Windows Task Scheduler: Difference between revisions

Revision as of 08:45, 18 August 2021

Revision as of 09:13, 11 September 2021

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| genre = [[Windows service]]

}}

'''Task Scheduler''' is(formerly a'''Scheduled componentTasks''')<ref ofname=":0" [[Microsoft/> Windows]],is including the latest versiona [[Windowsjob 10scheduler]],<ref>{{cite book|author1-last=Leonhard|author1-first=Woody|author2-last=Rusen|author2-first=Ciprian|year=2021|title=Windows 10 All-in-One For Dummies|publisher=[[JohnMicrosoft Wiley & SonsWindows]]|isbn=978-1119680574}}</ref> that provides the ability to schedule the launch oflaunches [[computer program]]s or scripts at pre-defined times or after specified time intervals: [[job scheduling]] (task scheduling).<ref>{{Cite web|title=Keep your Windows desktop in shape with Task Scheduler|work=[[TechRepublic]]|date=2002-01-04|url=https://www.techrepublic.com/article/keep-your-windows-desktop-in-shape-with-task-scheduler/}}</ref><ref>{{Cite web|title=What is Task Scheduler?|work=Computer Hope|date=2020-11-30|url=https://www.computerhope.com/jargon/t/tasksced.htm}}</ref> ItMicrosoft isintroduced implementedthis component in in the [[Microsoft Plus!]] for [[Windows 95]] as a''System Agent.''<ref>{{cite web|author=Al Fasoltd|date=March 29, 1998|title=Windows 98: Stable and fast, as well as 'new and improved'|url=http://www.technofileonline.com/texts/tec032998.html|access-date=2007-10-06|publisher=The Syracuse Newspapers}}</ref> Its core component is an eponymous [[Windows service]].<ref name="Mueller-2010">{{cite book|author-first=John Paul|author-last=Mueller|year=2010|title=Windows Command Line Administration Instant Reference|publisher=[[John Wiley & Sons]]|isbn=978-0470930908}}</ref> andThe wasWindows firstTask introducedScheduler ininfrastructure is the [[Microsoft Plus!]]basis for the [[Windows 95PowerShell]] asscheduled ''Systemjobs Agent''feature introduced with PowerShell v3.<ref>{{cite webbook|author-last=Warner|author-first=Timothy L.|year=2015|title=Sams Teach Yourself Windows PowerShell in 24 Hours|publisher=[[Sams Publishing]]|isbn=978-0134049359}}</ref>

| url = http://www.technofileonline.com/texts/tec032998.html

| title = Windows 98: Stable and fast, as well as 'new and improved'

| author = Al Fasoltd

| publisher = The Syracuse Newspapers

| date = March 29, 1998

| access-date = 2007-10-06

}}</ref> but was renamed to ''Task Scheduler'' in [[Internet Explorer 4.0]] and [[Windows 98]]. The [[Windows Event Log]] service must be running before the Task Scheduler starts up. The Windows Task Scheduler infrastructure is the basis for the [[Windows PowerShell]] scheduled jobs feature introduced with PowerShell v3.<ref>{{cite book|author-last=Warner|author-first=Timothy L.|year=2015|title=Sams Teach Yourself Windows PowerShell in 24 Hours|publisher=[[Sams Publishing]]|isbn=978-0134049359}}</ref>

Task Scheduler can be compared to [[cron]] or [[anacron]] on [[Unix-like]] [[operating system]]s. This service should not be confused with the [[Scheduling (computing)#Windows|scheduler]], which is a core component of the OS [[kernel (computing)|kernel]] that allocates [[CPU]] resources to processes already running.

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| work = [[MSDN]]

| publisher = [[Microsoft]]

}}</ref> It runs as a [[Windows Service]], and the task definitions and schedules are stored in [[Binary file|binary]] <code>.job</code> files. Tasks are manipulated directly by manipulating the <code>.job</code> files. Each task corresponds to single action. On [[Windows 95]] (with [[Internet Explorer 4.0]] or later), [[Windows 98]] and [[Windows Me]], the Task Scheduler runs as an ordinary program, <code>mstask.exe</code>. It also displays a status icon in the notification area on Windows 95 and Windows 98 and runs as a hidden service on Windows Me, but can be made to show a tray icon.<ref name=":0">{{cite web|url=http://support.microsoft.com/kb/272962|title=How to Enable the Scheduled Tasks Icon in Windows Me|date=January 29, 2007|work=Support|publisher=[[Microsoft]]|url-status=dead|archive-url=https://web.archive.org/web/20080130185556/http://support.microsoft.com/kb/272962|archive-date=January 30, 2008}}</ref> Computer programs and [[Scripting language|scripts]] can access the service through six [[Component Object Model|COM]] [[Interface (computing)|interfaces]].<ref>{{Cite web|url = https://msdn.microsoft.com/en-us/library/windows/desktop/aa383581%28v=vs.85%29.aspx|title = Task Scheduler 1.0 Interfaces|access-date = 30 May 2014|website = [[MSDN]]|publisher = [[Microsoft]]}}</ref> Microsoft provides a scheduling agent DLL, a sample [[VBScript]] and a configuration file to automate Task Scheduler.<ref>{{cite web|url=http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=601d75e2-f907-4e51-ad88-adb818df1d27|title=Task Scheduler Using VBScript|work=Download Center|publisher=[[Microsoft]]|date=March 22, 2004|url-status=dead|archive-url=https://web.archive.org/web/20060504033359/http://www.microsoft.com/downloads/details.aspx?FamilyID=601d75e2-f907-4e51-ad88-adb818df1d27&displaylang=en|archive-date=May 4, 2006}}</ref>

