How to reset pointer of getutent()

Question

Following is the final code I was working on. I can sleep and show again other messages with sleep() but I can't print what I originally wanted which is inside 2nd while loop. As far as I tested, while((ptr=getutent()) != NULL) would be the problem but I don't know how to solve. I would really appreciate if anyone can help me. Thanks

Note: The program is showing current login user for every 5 seconds until user stop with Ctrl+c.

#include <utmp.h>
#include <pwd.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main(void)
{
    struct utmp *ptr;
    struct passwd *pwd;

    while(1)
    {

        while((ptr=getutent()) != NULL)
        {
            if(ptr->ut_type==USER_PROCESS)
            {
                pwd=getpwnam(ptr->ut_user);      
                printf("USERNAME = %s | ID = %d | GID = %d | ",p
tr->ut_user,pwd->pw_uid,pwd->pw_gid);
                printf("HomeDir = %s | HOST = %s\n",pwd->pw_dir,
ptr->ut_host);
            }
        }

        sleep(3);
        fflush(stdout);
    }

}

Answer 1

You want to use setutent() to set the file pointer back to the beginning of the utmp file.