Does anyone know what's the meaning of my last command?

reboot   system boot  2.6.32-431.11.2. Sat May 28 15:06 - 05:01 (1+13:54)
reboot   system boot  2.6.32-431.11.2. Sat May 28 05:03 - 05:01 (1+23:58)

Seems the reboot was happened twice at one day and since the last column is indicated the length of the system started, it can't happened for the first line that shows the system had started up for 1 days and 13 hrs since the previous reboot was 5:03 at the same day!

BTW, what's the mean of the "05:01" column?


last lists the last logins which include system boot because all process groups (sessions) generate an entry in the session file and the first process (init) creates the first process group while booting. The last column in the output represents the whole system's session duration in between the different boots.

The only exception I know that can cause this discrepancy is a time or date change.

The "05:01" represents the session logout time. You can use the -F parameter to see full time listing which is a bit clearer.

  • I'm almost willing to bet that the date/time was changed during that day! – Julie Pelletier May 30 '16 at 4:37
  • Thanks @Juile I added the -F parameter and now it's showing "Mon May 30 06:55:46 2016" instead. It doesn't make any connections with the "05:01", that's strange. – NeilWang May 30 '16 at 6:00
  • @Juile I've figured it out, it keeps changing, it should be the current time because it belongs to the "still logged in" column. How can that be possible when the reboot keeps logging in the system? – NeilWang May 30 '16 at 6:07
  • I updated my answer to give the more technical reason. – Julie Pelletier May 30 '16 at 6:25
  • Good to know. So the first row of the reboot represents the system up time currently. However in my case, both of those two lines changed at the same the time. – NeilWang May 30 '16 at 6:39

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