SIGCHLD

/* waitdemo2.c - shows how parent gets child status
 */
 
#include    <stdio.h>
 
#define DELAY   5
 
main()
{
    int  newpid;
    void child_code(), parent_code();
 
    printf("before: mypid is %d\n", getpid());
 
    if ( (newpid = fork()) == -1 )
        perror("fork");
    else if ( newpid == 0 )
        child_code(DELAY);
    else
        parent_code(newpid);
}
/*
 * new process takes a nap and then exits
 */
void child_code(int delay)
{
    printf("child %d here. will sleep for %d seconds\n", getpid(), delay);
    sleep(delay);
    printf("child done. about to exit\n");
    exit(17);
}
/*
 * parent waits for child then prints a message
 */
void parent_code(int childpid)
{
    int wait_rv;        /* return value from wait() */
    int child_status;
    int high_8, low_7, bit_7;
 
    wait_rv = wait(&child_status);
    printf("done waiting for %d. Wait returned: %d\n", childpid, wait_rv);
 
    high_8 = child_status >> 8;     /* 1111 1111 0000 0000 */
    low_7  = child_status & 0x7F;   /* 0000 0000 0111 1111 */
    bit_7  = child_status & 0x80;   /* 0000 0000 1000 0000 */
    printf("status: exit=%d, sig=%d, core=%d\n", high_8, low_7, bit_7);
}