fail fast if required config options are missing from
%% the config file, saving trouble with `undefined` value propagation.
%% Use alongside with the CT `require` mechanism.
%% See s2s_SUITE for an example.
-spec get_config(atom()) -> any().

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-module(agent).

-compile([export_all]).

test(CallerPid) ->
    CallerPid ! {agent, node(), self()}.

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#!/usr/bin/env bash

## Make Docker4Mac containers routable in a private network.
## This is mostly a copy-paste from the original solution.
## IT'S NOT A COMPLETE SOLUTION - this script only does the
## steps necessary every time Docker4Mac is restarted.
## Beforehand, you have to run the steps marked as ONCE yourself.
## See https://github.com/docker/for-mac/issues/155#issuecomment-320509769

set -e

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Last login: Wed Oct 25 18:19:04 on ttys005
e18:20:30 erszcz @ x4 : ~
$ erl
-bash: erl: command not found
18:20:30 erszcz @ x4 : ~
$ . ~/apps/erlang/19.3.6.2/activate
18:20:41 erszcz @ x4 : ~
$ erl
Erlang/OTP 19 [erts-8.3.5.2] [source] [64-bit] [smp:4:4] [async-threads:10] [kernel-poll:false]

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Docs chunk format proposal

Let's first look at some elixir_docs_v1 examples (Erlang syntax). The general chunk structure (from GenServer) is:

{elixir_docs_v1,
    [{docs,
         [{{'__using__',1},539,defmacro,[{'',[],'Elixir'}],false},
          {{abcast,3},

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" d closes a tab
map d closeTab

" C-d/C-u scrolls down/up
map <C-d> scrollPageDown
map <C-u> scrollPageup

" M-§ / A-§ switch to previous active tab / last used tab
map <M-§> lastUsedTab
map <A-§> lastUsedTab

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-module(my_tracer).

-compile([export_all]).

-define(il2b, iolist_to_binary).

%% Listen carefully, since I won't repeat.
%%
%% Default dbg:dhandler/2 is nice,
%% but when you want to use domain knowledge

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%% See assertEqual in $ERLANG/lib/stdlib-2.6/include/assert.hrl for the original.
-define(exmlAssertEqual(Example, Expr),
        begin
            ((fun (__X, __V) ->
                      case __V of
                          __X -> ok;
                          __V -> erlang:error({exmlAssertEqual,
                                               [{module, ?MODULE},
                                                {line, ?LINE},
                                                {expression, (??Expr)},