[Xenomai-core] system() question

[Xenomai-core] system() question

[Stéphane ANCELOT]

Is there a way to launch my realtime task from another linux program 
using system() C call ?

I have tried it , but when system call dies my rt task dies too ...
any idea ?
steph

Re: [Xenomai-core] system() question

[Gilles Chanteperdrix]

Stéphane ANCELOT wrote:
> Is there a way to launch my realtime task from another linux program 
> using system() C call ?
> 
> I have tried it , but when system call dies my rt task dies too ...
> any idea ?

Why does the system call die ? Do you observe the same behaviour with
non xenomai applications ?

-- 
                                                 Gilles Chanteperdrix

Re: [Xenomai-core] system() question

[Stéphane ANCELOT]

my linux user task uses a system() call in order to call a bash script 
to restart the realtime task as follow :

user interface C call :
system("restart_task.sh");
give back hand to user interface
....




bash script restart_task.sh :
killall -15 mytask
sleep 2
mytask &


system call dies because sh script has been launched

Gilles Chanteperdrix wrote:
> Stéphane ANCELOT wrote:
>> Is there a way to launch my realtime task from another linux program 
>> using system() C call ?
>>
>> I have tried it , but when system call dies my rt task dies too ...
>> any idea ?
> 
> Why does the system call die ? Do you observe the same behaviour with
> non xenomai applications ?
> 

Re: [Xenomai-core] system() question

[Gilles Chanteperdrix]

Stéphane ANCELOT wrote:
 > my linux user task uses a system() call in order to call a bash script 
 > to restart the realtime task as follow :
 > 
 > user interface C call :
 > system("restart_task.sh");
 > give back hand to user interface
 > ....
 > 
 > 
 > 
 > 
 > bash script restart_task.sh :
 > killall -15 mytask
 > sleep 2
 > mytask &
 > 
 > 
 > system call dies because sh script has been launched

Try calling daemon(0,0) in mytask instead of using "&" to make it run in
the background.

-- 


					    Gilles Chanteperdrix.

Re: [Xenomai-core] system() question

[Stéphane ANCELOT]

I tried it, but did not help, I manged to do the trick using 
start-stop-daemon

Gilles Chanteperdrix wrote:
> Stéphane ANCELOT wrote:
>  > my linux user task uses a system() call in order to call a bash script 
>  > to restart the realtime task as follow :
>  > 
>  > user interface C call :
>  > system("restart_task.sh");
>  > give back hand to user interface
>  > ....
>  > 
>  > 
>  > 
>  > 
>  > bash script restart_task.sh :
>  > killall -15 mytask
>  > sleep 2
>  > mytask &
>  > 
>  > 
>  > system call dies because sh script has been launched
> 
> Try calling daemon(0,0) in mytask instead of using "&" to make it run in
> the background.
> 

Re: [Xenomai-core] system() question

[Gilles Chanteperdrix]

Stéphane ANCELOT wrote:
> I tried it, but did not help, I manged to do the trick using 
> start-stop-daemon

If I understand correctly the problem you have, it is not related at all
with Xenomai. What you want is to make your application a real daemon.
The easy way to do this is to call the glibc function named "daemon" the
hard way is to call fork twice, call setsid and setpgrp.
start-stop-daemon will not do the trick.

-- 
                                                 Gilles Chanteperdrix

Re: [Xenomai-core] system() question

[Gilles Chanteperdrix]

Gilles Chanteperdrix wrote:
> Stéphane ANCELOT wrote:
> 
>>I tried it, but did not help, I manged to do the trick using 
>>start-stop-daemon
> 
> 
> If I understand correctly the problem you have, it is not related at all
> with Xenomai. What you want is to make your application a real daemon.
> The easy way to do this is to call the glibc function named "daemon" the
> hard way is to call fork twice, call setsid and setpgrp.
> start-stop-daemon will not do the trick.
> 

It is enough to fork only once, to call setsid in the child and call
_exit in the father. That is what the daemon function does. Anyway, this
is basic unix knowledge, for which you will get more acurate details at
other places.

-- 
                                                 Gilles Chanteperdrix