Re: vmstat -s "boot time" Redhat Linux
From: Yong Huang <yong321_at_yahoo.com>
Date: Sat, 14 Nov 2009 09:11:40 -0800 (PST)
Message-ID: <633916.1202.qm_at_web80608.mail.mud.yahoo.com>
> That is the actual time in seconds since the epoch (unix time) that the
> machine was started. It's stored in /proc/stat, and vmstat just grabs the
> raw value and displays it with a slightly better label (it's btime in
> /proc/stat).
Date: Sat, 14 Nov 2009 09:11:40 -0800 (PST)
Message-ID: <633916.1202.qm_at_web80608.mail.mud.yahoo.com>
> That is the actual time in seconds since the epoch (unix time) that the
> machine was started. It's stored in /proc/stat, and vmstat just grabs the
> raw value and displays it with a slightly better label (it's btime in
> /proc/stat).
Matthew is right. On Linux, `who -b' shows the time the system came up:
$ who -b
system boot 2009-10-19 16:53
You can use this to verify (month starts with 0):
$ perl -e 'use Time::Local; print timelocal(0, 53, 16, 19, 9, 2009)'
1255989180$
$
$ vmstat -s | grep boot
1255989111 boot time
I got 69 seconds' difference mostly because (I think) /var/run/utmp has a slightly different bootup time than /proc/stat. That is, /proc/stat is populated earlier than /var/run/utmp. The difference would be larger if I assumed a non-zero second in my Perl one-liner for the time given by `who -b'.
Yong Huang
-- http://www.freelists.org/webpage/oracle-lReceived on Sat Nov 14 2009 - 11:11:40 CST