[erlang-questions] Can werl be detached?

John R. Ashmun <>
Wed May 18 01:47:35 CEST 2016


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.

http://erlang.org/doc/man/werl.html

says, in part, "All flags except -oldshell work as they do for the erl
<http://erlang.org/doc/man/erl.html> command."  I don't have a UNIX-y
system available to me to learn how they work for the erl command.  (The
erl command as an interactive program is iffy in a Windows Command Prompt
window.)

In particular, the description of -detached in

http://erlang.org/doc/man/erl.html

would seem to be what I want:

"Starts the Erlang runtime system detached from the system console. Useful
for running daemons and backgrounds processes. Implies -noinput."

I want the Erlang VM to run my game without an Erlang shell's having opened
a window, and I want my game to be in control of its wx window.

Further, following what I think I learned from "Erlang and OTP in Action",
I have an OTP application being started by a boot file created from a .rel
file.  All of this is in the setting of an ancient Erlang release:  R15B.

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.

Please advise.

Regards,
John Ashmun
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