Power Tips

Creating Large Dummy Files

2010-03-10T14:00:00Z

Sometimes, it is more efficient to use existing console tools rather than PowerShell cmdlets. For example here is a way to create a large file for load tests:

fsutil file createnew $env:temp\dummy.bin (1gb)

However, you should note that fsutil requires admin privileges.

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Running PowerShell Scripts as Scheduled Task

2010-03-09T14:00:00Z

If you have jobs that need to execute regularly, you can manage them with a PowerShell script and make it a scheduled task:

schtasks /CREATE /TN CheckHealthScript /TR "powershell.exe `
-noprofile -executionpolicy Unrestricted `
-file %public%\checkhealth.ps1" /IT /RL HIGHEST /SC DAILY

To remove the scheduled task, specify the name you assigned:

schtasks /DELETE /TN CheckHealthScript

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Launching a PowerShell Script Externally

2010-03-08T14:00:00Z

To launch a PowerShell script outside of the PowerShell console (i.e. as scheduled task or as a link), prepend the script path with this:

Powershell.exe -noprofile -executionpolicy Bypass c:\pathtoscript.ps1

As you can see, in v.2 Microsoft added an -executionPolicy parameter, which allows you to override whatever execution policy is set by default. However, your call cannot override this setting if the execution policy was defined by a group policy.

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Accessing Profile Scripts

2010-03-05T14:00:00Z

Profile scripts are executed automatically when PowerShell starts. The paths to these scripts can be found in $profile:

$profile | gm *Host* | % { $_.Name } | % {
$rv = @{}; $rv.Name = $_
$rv.Path = $profile.$_
$rv.Exists= (Test-Path $profile.$_)
New-Object PSObject -Property $rv
} | Format-Table -AutoSize

Name Path Exists
---- ---- ------
AllUsersAllHosts C:\Windows\...ps1 True
AllUsersCurrentHosts C:\Windows\...ps1 False
CurrentUserAllHosts C:\Users\...ps1 True
CurrentUserCurrentHost C:\Users\...ps1 True

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Listing Execution Policies

2010-03-04T14:00:00Z

In PowerShell v.2, there are multiple execution policies. You should use this to view and check the settings:

Get-ExecutionPolicy -List

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Closing a Program Gracefully

2010-03-03T14:00:00Z

When you use Stop-Process to kill a program, it will stop instantaneously. The user will get no chance to save unsaved documents:

Get-Process Notepad | Stop-Process

Try a more graceful way by using an internal .NET method, which then acts as if someone closed the program window. If the content has not been saved, a dialog opens and asks for a choice:

Get-Process Notepad |
Foreach-Object { $_.CloseMainWindow() | Out-Null }

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Stopping a Program Whenever You Feel Like It

2010-03-02T14:00:00Z

When you launch a program using Start-Process with -passThru, you will get back the process object representing the started program. You can then use this object later to kill the program whenever necessary.

$notepad = Start-Process notepad -passthru
Start-Sleep 2
Stop-Process -inputObject $notepad

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Use CHOICE to Prompt for Input

2010-03-01T14:00:00Z

PowerShell can run native console applications, which can be very helpful. For example, you should take a closer look at CHOICE.EXE, which will prompt you for information:

Choice /N /C:123 /M "Enter a number between 1 and 3!"
"Your choice: $LASTEXITCODE"

This will get you a simple Y/N prompt:

Choice /N /C:YN /M "Do you agree (Y/N)?"
"Your answer: $LASTEXITCODE"

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Launching Programs Maximized

2010-02-26T14:00:00Z

Start-Process has a parameter called -WindowStyle. With it, you can control the window size of the application you launch. You should use this line to launch notepad maximized:

Start-Process notepad -WindowStyle Maximized

Supported arguments are Maximized, Minimized, Normal, and Hidden. Be sure to watch out with Hidden! You should only use it for programs that do not require user interaction.

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Wait for Programs

2010-02-25T14:00:00Z

PowerShell launches Windows applications asynchronously. It only waits for the console application so you should use -wait if you want to launch a Windows application and wait for it until it finishes:

Start-Process notepad -wait

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Open Current Folder in Your Explorer

2010-02-24T14:00:00Z

If you are stuck in the console and would like to move over to the Explorer GUI, the next line opens your current folder in an Explorer window:

explorer .

Of course, this only works when the current folder is set to a folder in your file system.

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Search for Localized Keywords

2010-02-23T14:00:00Z

Finding the appropriate command for a task is important. With a little trick, PowerShell can help you. Have a look:

function ??($keywords) { Get-Help * |
? { $_.description -like "*$keywords*" } |
Select-Object Name, Synopsis }

This function called "??" searches Help content for any keyword you specify. Since Help files are localized, you can happily use keywords in your own language (the language your window uses, to be exact). For example, on German systems, you could search for "Drucker" and get back everything related to "printer":

?? drucker
?? zufall

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Filter is Faster Than Include

2010-02-22T14:00:00Z

A number of cmdlets provide two parameters that seem to work very similar: -filter and -include:

Dir $env:windir -filter *.log
Dir $env:windir -include *.log

If you have a choice, you should always pick -filter. For starters, it is much faster (4x and more) and secondly, -include only works when combined with -recurse. -filter always works.

So why is there -include at all? Because not all providers support -filter. For example, you are limited to -include when you list registry content.

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Use Online Help

2010-02-19T14:00:00Z

"To ship is to choose", so the Help files provided by PowerShell are sometimes outdated. You should use their online versions if you want to get the most accurate and up-to-date information:

Get-Help Get-Process -online

This will open a Web page with the most current version. However, it will only work on U.S. systems because of a documentation bug that you can see on localized versions:

@((get-help get-random).relatedlinks.navigationLink)[0]

As it turns out, Microsoft has added a comment "this may be in English" to the URL, so the URL breaks and you just get a bing search window on these systems.

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Get to know Parameter Sets

2010-02-18T14:00:00Z

Sometimes, you may run into issues like this once you learned more about the parameters a given cmdlet supports:

Get-Random -Minimum 1 -Maximum 50 -Count 7

Although all three parameters are valid, you will get an exception because cmdlets can separate parameters into parameter sets. But you can only use parameters of one set so you will get an exception once you try and mix parameters of different sets.

For example, the parameter sets that a cmdlet supports are listed by Get-Help:

Get-Help Get-Random

Take a look at the SYNTAX section. When you see more than one syntax, you can know that each one represents a separate parameter set. As it turns out, you cannot mix -minimum and -maximum with -count.

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