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about_Remote_Jobs

Updated: October 17, 2013

Applies To: Windows PowerShell 2.0, Windows PowerShell 3.0, Windows PowerShell 4.0

TOPIC
    about_Remote_Jobs

SHORT DESCRIPTION
    Describes how to run background jobs on remote computers.

DETAILED DESCRIPTION
    A background job is a command that runs asynchronously without interacting
    with the current session. The command prompt returns immediately, and you
    can continue to use the session while the job runs.

    By default, background jobs run on the local computer. However, you can 
    use several different procedures to run background jobs on remote 
    computers. 

    This topic explains how to run a background job on a remote computer. For
    information about how to run background jobs on a local computer, see 
    about_Jobs. For more information about background jobs, see 
    about_Job_Details.


 REMOTE BACKGROUND JOBS

    You can run background jobs on remote computers by using three different 
    methods. 

    -- Start an interactive session with a remote computer, and start a job 
       in the interactive session. The procedures are the same as running a 
       local job, although all actions are performed on the remote computer.

    -- Run a background job on a remote computer that returns its results to
       the local computer. Use this method when you want to collect the 
       results of background jobs and maintain them in a central location on
       the local computer.

    -- Run a background job on a remote computer that maintains its results
       on the remote computer. Use this method when the job data is more 
       securely maintained on the originating computer.   
   

 START A BACKGROUND JOB IN AN INTERACTIVE SESSION

    You can start an interactive session with a remote computer and then
    start a background job during the interactive session. For more 
    information about interactive sessions, see about_Remote, and
    see Enter-PSSession.

    The procedure for starting a background job in an interactive session is
    almost identical to the procedure for starting a background job on the 
    local computer. However, all of the operations occur on the remote 
    computer, not the local computer.


    STEP 1: ENTER-PSSESSION

    Use the Enter-PSSession cmdlet to start an interactive session with a 
    remote computer. You can use the ComputerName parameter of Enter-PSSession
    to establish a temporary connection for the interactive session. Or, you
    can use the Session parameter to run the interactive session in a Windows 
    PowerShell session (PSSession).  

    The following command starts an interactive session on the Server01 
    computer.
  
        C:\PS> Enter-PSSession -computername Server01

    The command prompt changes to show that you are now connected to the 
    Server01 computer.

        Server01\C:>


    STEP 2: START-JOB

    To start a background job in the session, use the Start-Job cmdlet.

    The following command runs a background job that gets the events in the
    Windows PowerShell event log on the Server01 computer. The Start-Job 
    cmdlet returns an object that represents the job. 

    This command saves the job object in the $job variable. 

        Server01\C:> $job = start-job -scriptblock {get-eventlog "Windows PowerShell"}
   
    While the job runs, you can use the interactive session to run other 
    commands, including other background jobs. However, you must keep the 
    interactive session open until the job is completed. If you end the 
    session, the job is interrupted, and the results are lost.



    STEP 3: GET-JOB

    To find out if the job is complete, display the value of the $job variable,
    or use the Get-Job cmdlet to get the job. The following command uses the
    Get-Job cmdlet to display the job.

        Server01\C:> get-job $job

        SessionId  Name  State      HasMoreData  Location   Command
        ---------  ----  -----      -----------  --------   -------
        1          Job1  Complete   True         localhost  get-eventlog "Windows PowerShell"
   
   
    The Get-Job output shows that job is running on the "localhost" computer
    because the job was started on and is running on the same computer (in 
    this case, Server01).
    


    STEP 4: RECEIVE-JOB

    To get the results of the job, use the Receive-Job cmdlet. You can display
    the results in the interactive session or save them to a file on the remote
    computer. The following command gets the results of the job in the $job 
    variable. The command uses the redirection operator (>) to save the results
    of the job in the PsLog.txt file on the Server01 computer.

        Server01\C:> receive-job $job > c:\logs\PsLog.txt



    STEP 5: EXIT-PSSESSION

    To end the interactive session, use the Exit-PSSession cmdlet. The command
    prompt changes to show that you are back in the original session on the
    local computer.

        Server01\C:> Exit-PSSession
        C:\PS>
         


    STEP 6: INVOKE-COMMAND: GET-CONTENT
     
    To view the contents of the PsLog.txt file on the Server01 computer at any
    time, start another interactive session, or run a remote command. This type
    of command is best run in a PSSession (a persistent connection) in case you
    want to use several commands to investigate and manage the data in the 
    PsLog.txt file. For more information about PSSessions, 
    see about_PSSessions.

    The following commands use the New-PSSession cmdlet to create a PSSession 
    that is connected to the Server01 computer, and they use the Invoke-Command
    cmdlet to run a Get-Content command in the PSSession to view the contents
    of the file.

        C:\PS> $s = new-pssession -computername Server01
        C:\PS> invoke-command -session $s -scriptblock {get-content c:\logs\pslog.txt}


       
 START A REMOTE JOB THAT RETURNS THE RESULTS TO THE LOCAL COMPUTER (ASJOB)

    To start a background job on a remote computer that returns the command
    results to the local computer, use the AsJob parameter of a cmdlet such
    as the Invoke-Command cmdlet. 

    When you use the AsJob parameter, the job object is actually created on
    the local computer even though the job runs on the remote computer. When
    the job is completed, the results are returned to the local computer. 

    You can use the cmdlets that contain the Job noun (the Job cmdlets) to
    manage any job created by any cmdlet. Many of the cmdlets that have
    AsJob parameters do not use Windows PowerShell remoting, so 
    you can use them even on computers that are not configured for 
    remoting and that do not meet the requirements for remoting.
 

