title: /proc/[pid]/cmdline file size
body: <p>i'm trying to get the filesize of the cmdline file in proc/[pid]. For example porc/1/cmdline. The file is not empty, it contains "/sbin/init". But i get file_size = 0.</p>
  
  <pre><code>int main(int argc, char **argv) {
      int file_size;
      FILE *file_cmd;
      file_cmd = fopen("/proc/1/cmdline", "r");
      if(file_cmd == NULL) {
          perror("proc/1/cmdline");
          exit(1);
      }else {
          if(fseek(file_cmd, 0L, SEEK_END)!=0) {
              perror("proc/1/cmdline");
              exit(1);
          }
          file_size = ftell(file_cmd);
      }
      printf("fs: %d\n",file_size);
      fclose(file_cmd);
      }
  </code></pre>
  
  <p>Regards</p>