Uptime is a measure of the time a machine, typically a computer, has been working and available. Uptime is the opposite of downtime.
Htop adds an exclamation mark when uptime is bigger than 100 days
It is often used as a measure of computer operating system reliability or stability, in that this time represents the time a computer can be left unattended without crashing, or needing to be rebooted for administrative or maintenance purposes.[citation needed]
Conversely, long uptime may indicate negligence, because some critical updates can require reboots on some platforms.[1]
Records
In 2005, Novell reported a server with a 6 year uptime.[2][3] Although that might sound unusual, that is actually common when servers are maintained under an industrial context and host critical applications such as banking systems.
Netcraft maintains the uptime records for many thousands of web hosting computers.[4]
An Amiga computer at a Hungarian television channel is reported having 16 years of uptime. The computer runs the channel's Teletext.[5]
Determining system uptime
Microsoft Windows
Using systeminfo
Users of Windows XP Professional, Windows Server 2003 and Windows Vista systems can type systeminfo at the Command Prompt to display all system information, including the System Up Time.[6]
C:\> systeminfo | findstr "Time:"System Up Time: 0 Days, 8 Hours, 7 Minutes, 19 Seconds
Note: Windows Vista Business 64-bit and Windows 7 do not return a "System Up Time" but "System Boot Time" instead. Also note that the exact text and date format is dependent of the language and locale Windows is running.
Note:Windows 7's "System Boot Time" is not a reliable indicator of boot time. It does not take into account the time spent in sleep or hibernation mode. Hence, the boot time drifts forward every time the computer is left in sleep or hibernate mode.
Using net statistics server/workstation
C:\> net statistics workstation | findstr "since"Server Statistics for \COMPUTERNAME Statistics since 8/31/2009 8:52:29 PM
The line that start with "Statistics since ..." provides the time that the server was up from. The command "net stats srv" is shorthand for "net statistics server."[7] The exact text and date format is dependent of the language and locale Windows is running.
Using Uptime.exe
Microsoft has also provided a downloadable Uptime.exe utility:
C:\> UptimeSYSTEMNAME has been up for: 2 day(s), 4 hour(s), 24 minute(s), 47 second(s)
Using WMI
Uptime can also be determined via Windows Management Instrumentation from the command-line with WMIC:
C:\> wmic os get lastbootuptimeLastBootUpTime201105081 61751.822066+060
The timestamp is in the format yyyymmddhhmmss.nnn, so this is a computer that last booted up on 8 May 2011 at 16:17:51.822. WMI can also be used to find the boot time of remote computers as well (Windows permissions allowing), for example with WMIC:
C:\> wmic /node:"my-server" os get lastbootuptimeLastBootUpTime201012191 41712.462006+060
The text "LastBootUpTime" and the timestamp format are always the same regardless of the language and locale, Windows is running.
WMI can also be used via a programming language such as VBScript or Powershell[8][9]
Using Windows Task Manager
Users of Windows Vista and Windows 7 can see uptime in Windows Task Manager under the tab Performance.
Linux
Using uptime
Users of Linux systems can use the uptime utility (uptime(1) – Linux User Commands Manual) to get the uptime, together with the current time, the number of users and load averages for the past 1, 5 and 15 minute intervals:
$ uptime 18:17:07 up 68 days, 3:57, 6 users, load average: 0.16, 0.07, 0.06
Using /proc/uptime
Shows how long the system has been on since it was last restarted:
$ cat /proc/uptime 350735.47 234388.90
The first number is the total number of seconds the system has been up. The second number is how much of that time the machine has spent idle, in seconds.[10] On multi core systems (and some linux versions) the second number is the sum of the idle time accumulated by each CPU.[11]
BSD
Using uptime
Like Linux, BSD-based operating systems such as FreeBSD and Mac OS X also have the uptime command (See uptime(1) – FreeBSD General Commands Manual).
Using sysctl
There is also a method of using sysctl to call the system's last boot time:[12]
$ sysctl kern.boottimekern.boottime: { sec = 1271934886, usec = 667779 } Thu Apr 22 12:14:46 2010 OpenVMS
Users of OpenVMS systems can type show system at the command prompt.[13]
$ show system/noprocessOpenVMS V7.3-2 on node JACK 29-JAN-2008 16:32:04.67 Uptime 894 22:28:52
This shows the uptime as days then hours:minutes:seconds.
External Uptime Measuring
There are a many external services which can be used to monitor the uptime and downtime as well as availability of a service or a host. Some examples:
See also
References
