starting erlang app from command line

[Håkan Stenholm]

CyBerHigh wrote:

> I was wondering if it was possible to start an erlang app from the 
> command line.  Like a simple shell script you would just put in the 
> shebang and mark it as executable then run it.  However this doesn't 
> seem to be possible with erlang.  Anything I write seems to have to be 
> done from the erlang shell.  Are there any workarounds?
>
> Thanks
> CyBerHigh
>
Read the 'erl' man page, this can be done with the '-s' or '-run' flag:

        -run Mod [Fun [Args]]:
             Passes the -run flag to the init:boot() routine.

         -s Mod [Fun [Args]]:
             Passes the -s flag to the init:boot() routine.

init documentation:

|-run Module [Function [Args]]|
    Evaluate the specified function during system initialization.
    |Function| defaults to |start| and |Args| to |[]|. If the function
    call ends abnormally, the Erlang runtime system stops with an error
    message.
    The arguments after |-run| are used as arguments to Erlang
    functions. All arguments are passed as strings. For example:

$ *erl -run foo -run foo bar -run foo bar baz 1 2*
        
    

    This starts the Erlang runtime system and then evaluates the
    following Erlang functions:

foo:start()
foo:bar()
foo:bar(["baz", "1", "2"]).
        
    

    The functions are executed sequentially in the initialization
    process, which then terminates normally and passes control to the
    user. This means that a |-run| call which does not terminate will
    block further processing; to avoid this, use some variant of |spawn|
    in such cases.
|-s Module [Function [Args]]|
    Evaluate the specified function during system initialization.
    |Function| defaults to |start| and |Args| to |[]|. If the function
    call ends abnormally, the Erlang runtime system stops with an error
    message.
    The arguments after |-s| are used as arguments to Erlang functions.
    All arguments are passed as atoms. For example:

$ *erl -s foo -s foo bar -s foo bar baz 1 2*
        
    

    This starts the Erlang runtime system and then evaluates the
    following Erlang functions:

foo:start()
foo:bar()
foo:bar([baz, '1', '2']).
        
    

    The functions are executed sequentially in the initialization
    process, which then terminates normally and passes control to the
    user. This means that a |-s| call which does not terminate will
    block further processing; to avoid this, use some variant of |spawn|
    in such cases.
    Due to the limited length of atoms, it is recommended that |-run| be
    used instead.


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