Monthly Archives: October 2015

Script Sharing – Remote Desktop Prompts for Multiple Computers

Yes, I still RDP* (occasionally). I am using it less and less, but there are still times when getting inside a system’s GUI is seems necessary. I’m into this Windows PowerShell thing, if you haven’t noticed, so you can rest assured that every time I RDP, I also do my best to figure out how to get the same information using PowerShell. In fact, this often leads to new functions and tools. I just remembered this, but in the earlier days of learning PowerShell I would try and replicate everything I did in the GUI, in PowerShell. If you’re wondering how to learn PowerShell, well then, there you go.

* RDP stands for Remote Desktop Protocol. While you can’t Remote Desktop Protocol into a server, the acronym is often used as a verb: “Hey, RDP over to bigserver1 and let me know if you see the same problem.”

Anyway, let me share a function that I occasionally use. Take a look at the code, and then I’ll briefly discuss it below.

Set-Alias -Name rdp -Value Connect-TMRDP
Set-Alias -Name rdc -Value Connect-TMRDP
Function Connect-TMRDP
    [CmdletBinding()]
    Param (
        [Parameter(Mandatory=$true,Position=1,ValueFromPipeline=$true)]
        [Alias('cn')]
        [string[]]$ComputerName,

        [Parameter(Position=2)]
        [string]$DomainName
    )
    Begin {
    } #End Begin

    Process {
        If ($DomainName) {
            Foreach ($Computer in $ComputerName) {
                If ($DomainName -match '^\.') {
                    mstsc.exe /v "$Computer$DomainName"
                } Else {
                    mstsc.exe /v "$Computer.$DomainName"
                }
            }
        } Else {
            Foreach ($Computer in $ComputerName) {
                mstsc.exe /v $Computer
            }
        }
    }
}

This function allows me the ability to remote desktop into several systems at a time. While it won’t enter user names and passwords for me, it’ll present me the Windows Security logon dialog for each computer name supplied as a value to the -ComputerName parameter. That’s why I wrote it. If you’ve ever used mstsc.exe /v, and got tired of typing that over and over for each machine, now you can save time by typing something like rdp dc01,dc02,web01 and it’ll open a logon dialog for each. The rdp (and rdc) alias is created right before the function — a function I’ve named Connect-TMRDP.

Maybe this helps, may it doesn’t, but it sure speeds up the time it takes me to RDP to several servers at once. I know, I know — the simple fact that I need to RDP to several computers at once makes an even better case for PowerShell. Again, continuing to use RDP on occasion has led to some nice PowerShell tools, and I expect that this will continue.

I did want to mention one final thing about this function. It’s set up to handle the domain name being included in several different ways, if it’s included at all. Each of the examples below will work.

PS> rdp -ComputerName bigserver01
PS> rdp -ComputerName bigserver01.mydomain.com
PS> rdp -ComputerName bigserver01 -DomainName .mydomain.com
PS> rdp -ComputerName bigserver01 -DomainName mydomain.com

Cmdlet and Function Alias Best Practice

Aliases are a beautiful thing, really. Even though this may be true, we need to make sure we’re following best practice, when we opt to use them. I’m not sure what it is about me, but I get a little antsy whenever I see someone not conforming to a best practice in PowerShell. I really don’t care how you lace and tie your shoes, or make your peanut butter and jelly sandwiches, but when you use your PowerShell aliases is important to me, and it should be to you, too.

The main idea here is that cmdlet and function aliases shouldn’t exist in something that lasts longer than a one time use. That means we shouldn’t see them in help documentation (although, I believe I’ve seen some), in online articles, and in PowerShell-related forum posts. The only time you’ll see me use a cmdlet or function alias, is if you’re looking over my shoulder and watching me type commands into my console, or the ISE’s console pane. Realistically, aliases do two things: One, they help speed up getting results in a one time use scenario, as I’ve mentioned, and two, they confuse PowerShell newcomers that come across a blog where they’ve been used without consideration to best practice. Perhaps it’s my desire to help people learn PowerShell, that’s driving some of this alias indignation. I should mention, that I think it’s acceptable to include them in cases where you also explain that you’re using an alias, and indicate the full cmdlet or function name.

