who1.c

#include <stdio.h>

#include <utmp.h>

#include <fcntl.h>

#include <unistd.h>

#define SHOWHOST

int main()

{

struct utmp current_record;

int utmpfd;

int reclen = sizeof(current_record);

if ((utmpfd = open(UTMP_FILE, O_RDONLY)) == -1)

{

perror(UTMP_FILE);

exit(1);

}

while (read(utmpfd, &current_record, reclen) == reclen)

show_info(&current_record);

close(utmpfd);

return 0;

}

show_info(struct utmp * utbufp)

{

printf("%-8.8s ", utbufp->ut_name);

printf("%-8.8s ", utbufp->ut_line);

printf("%10ld ",utbufp->ut_time);

#ifdef SHOWHOST

printf("(%s)",utbufp->ut_host);

#endif

printf("\n");

}