10 12

    Hi friend, some interesting came today. see following.
exit.c
#include
#include
#include
#include

int main( int argc, char **argv, char **environ )
{
    pid_t    pid;

    if( 0 > ( pid = fork() ) )
    {
        printf( "fork error!\n" );

        return( false );
    }
    else
    {
        if( pid > 0 )
        {
            printf( "parent pid is %d\n", getpid() );

            exit( EXIT_SUCCESS );
        }

//      sleep( 1 );

        printf( "init pid is %d\n", getppid() );
    }

    return( false );
}
print result:
init pid is 20999
parent pid is 20999

when i turn exit() to _exit()，result is following:
parent pid is 21244
init pid is 1

theory：
1， exit() can do something extra, like clear buffer.
2,  Function _exit() is faster than exit(). _exit() do nothing when it is called.

It is so interesting, isn't it!!!

In fact, If u want to know the basic theory, you should study the gnu/linux source!