commands/who/who.c

   1 /*      who 1.5 - tell who is currently logged in       Author: Kees J. Bot
   2  *                                                              9 Jul 1989
   3  */
   4 #define nil 0
   5 #include <sys/types.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <sys/stat.h>
  10 #include <utmp.h>
  11 #include <time.h>
  12 #include <string.h>
  13 #include <paths.h>
  14
  15 char PATH_UTMP[] = _PATH_UTMP;
  16
  17 char day[] = "SunMonTueWedThuFriSat";
  18 char month[] = "JanFebMarAprMayJunJulAugSepOctNovDec";
  19
  20 int main(int argc, char **argv)
  21 {
  22         char *tmp= PATH_UTMP;
  23         FILE *f;
  24         struct utmp ut;
  25         struct tm *tm;
  26         int slot, wtmp= 0, once= 0;
  27
  28         if (argc > 3) {
  29                 fprintf(stderr, "Usage: who <account-file>  |  who am i\n");
  30                 exit(1);
  31         }
  32         if (argc == 2) {
  33                 tmp= argv[1];
  34                 wtmp= 1;
  35         }
  36
  37         if ((f= fopen(tmp, "r")) == nil) {
  38                 fprintf(stderr, "who: can't open %s\n", tmp);
  39                 exit(1);
  40         }
  41         if (argc == 3) {
  42                 if ((slot= ttyslot()) < 0) {
  43                         fprintf(stderr, "who: no access to terminal.\n");
  44                         exit(1);
  45                 }
  46                 fseek(f, (off_t) sizeof(ut) * slot, 0);
  47                 once= 1;
  48         }
  49
  50         while (fread((char *) &ut, sizeof(ut), 1, f) == 1) {
  51                 if (!wtmp && ut.ut_name[0] == 0) continue;
  52
  53                 tm= localtime(&ut.ut_time);
  54
  55                 printf("%-9.8s %-9.8s %.3s %.3s %2d %02d:%02d",
  56                         ut.ut_name,
  57                         ut.ut_line,
  58                         day + (3 * tm->tm_wday),
  59                         month + (3 * tm->tm_mon),
  60                         tm->tm_mday,
  61                         tm->tm_hour,
  62                         tm->tm_min
  63                 );
  64
  65                 if (ut.ut_host[0] != 0) printf("  (%.*s)",
  66                                 (int) sizeof(ut.ut_host), ut.ut_host);
  67
  68                 printf("\n");
  69                 if (once) break;
  70         }
  71         exit(0);
  72 }