Starts a Windows PowerShell background job.
Syntax
Start-Job [-ScriptBlock] <scriptblock> [[-InitializationScript] <scriptblock>] [-ArgumentList <Object[]>] [-Authentication {<Default> | <Basic> | <Negotiate> | <NegotiateWithImplicitCredential> | <Credssp> | <Digest> | <Kerberos>}] [-Credential <PSCredential>] [-InputObject <psobject>] [-Name <string>] [-RunAs32] [<CommonParameters>]
Start-Job [[-FilePath] <string>] [[-InitializationScript] <scriptblock>] [-ArgumentList <Object[]>] [-Authentication {<Default> | <Basic> | <Negotiate> | <NegotiateWithImplicitCredential> | <Credssp> | <Digest> | <Kerberos>}] [-Credential <PSCredential>] [-InputObject <psobject>] [-Name <string>] [-RunAs32] [<CommonParameters>]
Description
The Start-Job cmdlet starts a Windows PowerShell background job on the local computer.
A Windows PowerShell background job runs a command "in the background" without interacting with the current session. When you start a background job, a job object is returned immediately, even if the job takes an extended time to complete. You can continue to work in the session without interruption while the job runs.
The job object contains useful information about the job, but it does not contain the job results. When the job completes, use the Receive-Job cmdlet to get the results of the job. For more information about background jobs, see about_Jobs.
To run a background job on a remote computer, use the AsJob parameter that is available on many cmdlets, or use the Invoke-Command cmdlet to run a Start-Job command on the remote computer. For more information, see about_Remote_Jobs.
Parameters
-ArgumentList <Object[]>
Specifies the arguments (parameter values) for the script that is specified by the FilePath parameter.
Because all of the values that follow the ArgumentList parameter name are interpreted as being values of ArgumentList, the ArgumentList parameter should be the last parameter in the command.
|
Required? |
false |
|
Position? |
named |
|
Default Value |
none |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
-Authentication <AuthenticationMechanism>
Specifies the mechanism that is used to authenticate the user's credentials. Valid values are Default, Basic, Credssp, Digest, Kerberos, Negotiate, and NegotiateWithImplicitCredential. The default value is Default.
CredSSP authentication is available only in Windows Vista, Windows Server 2008, and later versions of Windows.
For information about the values of this parameter, see the description of the System.Management.Automation.Runspaces.AuthenticationMechanism enumeration in MSDN.
CAUTION: Credential Security Service Provider (CredSSP) authentication, in which the user's credentials are passed to a remote computer to be authenticated, is designed for commands that require authentication on more than one resource, such as accessing a remote network share. This mechanism increases the security risk of the remote operation. If the remote computer is compromised, the credentials that are passed to it can be used to control the network session.
|
Required? |
false |
|
Position? |
named |
|
Default Value |
none |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
-Credential <PSCredential>
Specifies a user account that has permission to perform this action. The default is the current user.
Type a user name, such as "User01" or "Domain01\User01", or enter a PSCredential object, such as one from the Get-Credential cmdlet.
|
Required? |
false |
|
Position? |
named |
|
Default Value |
Current user |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
-FilePath <string>
Runs the specified local script as a background job. Enter the path and file name of the script or pipe a script path to Start-Job. The script must reside on the local computer or in a directory that the local computer can access.
When you use this parameter, Windows PowerShell converts the contents of the specified script file to a script block and runs the script block as a background job.
|
Required? |
false |
|
Position? |
1 |
|
Default Value |
none |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
-InitializationScript <scriptblock>
Specifies commands that run before the job starts. Enclose the commands in braces ( { } ) to create a script block.
Use this parameter to prepare the session in which the job runs. For example, you can use it to add functions, snap-ins, and modules to the session.
|
Required? |
false |
|
Position? |
2 |
|
Default Value |
None |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
-InputObject <psobject>
Specifies input to the command. Enter a variable that contains the objects, or type a command or expression that generates the objects.
In the value of the ScriptBlock parameter, use the $input automatic variable to represent the input objects.
|
Required? |
false |
|
Position? |
named |
|
Default Value |
none |
|
Accept Pipeline Input? |
true (ByValue) |
|
Accept Wildcard Characters? |
false |
-Name <string>
Specifies a friendly name for the new job. You can use the name to identify the job to other job cmdlets, such as Stop-Job.
The default friendly name is Job#, where "#" is an ordinal number that is incremented for each job.
|
Required? |
false |
|
Position? |
named |
|
Default Value |
Job<number> |
|
Accept Pipeline Input? |
true (ByPropertyName) |
|
Accept Wildcard Characters? |
false |
-RunAs32
Runs the job in a 32-bit process.
