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catching a signal !

Posted on 2000-02-16
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Last Modified: 2008-03-06
I want to catch the SIGINT signal without using the pause( ) call in
my program.Basically I should be able to catch a signal without having
to wait for the signal to occur. My signal handler should get executed
whenever the signal gets delivered to my process.

Currently I have to use pause(. )

Is there a way out...

Kindly let me know.

Regards,
arut
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Comment
Question by:arut
5 Comments
 
LVL 40

Accepted Solution

by:
jlevie earned 50 total points
ID: 2531773
Yep, you need to register a signal handler to catch the exception. Take a look at the man pages for signal() and sigaction() and friends.
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Expert Comment

by:montenegro
ID: 2533268
It is easy to catch a signal without pause(), like this:

use the function "signal" to install a signal handler ( a function made by you that is called when your process receives a certain signal), in your case:

signal(SIGINT, handler);

where "handler" is a function made by you with this aspect (it can have any other name):

void handler(int signo)
{
      here you do whatever you whant to do when SIGINT is catched...

}

signo is the number of the signal that called this handler , in your case SIGINT.

try it...
            montenegro.
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Author Comment

by:arut
ID: 2533935
I have registered a signal handler but the handler does
not get executed because the signal itself does not
get delivered unless the program has a pause( )

All I want is ...

signal(SIGINT,handler);

do some processing...

if signal has come the handler gets executed automatically


-------------------------------------------

I don't want to use a pause( ), which suspends the process till the signal is received.

If I wait for the signal I can't do other work in the program...

Whenevr the signal comes handler should be executed.
Currently I am not able to do this without pause ( ).
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LVL 40

Expert Comment

by:jlevie
ID: 2535133
Well, then it may not be coded correctly. The following is a little demonstration program that works:

cat >gork.c <<EOF
#include <stdio.h>

void catcher()
{
  printf("Caught SIGINT\n");
  exit(1);
}
#include <signal.h>

main()
{
  /*
   * Register my signal handler
   */
  signal(SIGINT, &catcher);
  (void) getchar();
  printf("Normal exit\n");
  exit(0);
}
EOF

Compile it and run it. It'll wait for either something to be typed at the keyboard or a SIGINT to be delivered.
0
 

Expert Comment

by:abhishekpatel
ID: 2584569
use the following

signal(SIGINT,sig_catch);

 when SIGINT event occurs the function named "sig_catch" will be
executed. so keep the code inside the sig_catch function which must me executed when SIGINT occurs.
         here u can do other work when the SIGINT occurs it executes the sig_catch function.u need not have to use pause.
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