If you showed up here after seeing one of those blogs, or scripts, where someone littered their work with aliases, keep in mind that we have a Get-Alias cmdlet that can help you determine to which cmdlet an alias resolves — we’ll get back to that momentarily. Let’s say you found this command online:

PS> ls c:\windows | ? {$_ -like 'Win*'} | % {echo "$($_.Name)||$($_.LastWriteTime)"}

I understand this command has the potential to be written better. One such way, would be to not pipe to ? in order to filter on the file or directory name, but instead to use the ls -Filter parameter. Weird… in that last sentence, I used a couple aliases instead of their cmdlet names, and even that was confusing. Imagine having read that as a newcomer. This command, since it’s going to live on this webpage “forever,” should have been written like this (for the most part):

PS> Get-ChildItem -Path c:\windows | Where-Object {$_ -like 'Win*'} | ForEach-Object {Write-Output -InputObject "$($_.Name)||$($_.LastWriteTime)"}

It’s longer, there’s no doubt about it, but it’s much more complete and easier to comprehend, especially had you found it in a lengthy script or function.

Back to Get-Alias: If you find yourself confused by a command you found online, where someone “didn’t think of the next person,” then run though the command, or commands, and check the aliases against the Get-Alias cmdlet. Let’s do that below, for the first example command I wrote. Notice that Get-Alias will accept a comma-separated list of (alias) values.

PS> Get-Alias -Name ls,?,%,echo

CommandType     Name                                               ModuleName
-----------     ----                                               ----------
Alias           ls -> Get-ChildItem
Alias           % -> ForEach-Object
Alias           ? -> Where-Object
Alias           h -> Get-History
Alias           r -> Invoke-History
Alias           % -> ForEach-Object
Alias           echo -> Write-Output

Now, notice the results. We’ve returned aliases that we didn’t request, such as h for Get-History and r for Invoke-History. Why? A little off topic, but this is because the question mark (?), in regular expressions, or regex, stands in for a single character. The results are not only returning the alias for the question mark, but for any aliases that only have a single character. In order to only return what we want, we’ll need to escape the question mark character and put it in quotes, so that the parser is certain we have supplied the string value, of an actual question mark.

PS> Get-Alias -Name ls,'`?',%,echo

CommandType     Name                                               ModuleName
-----------     ----                                               ----------
Alias           ls -> Get-ChildItem
Alias           ? -> Where-Object
Alias           % -> ForEach-Object
Alias           echo -> Write-Output

There, we go.

As a community, we should do things so they better help the current, and future members. Use all the aliases you want, but do so where they won’t exist for someone else to stumble upon, unless, you’ve taken the time to explain that you’ve used an alias, and to which cmdlet it refers.

In closing, I want to mention the PSScriptAnalyzer module. I pulled it down and installed it in PowerShell 5.0, using the Find-Module and Install-Module cmdlets: Find-Module -Name PSScriptAnalyzer | Install-Module. I then copied my alias heavily command above, pasted it into notepad, and saved it as C:\file.ps1. Following that, I ran an Invoke-ScriptAnalyzer command. You can see the command and its results below

PS> Invoke-ScriptAnalyzer -Path C:\file.ps1 -IncludeRule PSAvoidUsingCmdletAliases

RuleName                            Severity     FileName   Line  Message
--------                            --------     --------   ----  -------
PSAvoidUsingCmdletAliases           Warning      file.ps1   1     'echo' is an alias of 'Write-Output'. Alias can
                                                                  introduce possible problems and make scripts hard to
                                                                  maintain. Please consider changing alias to its full
                                                                  content.
PSAvoidUsingCmdletAliases           Warning      file.ps1   1     '%' is an alias of 'ForEach-Object'. Alias can
                                                                  introduce possible problems and make scripts hard to
                                                                  maintain. Please consider changing alias to its full
                                                                  content.
PSAvoidUsingCmdletAliases           Warning      file.ps1   1     '?' is an alias of 'Where-Object'. Alias can
                                                                  introduce possible problems and make scripts hard to
                                                                  maintain. Please consider changing alias to its full
                                                                  content.
PSAvoidUsingCmdletAliases           Warning      file.ps1   1     'ls' is an alias of 'Get-ChildItem'. Alias can
                                                                  introduce possible problems and make scripts hard to
                                                                  maintain. Please consider changing alias to its full
                                                                  content.

The cmdlet was instructed to only return the problems it found with aliases (see the parameter used and the included value). It’s a very powerful cmdlet; not only can you find any alias-related best practice failures, but it’ll help you locate any other areas, where you can improve your code.

Thanks for your time, and… your new dedication to not use cmdlet and function aliases, that last longer than a one time use.

