Tag: powershell

The term ‘{0}’ is not recognized as the name of a cmdlet, function, script file, or operable program.

Applicable to:PowerShell Core global tool 6.2.2 and 6.2.3.
TL;DR;For the purposes of defining scope, I’m limiting the following analysis to SDKs for .NET Core versions currently in LTS and versions in between. As of this writing, that would be 2.1. 2.2, 3.0 and 3.1.

This should work well enough for most cases:

– If you can root or sudo, install whatever version of PowerShell you deem appropriate with an installer or package manager depending on your operating system;
– Else, if you have .NET Core SDK 3.1, update to PowerShell Core tool 7.0.0;
– Else update to PowerShell Core global tool 6.2.4.

For details, read on…

As written in my the last post, installing PowerShell global tool 7.0 solved the issue of initializing PowerShell extension for Visual Studio Code (ms-vscode.powershell).

But there was one thing intriguing me: While trying to initialize the extension, some writing in red was flashing in Code’s integrated terminal.

After capturing it on video and pausing it at precisely the split second the message appears it is possible to read:

-NoProfile: The term '-NoProfile' is not recognized as the name of a cmdlet, funciton, script, or operable program.
Check the spelling of the name, or if a path was included, verify that the path is correct and try again.
At line:1 char:1
+ -NoProfile -NonInteractive -EncodedCommand SQBtAHAAbwByAHQALQBNAG8AZA...
+ ~~~~~~~~~~
+ CategoryInfo          : ObjectNotFound: (-NoProfile:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException

Coincidentally, the parameters seen in the error message match those I had seen previously in the extension’s output log…

PowerShell Extension Output log

… from which I removed timestamps, log level, and truncated the log message for better display below:

Visual Studio Code v1.43.0 64-bit
 PowerShell Extension v2020.3.0
 Operating System: Linux 64-bit
 Language server starting --
     PowerShell executable: /home/alfred/.dotnet/tools/pwsh
     PowerShell args: -NoProfile -NonInteractive -Encoded...
     PowerShell Editor Services args: Import-Module '/home/...
 pwsh started.
 Waiting for session file
 Error occurred retrieving session file
 Language server startup failed.
 The language service could not be started: 
 Timed out waiting for session file to appear.

It is unfortunate that the extension’s log doesn’t show the same information that, albeit briefly, is shown in the integrated terminal – showing instead a misleading error due to some “session file”.

If we capture those parameters from the log and use them for running PowerShell directly, we’ll receive the same exact error shown in the integrated terminal.

With this we can discard ms-vscode.powershell as the source for the error and instead focus on pwsh itself.

It’s nice to see in practice the link of the failure in initializing the extension to the parsing of arguments in PowerShell Core global tool, but this doesn’t really add that much to the situation given I already had learned this is a known bug:

Older versions of the PowerShell dotnet global tool have a bug in them where arguments are not processed properly, breaking our startup invocation.

Please update your PowerShell version to 7 to enable this, or install a non-global tool PowerShell installation and configure the PowerShell extension to use it…

Although the statement pointed me in the right direction, it is imprecise and may lead some people, as was my case, to incorrect conclusions such as the only two alternatives being into install PowerShell global tool 7.0.0 or using some means of installation other than as a .NET Core tool.

Given I had very little exposure to PowerShell running on operating systems other than Windows and haven’t played at all with .NET Core tools, I took the opportunity to read through the documentation and do some testing. Here are some of my findings:

If you have root permissions or can sudo, you’re probably better off installing PowerShell using any means other than as a .NET global tool. PowerShell Core global tool can be seen as a shim over the “real thing”™, an extra layer that in versions 6.2.2 and 6.2.3 had it’s option parsing broken.

If you can’t sudo or elevate to root, you’ll have to resort to using .NET Core tools. First checkout what SDK versions are installed and confirm that PowerShell is installed as a .NET Core tool:

$ dotnet --list-sdks
 2.1.804 [/usr/share/dotnet/sdk]
 3.1.200 [/usr/share/dotnet/sdk]

$ dotnet tool list -g
 Package Id      Version      Commands
 powershell      6.2.3        pwsh

Whichever SDK versions are installed, you can always uninstall a given version, then install another version. For instance:

# dotnet tool uninstall -g powershell
 Tool 'powershell' (version '6.2.3') was successfully uninstalled.

# dotnet tool install -g --version 6.2.4 powershell
 You can invoke the tool using the following command: pwsh
 Tool 'powershell' (version '6.2.4') was successfully installed.

But upgrading can be done in a single step using dotnet tool update:

# dotnet tool update -g powershell
 Tool 'powershell' was successfully updated from version '6.2.3' to version '7.0.0'.

The command above will work as long the latest version of the .NET Core tool on the package repository is compatible with the latest .NET Core SDK version installed locally.

Otherwise, it is necessary to specify the tool version, which can only be done starting with .NET Core SDK 3.0:

# dotnet tool update -g --version 6.2.4 powershell
 Tool 'powershell' was successfully updated from version '6.2.3' to version '6.2.4'.

Automating my way out of ancillary tasks with PowerShell

After creating a handful of virtual machines for ramping up on the different Linux distros, certain configuration patterns started to emerge. Repeating those same settings over and over again in Hyper-V Manager or even PowerShell’s command line interface is kind of tedious. Good thing is scripts are a great way to automate those repetitive configuration tasks away.

In my case, the settings I kept copying over and over again were:

  • Two cores;
  • Network adapter bound to a virtual switch with external connectivity;
  • Automatic Checkpoints turned off;

And then there were other settings that although varied between distros and installation options within those distros, had to be configured each and every time:

  • Virtual machine name;
  • RAM size;
  • Hard drive size;
  • Path to installation ISO;
  • Secure Boot;

So after learning and getting comfortable with the different PowerShell cmdlets, I started prototyping a few scripts. At first, the scripts were kind of lame and buggy, but as I learned more about the features of Hyper-V and how those features are exposed through PowerShell, the scripts were improved little by little much in the spirit of Kaizen – continuous improvement.

The important thing here is realizing this as a learning tool and as such starting small and improving as you go and as new requirements make themselves known.

Important as well is knowing when to stop. The purpose of this exercise isn’t creating a production-ready script, but to create a script that will allow me to get back as soon as possible to what I settled out to do in the first place: Create virtual machines so I could learn something else.

If you are curious enough, you can find the source code for one of the early versions of the scripts as a gist over on GitHub. If you are even more curious, you can see the entire history of how the code evolved also on GitHub.

Since that early prototype, the code has evolved quite a bit from a collection of discrete scripts to the current version which is implemented as a PowerShell module and incorporates all the learnings of the last few weeks – including a best practice for creating virtual hard disks for use with Linux file systems. Good luck trying remember that one every time you create a new VM for Linux!

Certainly there are a lot of opportunities for improvement (documentation, error handling and resilience in general just to name a few), but those are left as an exercise for future self. Meanwhile, let me get back to playing with those VMs.