How to get System UpTime using C program ?

D M Mehta · 02-25-2004, 12:58 AM

How do we get the system up time using C programming in Linux ??
i.e how to get the time when the system started using C Program.??

Tinkster · 02-25-2004, 01:47 AM

This is how GNU's coreutils
uptime does it

Code:

  fp = fopen ("/proc/uptime", "r");
  if (fp != NULL)
    {
      char buf[BUFSIZ];
      int res;
      char *b = fgets (buf, BUFSIZ, fp);
      if (b == buf)
        {
          /* The following sscanf must use the C locale.  */
          setlocale (LC_NUMERIC, "C");
          res = sscanf (buf, "%lf", &upsecs);
          setlocale (LC_NUMERIC, "");
          if (res == 1)
            uptime = (time_t) upsecs;
        }

      fclose (fp);
    }

:)

Cheers,
Tink