Thread: Procesees, fork(), wait() and exec()

Trying to learn about processes and such in UNIX.
I wrote this little thing to help me try to understand.

Code:

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/resource.h>

void child( char *command, char *arg[] );

int main()
{
    char *arg[3], *tm;
    char *command = "ls";
    struct rusage *data;
    
    int pid, w_child;
    
    pid = fork();
    
    if( pid == 0 )
        child( command, arg);
    else if( pid > 0 )
        w_child = wait3(NULL, 0, data);
    
    /* HOW do i get access to statistics from wait3()
    tm = ctime((data.ru_utime)->tv_sec);
    printf( "%s\n", tm);
    */
    
    printf( "END: you should see 'ls -l'.\n" );
    printf( "The parent pid is: %d\n", getpid() );
    printf( "The child pid was: %d\n", w_child );
    
    return 0;
}

void child( char *command, char *arg[] )
{
    arg[0] = "";
    arg[1] = "-l";
    arg[2] = 0;
    
    execvp( command, arg );
}

Can someone help me with the correct way to access the data from the rusage struct. I would like to be able to generate a line which shows the system, user and real time used by the process, but am confused on how to get data.

Any pointers (sorry, bad joke) would be appreciated.

Thanks for the quick reply, just what I needed!