The attachment is the source code for a procedure that I have used for seven
years on three different flavors of UNIX -- IRIX 6.3 (mips), Solaris 2.5.1
(sparc), and
Linux (ix86).

This procedure is called immediately after any initialization (e.g.,
command-line
argument processing) in the main program.

The main program declares a Boolean variable named Is_Parent which is
initialized
to True.

That variable is set by this procedure in the child process, so, immediately
after the
call to this procedure,  the main program should contain the following
sequence:
if Is_Parent then
   return;
end if;

Thus, the parent procedure will terminate, thus returning control to its
invoking
shell, and the code following the above sequence continues as the child
process
which has been made into a true UNIX daemon -- i.e:

   1. The process has been detached from its controlling terminal, and has
been
       made the process group leader of a new process group.

  2. The current working directory is changed to "/" in case the directory
from
      which the daemon was started should become uncounted -- i.e, the current
      directory is changed to one which for sure cannot be uncounted.

  3.  Finally, the file creation mask is set appropriately.

This procedure uses the POSIX/Ada95 bindings from the florist package set.

I do not believe the earlier respondents to your request understood just what
is meant by "UNIX daemon."  This code was developed from W. Richard
Stevens' book "Advanced Programming in the Unix Environment," and was
originally implemented in Ada83, with an earlier implementation of
POSIX/Ada83 bindings  called "forest" a sort of predecessor to "florist."

----- Original Message -----
From: "Stefan Nobis" <stefan@snobis.de>
Newsgroups: comp.lang.ada
To: <comp.lang.ada@ada.eu.org>
Sent: July 01, 2001 7:41 AM
Subject: Unix-daemons in Ada


> Hi.
>
> I'm learning Ada and i tried to write a simple Unix daemon in Ada (a very
> simple web server). I want the main process, which is attached to a tty, to
> exit, something like
>
> if (fork()) exit 0;
> else do_real_work();
>
> in C. I played a little bit with Adas Tasks, but i have no clue how to
> implement the above in Ada.
>
> --
> Until the next mail...,
> Stefan.
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