F-ckin Leap Seconds, how do they work?

Tue Jul 3 21:54:59 UTC 2012

On Jul 3, 2012, at 5:06 PM, Peter Lothberg wrote:

> 
> 
> On one of my BSD boxes. /usr/src/share/zoneinfo/leapseconds, I see no
> "-"

No, but they're allowed; see Figure 9 of RFC 5905:

   LI Leap Indicator (leap): 2-bit integer warning of an impending leap
   second to be inserted or deleted in the last minute of the current
   month with values defined in Figure 9.

           +-------+----------------------------------------+
           | Value | Meaning                                |
           +-------+----------------------------------------+
           | 0     | no warning                             |
           | 1     | last minute of the day has 61 seconds  |
           | 2     | last minute of the day has 59 seconds  |
           | 3     | unknown (clock unsynchronized)         |
           +-------+----------------------------------------+

                         Figure 9: Leap Indicator

		--Steve Bellovin, https://www.cs.columbia.edu/~smb