Get My Things
In this issue:
I run my life from a PowerShell prompt. I have written modules, custom functions, scripts and more to make my life easier. I also love aliases and variables to speed up my workflow and save typing. The problem is that I have so many customizations, it is impossible to remember them all. I'll know I have a custom command to do something, but I can't remember what I called it, or what shortcut I created for it.
This is why PowerShell has commands like Get-Variable and Get-Command. However my challenge is to filter out the defaults. What variables are defined in my session that I created? What aliases have I defined? What commands are available to me that I created or installed? How do I get my things?
PowerShell Defaults
Conceptually, I need to compare default things with the current list of things, and filter out the defaults. I could always run:
PS C:\> $defVariable = pwsh -NoLogo -NoProfile -command "&{Get-Variable}"
PS C:\> $defVariable | Select -first 10
Name Value
---- -----
? True
^
$
args {}
ConfirmPreference High
DebugPreference SilentlyContinue
EnabledExperimentalFeatures {}
The $defVariable variable is a string. Instead of trying to parse it, I could simply return the variable names:
$defVariable = pwsh -NoLogo -NoProfile -command "&{(Get-Variable).Name}"
Then I can compare the current variable names to the default variable names:
PS C:\> Get-Variable | where {$defVariable -notContains $_.Name} | Select -first 5
Name Value
---- -----
defVariable {?, ^, $, args…}
DriveData "Name","Root","Description"…
in {@{Name=adsvw; Definition=C:\scripts\exes\ADSVW.exe; Description=…
jsonFile C:\scripts\PROSPERO-aliases.json
LASTEXITCODE 0
Another option is to use the InitialSessionState property of the current host's runspace. This property contains the default commands, variables, aliases, and more for a PowerShell session. I can use this to get the default variable names:
The object output is a little different, but nothing you can't handle.
PS C:\> $host.Runspace.InitialSessionState.Variables | Select Name,Value -first 5
Name Value
---- -----
$
^
StackTrace
PSStyle System.Management.Automation.PSStyle
OutputEncoding System.Text.UTF8Encoding+UTF8EncodingSealed
However, it appears this data isn't sufficient to define "default".
The better approach seems to be creating a new PowerShell instance.
$ps = [powershell]::Create()
I can add a command to this new instance to get the default variables:
[void]$ps.commands.AddCommand("Get-Variable")
Then invoke it.
$var = $ps.Invoke()
This should be the initial set of variables.
PS C:\> $var | select -first 10
Name Value
---- -----
? True
^
$
ConfirmPreference High
DebugPreference SilentlyContinue
EnabledExperimentalFeatures {}
Error {}
ErrorActionPreference Continue
ErrorView ConciseView
ExecutionContext System.Management.Automation.EngineIntrinsics
When you are finished with this, you should dispose of it.
$ps.Dispose()
Let's dive into how to use this to get my things.
Variables
Since I've already started on variables, let's continue. I can get an initial list of default variables from a new PowerShell instance:
$ps = [powershell]::Create()
[void]$ps.commands.AddCommand("Get-Variable")
$out = $ps.invoke()
$PSVariables = $out.name
$ps.Dispose()