Update: I just saw a post from The Scripting! Guy (http://blogs.technet.com/b/heyscriptingguy/archive/2015/10/25/powertip-group-powershell-cmdlet-count-by-version.aspx) where he used a few aliases and told us what they mean. If you’re going to use them, explain them.

Run Background Commands after Every Command (Part II)

The first part of this post began on PowerShell.org. Start there, and it’ll get you to Part I: http://powershell.org/wp/2015/10/12/run-background-commands-after-every-command.

Recently I shared a small function I wrote to replace my prompt function. In addition to creating the prompt (PS: C\>) each time one command ended, it would run some background commands. In my attempt to take advantage of this function, I added code that would modify the WindowTitle, the text at the top of the console host or ISE, to indicate if there were any background jobs. Today, I’ve improved the function.

The additions I made include all of the following:
– Uses the singular word “job” when there is only one background job.
– Uses the plural word “jobs” when there is more than one background job.
– Adds an asterisk (*) when any job is actively running.
– Adds a plus sign (+) when any job has more data.

Here’s the full, updated function, and some sequential images beneath that. I’ve dumped the nested If statement for a switch statement, improving the function’s readability. Before you get into this, there’s something to consider. The indicators are only as accurate as the last time the prompt function was invoked. They won’t update without the user pressing the Enter key. That said, it’s quite convenient that you can determine if a background job is still running by pressing Enter. You don’t even have to type anything.

Function Prompt {
    If (-Not($OriginalTitle)) {
        $Global:OriginalTitle = $Host.UI.RawUI.WindowTitle
    }

    If (Get-Job) {
        $Job = Get-Job
        Switch ($Job) {
            {$Job.State -eq 'Running'} {$State = '*'}
            {$Job.HasMoreData -eq $true} {$MoreData = '+'}
            {$Job.Count -eq 1} {$Host.UI.RawUI.WindowTitle = "[$($State)Job$($MoreData)] $OriginalTitle"; break}
            {$Job.Count -gt 1} {$Host.UI.RawUI.WindowTitle = "[$($State)Jobs$($MoreData)] $OriginalTitle"}
        }
    } Else {
        $Host.UI.RawUI.WindowTitle = $OriginalTitle
    }

    "PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "
}

Run-background-commands-after-every-command-PartII-01

Run-background-commands-after-every-command-PartII-02

Run-background-commands-after-every-command-PartII-03

Run-background-commands-after-every-command-PartII-04

Update: After looking at this a few more times, I decided to move the asterisk indicator (running jobs) to the back of the word Job, or Jobs, next the plus sign indicator (has more data). I thought it looked better. The code changes I made, are seen below, and a comparison image is down there, too. Cheers!

Function Prompt {
...
            {$Job.Count -eq 1} {$Host.UI.RawUI.WindowTitle = "[Job$($State)$($MoreData)] $OriginalTitle"; break}
            {$Job.Count -gt 1} {$Host.UI.RawUI.WindowTitle = "[Jobs$($State)$($MoreData)] $OriginalTitle"}
...
}

Run-background-commands-after-every-command-PartII-05

Run Background Commands after Every Command

For a complete introduction to this post, please read the first two paragraphs at PowerShell.org: http://powershell.org/wp/2015/10/12/run-background-commands-after-every-command.

There’s a part II, now. Be sure to read that when you’re done here: http://tommymaynard.com/quick-learn-run-background-commands-after-every-command-part-ii-2015.

You know the prompt, it often looks like this: PS C:\> or this: PS>, or even this [DC05]: PS C:\Users\tommymaynard\Documents>, when you’re interactively remoting to another computer. That built-in function determines the appearance of your prompt. I’ve seen several different modifications of the prompt. You can add the the date and time to the prompt, or like the example in the about_Prompt help file, you can add ‘Hello World’ every time the prompt is displayed. Doable, yes, but helpful, probably not.

This post isn’t about changing the prompt’s appearance, but instead about doing something else inside the prompt function. What the prompt looks like is defined by a function called, prompt — you guessed it. Take a look at your current prompt, as in the example below.

PS> (Get-ChildItem -Path Function:\prompt).ScriptBlock
"PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "
# .Link
# http://go.microsoft.com/fwlink/?LinkID=225750
# .ExternalHelp System.Management.Automation.dll-help.xml

This is the standard prompt function beginning in PowerShell 3.0 up though PowerShell 5.0, the current version of PowerShell, as of this writing.

