Making your (Powershell) job work for you

Jobs are a in many ways the key to Powershell multithreading. Having jobs running in the background not only allows you to keep working in your console while your script is silently churning away in the background, but it also lets you run multiple commands or scripts simultaneously executed from console.

When to use jobs

Whenever you’d like to run a command or a scriptblock without locking up your console, or when you’d like to run multiple commands simultaneously. Jobs are “fire and forget” tasks that you don’t review until they’ve completed or failed.

When not to use jobs

When running basic administration tasks where you’re reviewing output or the result of command continuously, or when working with result sets in variables where you’d like to keep reviewing the current value of the variable.

Ways to use jobs

There are two ways of using jobs in Powershell. First of all, many cmdlets have the parameter “-AsJob” to allow them run in the background directly. Alternatively you can use the cmdlet Start-Job to initiate a job with any cmdlet of combination of commands.

-AsJob

Some cmdlets that has the -AsJob parameter are:
Get-WmiObject
Invoke-Command
Invoke-WmiMethod
Remove-WmiObject
Restart-Computer
Set-WmiInstance
Stop-Computer
Test-Connection

If you like to find a more complete list, use the following command.

NB. Keep in mind that you need to load the modules your looking for commands in, in advance. Module autoloading doesn’t work when looking for parameters (Tested with Powershell 5.0 in Windows 10 Technical Preview)

Cmdlets

There are 4 cmdlets that are key to using Powershell jobs:

Start-Job

Starts a background job to execute one or more Powershell commands.

 Get-Job

Collects and lists the running and completed jobs currently in memory

 Receive-Job

Presents the result of a job to screen, or otherwise lets you collect or manipulate the result

 Remove-Job

Removes one or more jobs from memory

 Other useful cmdlets:

Suspend-Job: Pauses a job.
Resume-Job: Resumes a paused job.
Stop-Job: Stops a job.
Wait-Job: Suspends the command prompt until a job is finished, preventing you from making the input.

RSAT for Windows 10 Technical Preview

Those who have tried have failed. Installing Remote Server Admin Tools (RSAT) for Windows 8 on Windows 10 Technical Preview won’t work. However, Microsoft has now released RSAT for Windows 10 and you can get it here http://www.microsoft.com/en-us/download/details.aspx?id=44280

Measuring directory sizes

I wanted to take out a very simple report on the largest sub folders in terms of size, for a profile area on a client site. We have tools to do this, but scripting it was in this case a very quick and dirty way to get the job done.

This script is reusable on all folders. It will enumerate the size of the content of all sub folders on the folder on which you run it, measured in megabytes.

 

SQL non-system database backup using Powershell

Traditionally most People have been automating database backups in Microsoft SQL server using TransactSQL, and then using osql to execute the code through Windows Task Scheduler. With the advent of MSSQL 2012, using Powershell to automate SQL related taks has suddenly become a lot easier.

This script selects only user databases though, ignoring system databases and leaves you with only what should be important to you.

As a part of a migration at a client, I was given the task of creating an efficient backup strategy with minimal effort. Using TransactSQL would definitely solve the task, but for future reference, I always try to use Powershell when applicable.

So how does the script work? Well, first we collect paths and dates necessary to perform the backup and name the file for the backup set. The backup file is tagged with the week number and the script is meant to create a backup set every week.

Next we create two Functions. The first creates a full backup, the second will add incremental backups to the backup set file created by the first function. I.e., the second will be pointless if the first has not run.

Last, we choose which of the previously created functions to run. This is also where you choose when to create the full backup set. Simply change the weekday in the script. Mind your spelling though, it needs to be accurate.

So this is all nice and dandy. It’ll keep churning out backup sets every week, filling up your storage SAN, local hard drive, cloud storage or what ever storage you choose to add the backup set to. So what can we do to clean it up?

Well, keep in mind that all backup sets are tagged with the week number in the file name. This makes it easy to choose which backup set to restore, but it also makes it easy to choose which to delete. Simply {$CurrentWeek – 2}. Here a script that does exactly that:

Please feel free to leave your comments if you have and questions regarding this solution, and I’d love to hear from anyone who uses this fully or partially 🙂

Powershell Port Scanner

Would you like to know what ports are open on a host? With the introduction of Powershell 4.0 there’s a new cmdlet called Test-Netconnection which in it’s simples form basically is ping. It does, however, have some more advanced features, like scanning towards ports on a host.

