| DMESG(8) | System Manager's Manual | DMESG(8) | 
dmesg —
| dmesg | [ -dTt] [-Mcore] [-Nsystem] | 
dmesg displays the contents of the system message
  buffer.
The options are as follows:
-d-t
      only the deltas are shown.-M-N-T-tThe system message buffer is a circular buffer of a fixed size. If
    the buffer has been filled, the first line of the
    dmesg output may not be complete. The size of the
    message buffer is configurable at compile-time on most systems with the
    MSGBUFSIZE kernel option. Look for
    MSGBUFSIZE in
    options(4) for details.
dmesg command appeared in
  3.0BSD.
-T option will report nonsense when displaying lines
  from the message buffer that were not added by the current running kernel.
When -TT is used, the duration is always
    given with maximum units of hours, even when the number of hours is in the
    hundreds, thousands, or more. This is because converting hours to days, over
    periods when “time skips” occur, such as summer time beginning
    or ending, is not trivial. A duration of 26 hours might be 1D3H or 1D1H at
    such events, rather than the usual 1D2H, and when a time zone alters its
    offset, even more complex calculations are needed. None of those
    calculations are done (even to account for sub-hour time zone shifts), the
    duration indicated is always calculated by simple division of seconds by 60
    to produce minutes, and again to produce hours. Most of the time [!]
    this is correct.
| October 30, 2018 | NetBSD 9.4 |