This function is invoked each time a command is run and the prompt is displayed again. What if we added additional code inside this function? It would also be run every time a new prompt was displayed. My initial idea was to add the current directory to the WindowTitle. If you don’t know what the WindowTitle is, it’s the text at the top of the console host that says “Administrator: Windows PowerShell,” or “Windows PowerShell,” when in a non-elevated host.

I tried the current directory and quickly realized it took more time to look up at the WindowTitle, from the current prompt, than to leave the default prompt alone and get this information from there. The next idea was to add the date and time to the WindowTitle. This way I would know the time the last prompt was displayed. This is practically the time the last command ended. It seemed useful… for about a minute. I finally decided on putting an indicator in the WindowTitle so that I would know if there were any background jobs or not. I seem to open and close new consoles all day long, and knowing if I was about to dump a console with an active job, whether it was still running or not, or whether it still had data, seemed useful.

Let’s walk though what I did to get this to happen. Before we do that, let’s compare the two images below. The first one shows the standard WindowTitle when there’s no job, and the [Job] indicator when there is a job. We’re going to add a few lines of PowerShell to make this happen.

run-background-commands-after-every-command01run-background-commands-after-every-command02

The first thing I did was to define a function in my profile script ($PROFILE). This function would overwrite the default prompt function, as PowerShell reads in the profile script, after it has already created the default prompt.

Function prompt {

}

Next, I enter the default, prompt text. Notice I’m not changing how the prompt is displayed.

Function Prompt {
    "PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "
}

Following this, I added the first piece of conditional logic. We test for a variable called $OriginalTitle. This variable will not exist the first time the prompt function is run, as the variable is created inside this If statement. It effectively ends up holding whatever was in WindowTitle when the console host was first opened. You’ll soon see how we reuse this value.

Before we go on, I should mention that I’ve made this a globally-scoped variable. This is because the variable needs to retain its value outside the function, and it needs to exist each time the function ends. Because of the way scope works, when we enter the function the second time and it can’t find $OriginalText, the function will go up a level and check for the existence of the variable in the parent scope, which in this case is the global scope.

Function Prompt {
    If (-Not($OriginalTitle)) {
        $Global:OriginalTitle = $Host.UI.RawUI.WindowTitle
    }

    "PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "
}

In the next part of the function, I added a check to see if the Get-Job cmdlet returns anything. If it does, there are current background jobs, and if it doesn’t, then there are no current background jobs. We’ll start with what happens when there aren’t any jobs, first. In the Else portion of this If-Else statement, we set the current WindowTitle to whatever is stored in the $OriginalTitle variable. This ensures that the WindowTitle looks just like it did when we initially started the console host and there were no background jobs.

Function Prompt {
    If (-Not($OriginalTitle)) {
        $Global:OriginalTitle = $Host.UI.RawUI.WindowTitle
    }

    If (Get-Job) {
        # Coming
    } Else {
        $Host.UI.RawUI.WindowTitle = $OriginalTitle
    }

    "PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "
}

So what happens when there are jobs? In this final portion of the function, we have an embedded If statement. If the current WindowTitle doesn’t already include the string [Job], then we add it. If it’s already there, then we leave it alone, and write the prompt.

Function Prompt {
    If (-Not($OriginalTitle)) {
        $Global:OriginalTitle = $Host.UI.RawUI.WindowTitle
    }

    If (Get-Job) {
        If ($Host.UI.RawUI.WindowTitle -NotLike '[Job]*') {
            $Host.UI.RawUI.WindowTitle = "[Job] $OriginalTitle"
        }
    } Else {
        $Host.UI.RawUI.WindowTitle = $OriginalTitle
    }

    "PS $($executionContext.SessionState.Path.CurrentLocation)$('>' * ($nestedPromptLevel + 1)) "
}

Thanks to the prompt function, we have another way to do something the moment the console is opened, and now, every time a new command is entered and a new prompt is displayed in the host. This little project has already got me wondering about some other things I may want to try with this function. I might expand what I’ve done so far, and provide indicators when there’s more than one job ([Job] vs. [Jobs]), if the jobs are still running, and perhaps if they have more data (whether it hasn’t been received yet, or was kept when it was received).

Keep in mind that this function runs after every command, successful or otherwise. Do your best not to overload the actions in the function. The default prompt comes in under a millisecond. My prompt, with the code above added, comes in at an average of 1 millisecond. If you end up doing too much in the function, you might end up waiting longer than you’re used to, making your additions to the function questionable.

