man/journal-iterate-wait.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <systemd/sd-journal.h>
   4
   5 int main(int argc, char *argv[]) {
   6   int r;
   7   sd_journal *j;
   8   r = sd_journal_open(&j, SD_JOURNAL_LOCAL_ONLY);
   9   if (r < 0) {
  10     fprintf(stderr, "Failed to open journal: %s\n", strerror(-r));
  11     return 1;
  12   }
  13   for (;;)  {
  14     const void *d;
  15     size_t l;
  16     r = sd_journal_next(j);
  17     if (r < 0) {
  18       fprintf(stderr, "Failed to iterate to next entry: %s\n", strerror(-r));
  19       break;
  20     }
  21     if (r == 0) {
  22       /* Reached the end, let's wait for changes, and try again */
  23       r = sd_journal_wait(j, (uint64_t) -1);
  24       if (r < 0) {
  25         fprintf(stderr, "Failed to wait for changes: %s\n", strerror(-r));
  26         break;
  27       }
  28       continue;
  29     }
  30     r = sd_journal_get_data(j, "MESSAGE", &d, &l);
  31     if (r < 0) {
  32       fprintf(stderr, "Failed to read message field: %s\n", strerror(-r));
  33       continue;
  34     }
  35     printf("%.*s\n", (int) l, (const char*) d);
  36   }
  37   sd_journal_close(j);
  38   return 0;
  39 }