Prof. Powershell

More Jobs

The -AsJob parameter offers an alternative approach to remoting, one that's more interactive.

• By Jeffery Hicks
• 07/21/2009

Last time I talked about running PowerShell commands as background jobs on your computer. The Start-Job cmdlet doesn't have a parameter that will create the job on a remote computer. Instead, you have two possibilities. First, you can create the remote job using Invoke-Command and retrieve the results locally. Or you can use an interactive remote session and use cmdlets that contain the new -AsJob parameter. When using this technique, job results stay on the remote computer until you retrieve them:

PS Y:\> invoke-command -ScriptBlock {dir $env:temp -recurse} -ComputerName Win2k801 -asJob

Id  Name  State    HasMoreData  Location  Command
--  ----  -----    -----------  --------  -------
3   Job3  Running  True         win2k801  dir $env:temp -recurse

In this example I've created a background job using a remote computer session to Win2K801. Later, I can check the job status:

PS Y:\> get-job -Name job3

Id  Name  State      HasMoreData  Location  Command
--  ----  -----      -----------  --------  -------
3   Job3  Completed  True         win2k801  dir $env:temp -recurse

When I'm ready, I'll use Receive-Job to retrieve the results which I'll save to a variable. Using –keep retains the job results:

PS Y:\> $data=Receive-Job -Name Job3 -keep
PS Y:\> $data | measure-object Length -sum

Count    : 4
Average  :
Sum      : 524301
Maximum  :
Minimum  :
Property : Length

The other approach is to open a shared interactive session as I've demonstrated in earlier lessons:

PS Y:\> Enter-PSSession -ComputerName Win2k801
[win2k801]: PS C:\Users\administrator.MYCOMPANY\Documents>

I can use a cmdlet that supports the -AsJob parameter like this:

[win2k801]: PS C:\Users\administrator.MYCOMPANY\Documents> get-wmiobject CIM_DataFile -filter "Extension='txt'" -asjob

Id  Name   State    HasMoreData  Location   Command
--  ----   -----    -----------  --------   -------
1   Job1 m Running  False        localhost  Get-WMIObject

To keep things straight, remember that I now have a background job on Win2k802 running my WMI query. This is important because when I retrieve the results, they are not transferred to my machine. They remain:

[win2k801]: PS C:\Users\administrator.MYCOMPANY\Documents> $files=Receive-job -name job1 -keep
[win2k801]: PS C:\Users\administrator.MYCOMPANY\Documents> $files.count
698

Even if I run a command like this:

[win2k801]: PS C:\Users\administrator.MYCOMPANY\Documents> $files | out-file c:\textfiles.log

The log file is created on the remote computer's C:\ drive, not mine.

You can also use Invoke-Command in an interactive remote session which supports -AsJob for even more scripting and automation power.

Note: This information is based on pre-release software and is subject to change.