In addition to the graphical user interface for Task Scheduler in [[Control Panel (Windows)|Control Panel]], Windows provides two command-line tools for managing scheduled task: <code>[[at (command)|at.exe]]</code> (deprecated)<ref>{{cite web|url=https://www.computerhope.com/at.htm|title=MS-DOS and Windows command line at command|access-date=7 March 2021|website=Computer Hope}}</ref> and <code>schtasks.exe</code>.<ref name="Mueller-2010" /><ref>{{cite web|title=Schtasks|url=https://technet.microsoft.com/en-us/library/bb490996.aspx|work=[[Microsoft TechNet]]|publisher=[[Microsoft]]|access-date=18 May 2014}}</ref><ref>{{cite web|title=At|url=https://technet.microsoft.com/en-us/library/bb490866.aspx|work=[[Microsoft TechNet]]|publisher=[[Microsoft]]|access-date=18 May 2014}}</ref> However, <code>at.exe</code> cannot access tasks created or modified by Control Panel or <code>schtasks.exe</code>.<ref>{{Cite web|url = http://support.microsoft.com/kb/313565|title = How To Use the AT Command to Schedule Tasks|date = 30 October 2006|website = Support|publisher = [[Microsoft]]}}</ref> Also, tasks created with <code>at.exe </code>are not interactive by default; interactivity needs to be explicitly requested. The binary ".job" files which the AT command produces are stored in the %WINDIR%\Tasks directory.<ref>{{cite book|author1-first=Dave|author1-last=Kleiman|author2-first=Laura E|author2-last=Hunter|year=2006|title=Winternals Defragmentation, Recovery, and Administration Field Guide|publisher=[[Elsevier]]|isbn=978-0080489872}}</ref><ref>{{Cite web|url = http://support.microsoft.com/kb/121562/EN-US|title = Applications Started with AT Are Not Interactive|date = 20 February 2007|website = Support|publisher = [[Microsoft]]|url-status=dead|archive-url=https://web.archive.org/web/20041029024318/http://support.microsoft.com/kb/121562/EN-US/|archive-date=October 29, 2004}}</ref>

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==Bugs==

On Windows 2000 and Windows XP, tasks assigned to run with SYSTEM privileges do not function when thea computer is prepared for [[disk imaging]] with <code>the [[sysprep]]</code> utility, it cannot run tasks configured to run in the context of the [[Superuser|SYSTEM account]]. Sysprep changes the [[security identifier]] (SID) to avoid duplication but does not update scheduled tasks to use the new SID. Consequently, allthe SYSTEM scheduledaffected tasks fail to run on the imaged computers. There is no solution for this problem but one may reschedule the affected tasks to work around the issue.<ref>{{cite web|title=Scheduled tasks may not start if you used a System Preparation image to install Windows XP or Windows 2000|url=http://support.microsoft.com/kb/313111|work=Support|publisher=[[Microsoft]]|access-date=19 May 2012|date=1 July 2004|url-status=dead|archive-url=https://web.archive.org/web/20080926011921/http://support.microsoft.com/kb/313111|archive-date=26 September 2008}}</ref>

On Windows Vista or Windows Server 2008, where Service Pack 2 is not installed,<!-- To source checkers: You need to expand tables in File information section to reveal this information --> the next execution time displayed in Task Scheduler may be wrong. Microsoft issued a [[hotfix]] to remedy this issue.<ref>{{cite web|date=15 October 2008|title=The value in the Next Run Time field in Task Scheduler is incorrect in Windows Vista and in Windows Server 2008|url=http://support.microsoft.com/kb/950035|workurl-status=Supportlive|publisherarchive-url=[[Microsoft]]https://web.archive.org/web/20081211175231/http://support.microsoft.com/kb/950035|accessarchive-date=1911 MayDecember 20122008|datework=15 October 2008Support|publisher=[[Microsoft]]}}

</ref>

On Windows Vista, 7, 2008, and 2008 R2: The [[Microsoft Management Console|MMC]] Component says that the system is running "Task Scheduler 1.0" when in fact it is running 2.0, this is a trivial bug so it wasn't noticed, and is likely due to the re-write of the task scheduler. The version has been corrected to 2.0 in Windows 8 and in 2012.

==See also==

*[[cron]], job scheduler for Unix-like operating systems

*[[Job scheduling]]

*[[cron]]

==References==