Here’s a quick and dirty script to scan a single host for single port, or a sequential range of ports.

I have to admit that I miss the -Source switch in “Test-Connection” that allows you to choose where the connection request should originate, but perhaps we’ll see that in Powershell/WMF 5.0?

Techtip: One-liner to get free space

Say you’d like to copy an exuberant amount of data from one server to another and you’re unsure if the target disk has sufficient space. Perhaps you’d simply like to know how much space you’ve got.  There are several way to check this, but here’s one more, and in my opinion the fastest:

Run this one-liner from any computer, and as long as you run it a user context where you have user rights on the server, you will get the amount of free space in GB.

You can also use this a basis for a script listing out renaming space on several computers or several disks on a single server, but that might be the subject for another article!

Working around number ranges limited to 32 bit integers

I head a real brain teaser when working a script earlier today. Basically I was modifying a script which lists out unused phone numbers in a range. It turns out German phone numbers (and any number greater than 2147483647) are incompatible with number ranges. Here’s why, and how to solve it.

When using number ranges, you are limited to signed 32 bit integers (-2147483646 to +2147483647). This is rarely an issue, but when working with untypical numbers, like unformatted phone numbers or the byte value of very large files, it can pose a problem.

This is an example of a range that will work:

This however, won’t work:

The high number is above the max value for a signed 32 bit integer.

Solving required a bit of a hack. To work around this limitation, use a While loop to create an array with the number series you’d like to feed into to your variable. Below is an example:

$Counter is initially set to be the starting number of your range. It will be the control parameter that the While loop uses to check if it’s done working.
$NumberStart is the starting (low) number in you range.
$NumberEnd is the end (high) number in you range
$Array is your range (or it’s equivalent). It gets fed each value from $NumberStart to $NumberEnd. This array will hold 64 bit integers.

 

Solving ReFS integrity bit issues when working with Hyper-V

I was working with Hyper-V and I got the following error:

Export failed for virtual machine ‘webtest01’ (16CED29C-F6B2-4D86-91D1-DDBD635D24C2) with error ‘The requested operation could not be completed due to a virtual disk system limitation. On NTFS, virtual hard disk files must be uncompressed and unencrypted. On ReFS, virtual hard disk files must not have the integrity bit set.’ (0xC03A001A).

The volume I’m working on was an ReFS volume on a Storage Pool located on my test environment. I tried troubleshooting this issue, but there is hardly any good help online. Googling the issue gav me a few obscure Technet references and some rather incomplete blog posts, so this article is a concatenation of the information I found.

List out the files in your “Virtual Hard Disks” folder using this command:

Change the integrity bit on files using this command:

Or, use this one-liner:

I hope this helps shed some light on this issue.

Get rich quick, autogenerate lotto numbers

You can retire soon. With my fantastic “Generate lotto numbers automagically” script, you no longer need to let imagination keep you from playing the lottery!

This script will auto generate a number of unique lottery numbers. You can configure the amount of numbers, and the range to generate the numbers from by changing he value of variable in the script.

NB. Should you win big using numbers from script, my bank account is always open for donations 😉

 

 

 

Using Powershell to identify Child Processes

I got a challenge yesterday on how to identify child processes, and googling it led to the conclusion that this is either not a common issue or no one knows the answer.

My issue was this: if a child process locks up or needs to be killed, how do we identify the process using powershell. The thing about finding child processes is that you need to know who their parents are. In fact, you need to use the parent process id (PID) to identify the child.

How does it work?

First choose how to identify the parent process in Powershell. You can usually use ProcessName, Description, Path etc. Then you need to find any process which has the ParentProcessId of it’s parent (obviously)!

Here’s my solution:

$procid = (Get-WmiObject win32_process | where {$_.ProcessName -eq ‘Powershell.exe’} | select processid)
Get-WmiObject win32_process | where {$_.ParentProcessId -eq $id}

This only identifies the child process, what you’d like to do with it afterwards is your call. Nonetheless, this could help you automate some of the tasks you’ve been using Process Explorer to solve until now.