Use this parameter to force the job to run in a 32-bit process on a 64-bit operating system.
|
Required? |
false |
|
Position? |
named |
|
Default Value |
False |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
-ScriptBlock <scriptblock>
Specifies the commands to run in the background job. Enclose the commands in braces ( { } ) to create a script block. This parameter is required.
|
Required? |
true |
|
Position? |
1 |
|
Default Value |
none |
|
Accept Pipeline Input? |
false |
|
Accept Wildcard Characters? |
false |
<CommonParameters>
This cmdlet supports the common parameters: -Verbose, -Debug, -ErrorAction, -ErrorVariable, -OutBuffer, and -OutVariable. For more information, see about_CommonParameters.
Inputs and Outputs
The input type is the type of the objects that you can pipe to the cmdlet. The return type is the type of the objects that the cmdlet returns.
|
Inputs |
System.String You can pipe a file path to Start-Job. |
|
Outputs |
System.Management.Automation.RemotingJob Start-Job returns an object that represents the job that it started. |
Notes
To run in the background, Start-Job runs in its own session within the current session. When you use the Invoke-Command cmdlet to run a Start-Job command in a session on a remote computer, Start-Job runs in a session within the remote session.
Example 1
C:\PS>start-job -scriptblock {get-process}
C:\PS> start-job -command "get-process"
Id Name State HasMoreData Location Command
--- ---- ----- ----------- -------- -------
1 Job1 Running True localhost get-process
Description
-----------
This command starts a background job that runs a Get-Process command. The command returns a job object with information about the job. The command prompt returns immediately so that you can work in the session while the job runs in the background.
Example 2
C:\PS>$jobWRM = invoke-command -computerName (get-content servers.txt) -scriptblock {get-service winrm} -jobname WinRM -throttlelimit 16 -AsJob
This command uses the Invoke-Command cmdlet and its AsJob parameter to start a background job that runs a "get-service winrm" command on numerous computers. Because the command is running on a server with substantial network traffic, the command uses the ThrottleLimit parameter of Invoke-Command to limit the number of concurrent commands to 16.
The command uses the ComputerName parameter to specify the computers on which the job runs. The value of the ComputerName parameter is a Get-Content command that gets the text in the Servers.txt file, a file of computer names in a domain.
The command uses the ScriptBlock parameter to specify the command and the JobName parameter to specify a friendly name for the job.
Example 3
C:\PS>$j = start-job -scriptblock {get-eventlog -log system} -credential domain01\user01
C:\PS> $j | format-list -property *
HasMoreData : True
StatusMessage :
Location : localhost
Command : get-eventlog -log system
JobStateInfo : Running
Finished : System.Threading.ManualResetEvent
InstanceId : 2d9d775f-63e0-4d48-b4bc-c05d0e177f34
Id : 1
Name : Job1
ChildJobs : {Job2}
Output : {}
Error : {}
Progress : {}
Verbose : {}
Debug : {}
Warning : {}
StateChanged :
C:\PS> $j.JobStateInfo.state
Completed
C:\PS> $results = receive-job -job $j
C:\PS> $results
Index Time Type Source EventID Message
----- ---- ---- ------ ------- -------
84366 Feb 18 19:20 Information Service Control M... 7036 The description...
84365 Feb 18 19:16 Information Service Control M... 7036 The description...
84364 Feb 18 19:10 Information Service Control M... 7036 The description...
...
Description
-----------
These commands manage a background job that gets all of the events from the System log in Event Viewer. The job runs on the local computer.
The first command uses the Start-Job cmdlet to start the job. It uses the Credential parameter to specify the user account of a user who has permission to run the job on the computer. Then it saves the job object that Start-Job returns in the $j variable.
At this point, you can resume your other work while the job completes.
The second command uses a pipeline operator (|) to pass the job object in $j to the Format-List cmdlet. The Format-List command uses the Property parameter with a value of all (*) to display all of the properties of the job object in a list.
The third command displays the value of the JobStateInfo property. This contains the status of the job.
The fourth command uses the Receive-Job cmdlet to get the results of the job. It stores the results in the $results variable.
The final command displays the contents of the $results variable.
Example 4
C:\PS>start-job -filepath c:\scripts\sample.ps1 This command runs the Sample.ps1 script as a background job.
Example 5
C:\PS>start-job -name WinRm -scriptblock {get-process winrm}
This command runs a background job that gets the WinRM process on the local computer. The command uses the ScriptBlock parameter to specify the command that runs in the background job. It uses the Name parameter to specify a friendly name for the new job.
Example 6
C:\PS>start-job -name GetMappingFiles -initializationScript {import-module MapFunctions} -scriptblock {Get-Map -name * | set-content D:\Maps.tif} -runAs32
This command starts a job that collects a large amount of data and saves it in a .tif file. The command uses the InitializationScript parameter to run a script block that imports a required module. It also uses the RunAs32 parameter to run the job in a 32-bit process even if the computer has a 64-bit operating system.
See Also