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*                                                                       *    
*  Copyright Digital Equipment Corporation 1998. All rights reserved.   *
*                                                                       *    
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*  52.227-14 Alt. III, as applicable.                                   *    
*                                                                       *    
*  This software is proprietary to and embodies the confidential        *    
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*  valid written license from Digital or an authorized sublicensor.     *    
*                                                                       *    
************************************************************************/

/*      chap_4_suspend_resume.c         */

/* This program shows how to alternately suspend and resume a   */
/* program using the signal, alarm, and pause functions.        */

#define SECONDS 5

#include <stdio.h>
#include <signal.h>

int number_of_alarms = 5;       /*  Set alarm counter.            */

void alarm_action(int);

main()
{
    signal(SIGALRM, alarm_action); /*  Establish a signal handler. */
                                   /*  to catch the SIGALRM signal.*/

    alarm(SECONDS);     /* Set alarm clock for 5 seconds. */

    pause();    /*  Suspend the process until     *
                 *  the signal is received.       */
}

void alarm_action(int x)
{
    printf("\t<%d\007>", number_of_alarms); /*  Print the value of  */
                                            /*  the alarm counter.  */

    signal(SIGALRM, alarm_action);      /*  Reset the signal.       */

    alarm(SECONDS);     /*  Set the alarm clock.      */

    if (--number_of_alarms)     /*  Decrement alarm counter.  */
        pause();
}