CODEWITHSUNDEEP
powershell
Zulgrib
Zulgrib

Reputation: 638

Why a powershell command is valid in the terminal but invalid from lnk file?

For example, this command works perfectly from a PowerShell prompt :

powershell.exe -NoExit -c Set-Variable -Name "CA_HOME" -Value "$(Get-Location).Path\intermed-ca"

but fails with an error if used from an lnk file.

Set-Variable : A positional parameter cannot be found that accepts argument '\intermed-ca'.
At line:1 char:1
+ Set-Variable -Name CA_HOME -Value $(Get-Location).Path'\intermed-ca'
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Set-Variable], ParameterBindingException
    + FullyQualifiedErrorId : PositionalParameterNotFound,Microsoft.PowerShell.Commands.SetVariableCommand

Why ?

Upvotes: 0

Views: 308

Answers (1)

VertigoRay
VertigoRay

Reputation: 6273

The error you supplied is not from that particular command. Notice PowerShell is showing us the command it is erroring on.

That particular error is simply a syntax error; that is not how you concatenate strings. Running just $(Get-Location).Path'\intermed-ca' will give you an error: "Unexpected token ''\intermed-ca'' in expression or statement."

Going back to the command you posted at the top of the OP, that is proper syntax, but won't be the Path you're looking for because the logic is flawed. So, what you posted as your command will not generate an error, but will return a path that likely doesn't exist. Assuming your working directory is your user profile, you will get something like this back for $CA_HOME: C:\Users\Zulgrib.Path\intermed-ca. The reason is that you're basically doing this:

$path = (Get-Location).Path
'{0}.Path\intermed-ca' -f $path

The .Path is part of the string, not the string execution. That's why you should add parenthesis to ensure that this property is returned as part of the string execution:

powershell.exe -NoExit -c Set-Variable -Name "CA_HOME" -Value "$((Get-Location).Path)\intermed-ca"

While this is fine and will work without issues, quote translations can be tricky from the command line. So, this really isn't a perfect solution for all scenarios. For better compatibility, I would get in the habit of wrapping the whole command in double quotes and keep single quotes inside the command:

powershell.exe -NoExit -c "Set-Variable -Name 'CA_HOME' -Value ('{0}\intermed-ca' -f (Get-Location).Path)"

For the best compatibility, consider base64 encoding your command and running it with -EncodedCommand. See the very bottom of powershell.exe /? for an example. Be weary that some situations will run into issues with overly long CLI commands.

Note: '{0}\intermed-ca' -f (Get-Location).Path and '{0}\intermed-ca' -f (Get-Location) will give the same result. When PowerShell knows it's injecting a PSOobject into a string, it'll give you the string form of what you likely want.

Upvotes: 1

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