[Gambas-user] Send a signal do a PID. Is it possible?

[Fabien Bodard]

Le Jeudi 17 Novembre 2005 04:26, Andre Saccomani a écrit :
> Thanks for the answer Benoit.
>
> My program is a simple GUI, and send a signal to other running program was
> just a Nice to have, and not a Must have.
> Regarding the one instance only. I just wanted to prevent the end user to
> forget that the program is already in the tray and open it again. So I
> wanted to restore the program from tray instead of open a new.
> The only one instance issue can be easily work arounded with a little of
> bash and EXEC [ ] for READ. :)
>

hum ... mabe by using a unix socket server file ?


http://binara.com/gambas-wiki/static/Gambas/GbNetSocket.html

Create a socket can allow you two thing :

- Manage the number of your launched application by the user or mabe on the 
system.

- allowing the application communication (but you need to create your 
communication protocol)

It's just an idea and i've not tested it... 


Regards,
Fabien Bodard

> Thanks again Benoit.
>
> Andre.
>
> On 11/16/05, Benoit Minisini <gambas at ...1...> wrote:
> > On Wednesday 16 November 2005 23:50, Andre Saccomani wrote:
> > > i
> > > Is there anyway to send a signal to a linux PID? and if so, is there a
> >
> > way
> >
> > > to catch these signals in a gambas application? So when I try to open a
> > > second instance of my program, it would check if is there one already
> > > running and then it could send a signal to the first instance before
> >
> > exit.
> >
> > > This signal would cause my program (the first instance) do do a
> > > dlgMain.Show, or something like this. restoring it from tray.
> > > Hi,
> > > I would like to make a software that allows only one instance of it
> > > running at same time. So when someone try to open a second instance of
> >
> > the
> >
> > > program, it would look if there is one already running, and if there
> > > is,
> >
> > I
> >
> > > would like to make this second instance to exit.
> > > But before exit, I want it to send a message to the first instance. Is
> > > there anyway to do that? send a message to a program by having its PID?
> > > If possible, how can I send a message to a PID and how do I handle
> >
> > received
> >
> > > messages?
> > > Thanks in advance,
> > > Andre
> >
> > The problem cannot be solved entirely in Gambas at the moment.
> >
> > But you first must understand that running a software "once" is more
> > subtil on
> > Unix than on Windows.
> >
> > Does "once" means:
> > - Only one process for this executable and for one user on the same
> > system?
> > - Only one process for this executable and for one user on the same
> > display/desktop?
> >
> > With X-Window, processes and displays can have the network between them,
> > so
> > two processes from two different systems can run on the same desktop, and
> > two
> > processes from the same system can run on two different desktops.
> >
> > If your program is a GUI program, running a program "once" usually means:
> > only
> > one process for this executable for this display/desktop.
> >
> > KDE solved this problem with the DCOP protocol: the application
> > registered to
> > the DCOP server, and if it was already registered, then it knows that
> > another
> > was already started. It can then warn the first application instance with
> > a
> > DCOP message.
> >
> > It could be possible to implement this registration by storing an X11
> > property
> > in the display root window. Then, there will be the problem of sending
> > the first registered application that another one was launched. Something
> > to implement...
> >
> > Last point, there is no way to catch signals in a Gambas application.
> >
> > Regards,
> >
> > --
> > Benoit Minisini
> >
> >
> >
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