[erlang-questions] Can werl be detached?

John Ashmun <>
Wed May 25 23:20:07 CEST 2016


I'm running an old version of Erlang for the usual reasons:  everything I've tried with it works fine & I have no experience upgrading Erlang installations, but lots of experience with other upgrade attempts that were disastrous.

I have R16B01 on a laptop that I use to hold backup copies of my projects (& occasionally to determine whether what I write works on a different version of Erlang).  I will try using -detached there & then upgrade it to R18 or whatever the latest stable release is & try it again using that version.

BTW, the wx demo is going to help my guesswork with wx a lot.

Sent from my iPhone

> On May 25, 2016, at 1:22 PM, Dan Gudmundsson <> wrote:
> 
> Hmm,
> It works fine for me on Windows 10 from msys2 with erlang in the path 
> and from cmd shell without erlang in the path:
> 
> C:\Users\familjen>"c:\Program Files (x86)\erl7.3\bin\werl" -run wx demo
> 
> C:\Users\familjen>"c:\Program Files (x86)\erl7.3\bin\werl" -detached -run wx demo
> 
> Oh noticed the version you are running...
> 
> It also works for me with 17.0 i.e. erl-6.0 which is the oldest I have installed here at home.
> 
> Why are you using an old version of erlang?
> Can you try a newer version and see if that works?
> 
> 
>> On Wed, May 25, 2016 at 9:49 PM John Ashmun <> wrote:
>> I just found time to try what you suggested with the wx demo, but I got the same pop up Windows error message as when I try to run my release with -detached.
>> 
>> I added ...\erts-5.9\bin to %Path% and tried again but it failed again with the same error message.
>> 
>> Sent from my iPhone
>> 
>>> On May 18, 2016, at 12:02 AM, Dan Gudmundsson <> wrote:
>>> 
>>> At least this works as it should:
>>> 
>>> werl -detached -run wx demo 
>>> 
>>> 
>>>> On Wed, May 18, 2016 at 3:48 AM John R. Ashmun <> wrote:
>>>> 
>>>> 
>>>>> On Tue, May 17, 2016 at 6:32 PM, zxq9 <> wrote:
>>>>> On Tuesday 17 May 2016 16:47:35 John R. Ashmun wrote:
>>>>> > Perhaps my subject is not quite the correct question.  Here's my context:
>>>>> >
>>>>> > I'm beginning to recreate in Erlang on Microsoft Windows 10 a public domain
>>>>> > program I used to enjoy on my Commodore Amiga:  mATC was a game in which
>>>>> > the user acted as a military Air Traffic Controller.  I am using a wx
>>>>> > window to draw the player's map with aircraft data blocks overlaid.  I
>>>>> > don't have a use for the initial window that opens when werl is started.
>>>>> 
>>>>> Awesome!
>>>>> 
>>>>> > If I use this Command Prompt batch file, mATC.bat:
>>>>> >
>>>>> > werl -pa ebin -pa mATC_app\ebin -detached -boot mATC -config sys
>>>>> >
>>>>> > a Windows error message window appears that says:
>>>>> >
>>>>> > "Failed to execute C:\Program Files\erl5.9\erts5.9\bin\beam.smp.dll
>>>>> >  The system cannot find the file specified."
>>>>> >
>>>>> > The DLL is actually present at that location, and of course everything runs
>>>>> > well when I don't use -detached.
>>>>> 
>>>>> Hrm... that seems odd, but I have to admit I have no experience running
>>>>> actual releases on Windows. What I usually do instead is have the runtime
>>>>> installed on the Windows machine, unpack project code and kick things off
>>>>> with an escript that builds and then launches the code I want to run.
>>>>> 
>>>>> Changing from releases to from-source build->run may require a bit of
>>>>> shuffling -- and may or may not be worth it depending on the project.
>>>>> But this has been very effective and lightweight for my purposes.
>>>>> 
>>>>> Like everything else on Windows there are a few quirks to making escripts
>>>>> a click-to-run experience (specifying full path to "escript.exe" instead
>>>>> of "escript" in your launcher, space for unheeded shebang, etc.). I've
>>>>> wanted for a few years now to formalize and simplify a solution to this...
>>>>> but real life gets in the way of the things I wish I could do as community
>>>>> project work. :-(
>>>>> 
>>>>> The escript-to-bootstrap approach has made my Erlang GUI experience on
>>>>> Windows fairly painless -- I can develop on Linux or BSD and almost always
>>>>> get away with relying on anything that works there (to include wx) working
>>>>> pretty much the same way on Windows.
>>>>> 
>>>>> I have not tried this on Windows 10 yet, but I assume it will continue to
>>>>> work the same way it does on Windows 7 and 8.1.
>>>>> 
>>>>> -Craig
>>>>> _______________________________________________
>>>>> erlang-questions mailing list
>>>>> 
>>>>> http://erlang.org/mailman/listinfo/erlang-questions
>>>> 
>>>> I will look into escript, thanks.
>>>> 
>>>> John
>>>> _______________________________________________
>>>> erlang-questions mailing list
>>>> 
>>>> http://erlang.org/mailman/listinfo/erlang-questions
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