    STEP 1: INVOKE-COMMAND -ASJOB

    The following command uses the AsJob parameter of Invoke-Command to start
    a background job on the Server01 computer. The job runs a Get-Eventlog 
    command that gets the events in the System log. You can use the JobName
    parameter to assign a display name to the job.

       invoke-command -computername Server01 -scriptblock {get-eventlog system} -asjob  

    The results of the command resemble the following sample output.


       SessionId   Name    State      HasMoreData     Location   Command
       ---------   ----    -----      -----------     --------   -------
       1           Job1    Running    True            Server01   get-eventlog system


    When the AsJob parameter is used, Invoke-Command returns the same type of
    job object that Start-Job returns. You can save the job object in a 
    variable, or you can use a Get-Job command to get the job.

    Note that the value of the Location property shows that the job ran on the
    Server01 computer.    


    STEP 2: GET-JOB

    To manage a job started by using the AsJob parameter of the Invoke-Command
    cmdlet, use the Job cmdlets. Because the job object that represents the 
    remote job is on the local computer, you do not need to run remote commands
    to manage the job.    

    To determine whether the job is complete, use a Get-Job command. The 
    following command gets all of the jobs that were started in the current
    session. 

        get-job

    Because the remote job was started in the current session, a local Get-Job
    command gets the job. The State property of the job object shows that the
    command was completed successfully.       
       
       SessionId   Name   State      HasMoreData     Location   Command
       ---------   ----   -----      -----------     --------   -------
       1           Job1   Completed  True            Server01   get-eventlog system



    STEP 3: RECEIVE-JOB

    To get the results of the job, use the Receive-Job cmdlet. Because the job
    results are automatically returned to the computer where the job object 
    resides, you can get the results with a local Receive-Job command.

    The following command uses the Receive-Job cmdlet to get the results of the
    job. It uses the session ID to identify the job. This command saves the job
    results in the $results variable. You can also redirect the results to a 
    file.

       $results = receive-job -id 1
    


 START A REMOTE JOB THAT KEEPS THE RESULTS ON THE REMOTE COMPUTER

    To start a background job on a remote computer that keeps the command 
    results on the remote computer, use the Invoke-Command cmdlet to run
    a Start-Job command on a remote computer. You can use this method to run
    background jobs on multiple computers.

    When you run a Start-Job command remotely, the job object is created on the
    remote computer, and the job results are maintained on the remote computer.
    From the perspective of the job, all operations are local. You are just
    running commands remotely to manage a local job on the remote computer.


    STEP 1: INVOKE-COMMAND START-JOB

    Use the Invoke-Command cmdlet to run a Start-Job command on a remote 
    computer. 

    This command requires a PSSession (a persistent connection). If you use
    the ComputerName parameter of Invoke-Command to establish a temporary
    connection, the Invoke-Command command is considered to be complete when
    the job object is returned. As a result, the temporary connection is 
    closed, and the job is canceled.
 
    The following command uses the New-PSSession cmdlet to create a PSSession 
    that is connected to the Server01 computer. The command saves the PSSession
    in the $s variable.

        $s = new-pssession -computername Server01


    The next command uses the Invoke-Command cmdlet to run a Start-Job command
    in the PSSession. The Start-Job command and the Get-Eventlog command are 
    enclosed in braces.

       invoke-command -session $s -scriptblock {start-job -scriptblock {get-eventlog system}}

    The results resemble the following sample output.


       Id       Name    State      HasMoreData     Location   Command
       --       ----    -----      -----------     --------   -------
       2        Job2    Running    True            Localhost  get-eventlog system


    When you run a Start-Job command remotely, Invoke-Command returns the same
    type of job object that Start-Job returns. You can save the job object in 
    a variable, or you can use a Get-Job command to get the job.

    Note that the value of the Location property shows that the job ran on the
    local computer, known as "LocalHost", even though the job ran on the 
    Server01 computer. Because the job object is created on the Server01 
    computer and the job runs on the same computer, it is considered to
    be a local background job.    


    STEP 2: INVOKE-COMMAND GET-JOB

    To manage a remote background job, use the Job cmdlets. Because the job 
    object is on the remote computer, you need to run remote commands to get,
    stop, wait for, or retrieve the job results.    

    To see if the job is complete, use an Invoke-Command command to run a 
    Get-Job command in the PSSession that is connected to the Server01 
    computer.

        invoke-command -session $s -scriptblock {get-job}

    The command returns a job object. The State property of the job object
    shows that the command was completed successfully.       
       

       SessionId       Name    State      HasMoreData     Location   Command
       ---------       ----    -----      -----------     --------   -------
       2               Job2    Completed  True            LocalHost   get-eventlog system


    STEP 3: INVOKE-COMMAND RECEIVE-JOB

    To get the results of the job, use the Invoke-Command cmdlet to run a 
    Receive-Job command in the PSSession that is connected to the Server01 
    computer.

    The following command uses the Receive-Job cmdlet to get the results of
    the job. It uses the session ID to identify the job. This command saves 
    the job results in the $results variable. It uses the Keep parameter of
    Receive-Job to keep the result in the job cache on the remote
    computer.

        $results = invoke-command -session $s -scriptblock {receive-job -sessionid 2 -keep}

    You can also redirect the results to a file on the local or remote 
    computer. The following command uses a redirection operator to save the
    results in a file on the Server01 computer.

        invoke-command -session $s -command {receive-job -sessionid 2 > c:\logs\pslog.txt}


SEE ALSO
    about_Jobs
    about_Job_Details
    about_Remote
    about_Remote_Variables
    Invoke-Command
    Start-Job
    Get-Job
    Wait-Job
    Stop-Job
    Remove-Job
    New-PSSession
    Enter-PSSession
    Exit-PSSession



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