uname.c

   1 /* `uname.c` - return system name
   2    Copyright (c) 2022, Alan Potteiger
   3    See `LICENSE` for copyright and license details */
   4
   5 #define _POSIX_C_SOURCE 200809L
   6
   7 #include <stdio.h>
   8 #include <unistd.h>
   9 #include <sys/utsname.h>
  10
  11 static const char *usage = {
  12         "usage: uname [-amnrsv]\n"
  13 };
  14
  15 int
  16 main(int argc, char *argv[])
  17 {
  18         struct utsname name;
  19         int m, n, r, s, v;
  20         char ch;
  21
  22         m = n = r = s = v = 0;
  23
  24         while ((ch = getopt(argc, argv, "amnrsv")) != -1) {
  25                 switch (ch) {
  26                 case 'a':
  27                         m = n = r = s = v = 1;
  28                         break;
  29                 case 'm':
  30                         m = 1;
  31                         break;
  32                 case 'n':
  33                         n = 1;
  34                         break;
  35                 case 'r':
  36                         r = 1;
  37                         break;
  38                 case 's':
  39                         s = 1;
  40                         break;
  41                 case 'v':
  42                         v = 1;
  43                         break;
  44                 case '?':
  45                 default:
  46                         fputs(usage, stderr);
  47                         return 1;
  48                 }
  49         }
  50
  51         if (uname(&name) == -1) {
  52                 perror("uname");
  53                 return 1;
  54         }
  55
  56         if (!(m || n || r || s || v))
  57                 s = 1;
  58
  59         if (m && n && r && s && v) {
  60                 printf(
  61                         "%s %s %s %s %s\n",
  62                         name.sysname, name.nodename, name.release,
  63                         name.version, name.machine
  64                 );
  65
  66                 return 0;
  67         }
  68
  69         /* I think this could be done better or more efficiently. I'm tired
  70            as hell though. I'll revisit this at some point */
  71         if (s)
  72                 printf("%s ", name.sysname);
  73         if (n)
  74                 printf("%s ", name.nodename);
  75         if (r)
  76                 printf("%s ", name.release);
  77         if (v)
  78                 printf("%s ", name.version);
  79         if (m)
  80                 printf("%s ", name.machine);
  81
  82         puts("");
  83
  84         return 0;
  85 }
  86