Have fun, and thanks to everyone for reading this post.

Get a Locally Declared Function into a Remote Session

A part of why I write, is to have a place to store things I’m probably going to forget the moment I need them. Notice the search feature to the right. I’d be surprised to find out that someone has used it more than me.

That brings us to today’s topic: getting a locally declared function into a remote session. I wrote a recent post about getting variables into a remote sessions — you can read that here: http://tommymaynard.com/quick-learn-getting-local-variables-into-remote-sessions-2015 — and thought that getting a local function into a remote session, would make for a good followup.

First, let’s start with a function. This is a mildly complex function to use for an example, but by using it, I’ll be ensuring I can find it later, too. This function is a wrapper for the command: Dism /online /Get-Features. It takes the text produced by that command and returns the results as objects. I wrote this as part of an answer to a thread on the Microsoft Technet Forums: https://social.technet.microsoft.com/Forums/scriptcenter/en-US/972d87a9-9930-4f64-8592-5406f5fab8f4/dism-online-getfeatures-with-where-clause?forum=ITCG#01aeebe3-01b5-49cd-a8dd-1b1ce0352c8b.

Function Get-DismFeatures {
    [CmdletBinding()]
    Param ()

    Begin {
        $Results = Dism /online /Get-Features
        $Results = $Results[8..($Results.Count - 3)] | Where-Object {$_ -ne ''}

        $Feature = $Results | Select-String 'Feature'
        $State = $Results | Select-String 'State'
        $ResultsCounter = $Results.Count/2
    } # End Begin.

    Process {
        for ($i = 0; $i -lt $ResultsCounter; $i++) { 
            [pscustomobject]@{
                Feature = $Feature[$i].ToString().Split(':')[-1].Trim()
                State = $State[$i].ToString().Split(':')[-1].Trim()
            }
        }
    } # End Process.

    End {
    } # End End.
} # End Function.

Again, we could’ve use a much simpler function. Once a function is declared, we run the actions inside the function by invoking it — entering its name into the console. To run this locally, we’d just enter Get-DismFeatures, press Enter, and it would produce the results below. I’ve greatly shortened the results to save space.

PS C:\> Get-DismFeatures

Feature                                                     State
-------                                                     -----
Microsoft-Hyper-V-All                                       Enabled
Microsoft-Hyper-V-Tools-All                                 Enabled
Microsoft-Hyper-V                                           Enabled
Microsoft-Hyper-V-Management-Clients                        Enabled
Microsoft-Hyper-V-Management-PowerShell                     Enabled
Printing-Foundation-Features                                Enabled
Printing-Foundation-LPRPortMonitor                          Disabled
Printing-Foundation-LPDPrintService                         Disabled
...

To run this on a remote computer, or computers, we would need to ensure PS Remoting is available and working. You can test this with your own computer, or with a remote computer. Yes, you can use your local computer to determine if PS Remoting is working from, and into, your computer. Here’s three different examples of using my own computer, and one example of using a remote one.

PS> Invoke-Command -Computer localhost -ScriptBlock {$env:COMPUTERNAME}
TOMMYSCPU
PS> Invoke-Command -Computer . -ScriptBlock {$env:COMPUTERNAME}
TOMMYSCPU
PS> Invoke-Command -ScriptBlock {$env:COMPUTERNAME}
TOMMYSCPU
PS> Invoke-Command -Computer DC05 -ScriptBlock {$env:COMPUTERNAME}
DC05

Okay, so on to taking the function to a remote computer. Here’s how we do that (also with shorten results). Notice the placement of the dollar sign ($). This is different that we saw when taking locally declared variables to the remote session.

PS> Invoke-Command -ComputerName DC05 -ScriptBlock ${function:Get-DismFeatures}

Feature        : NetFx4ServerFeatures
State          : Enabled
PSComputerName : DC05
RunspaceId     : 72dc5b41-31b8-22b1-b5b1-29eae648123a

Feature        : NetFx4
State          : Enabled
PSComputerName : DC05
RunspaceId     : 72dc5b41-31b8-22b1-b5b1-29eae648123a
...

And, that’s it.

If you’re like me, you’re sitting back now and wondering, “Why not include the ability to run the function against remote computers, inside the function?” That’s an option, and often employed to make a function useful on both local and remote systems. Here’s the thing: You may not always write the tools you use, so having a way to use one that was written without a way to run it remotely, might be helpful one day.