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digitalmars.D.learn - system's "kill <pid>" signal

reply Konstantin Kutsevalov <adamasantares gmail.com> writes:
Hi,

is there a way to catch system signal of "kill" command or 
"shutdown"?

PS: are there some other ways also to send signals to running a D 
application?
Nov 04 2016
next sibling parent Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Saturday, 5 November 2016 at 02:24:00 UTC, Konstantin 
Kutsevalov wrote:

 Hi,

 is there a way to catch system signal of "kill" command or 
 "shutdown"?

 PS: are there some other ways also to send signals to running a 
 D application?


have a look in std.process

I don't think you can catch kill.
Nov 04 2016
prev sibling parent reply Basile B. <b2.temp gmx.com> writes:
On Saturday, 5 November 2016 at 02:24:00 UTC, Konstantin 
Kutsevalov wrote:

 Hi,

 is there a way to catch system signal of "kill" command or 
 "shutdown"?


During the Run-time:
====================

You can register a signal callback, like in this sample (hit 
CTRL+C once running in a terminal):

import std.stdio;
import core.sys.posix.signal;

bool doQuit;

extern(C) void handler(int num) nothrow  nogc  system
{
     printf("Caught signal %d\n",num);
     doQuit = true;
}

void main(string[] args)
{
     signal(SIGINT, &handler);
     while(true)
     {
         import core.thread;
         Thread.sleep(dur!"msecs"(50));
         if (doQuit)
             break;
     }
}


After termination:
==================

if (tryWait(PID)[0] == true) then the value carried by 
tryWait(PID)[1] will tell you if the process has exited because 
of a signal whatever it's, e.g SIGKILL, SIGTERM, SIGINT, ...
Nov 04 2016
next sibling parent reply Basile B. <b2.temp gmx.com> writes:
On Saturday, 5 November 2016 at 06:17:51 UTC, Basile B. wrote:

 On Saturday, 5 November 2016 at 02:24:00 UTC, Konstantin 
 Kutsevalov wrote:

 Hi,

 is there a way to catch system signal of "kill" command or 
 "shutdown"?


 During the Run-time:
 ====================

 You can register a signal callback, like in this sample (hit 
 CTRL+C once running in a terminal):

 import std.stdio;
 import core.sys.posix.signal;

 bool doQuit;

 extern(C) void handler(int num) nothrow  nogc  system
 {
     printf("Caught signal %d\n",num);
     doQuit = true;
 }

 void main(string[] args)
 {
     signal(SIGINT, &handler);
     while(true)
     {
         import core.thread;
         Thread.sleep(dur!"msecs"(50));
         if (doQuit)
             break;
     }
 }


 After termination:
 ==================

 if (tryWait(PID)[0] == true) then the value carried by 
 tryWait(PID)[1] will tell you if the process has exited because 
 of a signal whatever it's, e.g SIGKILL, SIGTERM, SIGINT, ...


3rd option, from my Windows times I remember that people tend to 
use launchers
to handle the real application, i.e a process that launches the 
main process. Then the launcher can have a thread that checks the 
PID (like in "After Term..."). If SIGKILL isn't handled by a 
signal() callback then this could be an option.

Do you have to check if a server crashes or something like that ?
Nov 05 2016
parent reply Konstantin Kutsevalov <adamasantares gmail.com> writes:
On Saturday, 5 November 2016 at 07:52:53 UTC, Basile B. wrote:

 On Saturday, 5 November 2016 at 06:17:51 UTC, Basile B. wrote:
 3rd option, from my Windows times I remember that people tend 
 to use launchers
 to handle the real application, i.e a process that launches the 
 main process. Then the launcher can have a thread that checks 
 the PID (like in "After Term..."). If SIGKILL isn't handled by 
 a signal() callback then this could be an option.

 Do you have to check if a server crashes or something like that 
 ?


not a system crash. just a signal of sistems shutdown or process 
kill.
Nov 06 2016
next sibling parent Konstantin Kutsevalov <adamasantares gmail.com> writes:
On Sunday, 6 November 2016 at 16:05:44 UTC, Konstantin Kutsevalov 
wrote:

 On Saturday, 5 November 2016 at 07:52:53 UTC, Basile B. wrote:

 On Saturday, 5 November 2016 at 06:17:51 UTC, Basile B. wrote:
 3rd option, from my Windows times I remember that people tend 
 to use launchers
 to handle the real application, i.e a process that launches 
 the main process. Then the launcher can have a thread that 
 checks the PID (like in "After Term..."). If SIGKILL isn't 
 handled by a signal() callback then this could be an option.

 Do you have to check if a server crashes or something like 
 that ?


 not a system crash. just a signal of sistems shutdown or 
 process kill.


*of system
Nov 06 2016
prev sibling parent Steven Schveighoffer <schveiguy yahoo.com> writes:
On 11/6/16 11:05 AM, Konstantin Kutsevalov wrote:

 On Saturday, 5 November 2016 at 07:52:53 UTC, Basile B. wrote:

 On Saturday, 5 November 2016 at 06:17:51 UTC, Basile B. wrote:
 3rd option, from my Windows times I remember that people tend to use
 launchers
 to handle the real application, i.e a process that launches the main
 process. Then the launcher can have a thread that checks the PID (like
 in "After Term..."). If SIGKILL isn't handled by a signal() callback
 then this could be an option.

 Do you have to check if a server crashes or something like that ?


 not a system crash. just a signal of sistems shutdown or process kill.


You can catch signals, but some the OS does not let you catch.

IIRC, Posix systems on shutdown first send a "TERM" signal (15) which is 
the default signal for the kill command line as well. If the process 
does not clean up within a certain timeout, then it is sent the "KILL" 
signal (9), which CANNOT be caught.

What you want is to handle process cleanup on the TERM signal.

-Steve
Nov 06 2016
prev sibling parent Konstantin Kutsevalov <adamasantares gmail.com> writes:
On Saturday, 5 November 2016 at 06:17:51 UTC, Basile B. wrote:

 On Saturday, 5 November 2016 at 02:24:00 UTC, Konstantin 
 Kutsevalov wrote:

 Hi,

 is there a way to catch system signal of "kill" command or 
 "shutdown"?


 During the Run-time:
 ====================

 You can register a signal callback, like in this sample (hit 
 CTRL+C once running in a terminal):


 After termination:
 ==================

 if (tryWait(PID)[0] == true) then the value carried by 
 tryWait(PID)[1] will tell you if the process has exited because 
 of a signal whatever it's, e.g SIGKILL, SIGTERM, SIGINT, ...


Thank you!
Nov 06 2016