polaris/loading-erlang-app.md

## loading-erlang-app.md

      
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              loading-erlang-app.md
            
          
    Erlang Application Loading

directory layout
./hello_app.erl
./ebin
  ./hello.app

code
% hello_app.erl
-module(hello_app).

-behaviour(application).

-export([start/2, stop/1]).

start(_StartType, _StartArgs) ->
    io:fwrite("hello world\n").

stop(_State) ->
    ok.

% ebin/hello.app
{application,hello,
  [{applications,[kernel,stdlib]},
   {mod,{hello_app,[]}},
   {modules,[]}]}.

first you need to compile the code
> erlc hello_app.erl

now move the beam file to the ebin directory
> mv hello_app.beam ebin/

load and start the application
> cd ./ebin
> erl

Eshell V6.0
1> application:load(hello).
ok
2> application:loaded_applications().
[{kernel,"ERTS  CXC 138 10","3.0"},
 {hello,[],[]},
 {stdlib,"ERTS  CXC 138 10","2.0"}]
3> application:start(hello).
hello world
{error,{bad_return,{{hello_app,start,[normal,[]]},ok}}}

=INFO REPORT==== 17-Apr-2014::00:21:22 ===
    application: hello
    exited: {bad_return,{{hello_app,start,[normal,[]]},ok}}
    type: temporary