Powershell 2.0 - Running scripts for the command line call vs. from the ISE

Question

Hi,

After writing deployment scripts from within the ISE, we need our CI server to be able to run them automatically, i.e. from the command line or via a batch file.

I have notice some significant differences between the following calls:

powershell.exe -File Script.ps1
powershell.exe -Command "& '.\Script.ps1'"
powershell.exe .\Script.ps1

---

Some simple examples:

• When using -File, errors are handled in the exact same way as the ISE.
• The other two calls seem to ignore the $ErrorActionPreference variable, and do not catch Write-Error in try/catch blocks.

---

When using pSake:

• The last 2 calls work perfectly
• Using the ISE or the -File parameter will fail with the following error:

The variable '$script:context' cannot be retrieved because it has not been set

---

Could someone help me understand the implications of each syntax, and why they are behaving differently? I would ideally like to find a syntax that works all the time and behaves like the ISE.

Thanks,

Romain

Answer 1

Here is a concrete example of the behaviour I described.

MyModule.psm1

function Get-Foo
{
    Write-Error 'Failed'
}

Script.ps1

$ErrorActionPreference = 'Stop'

$currentFolder = (Split-Path $MyInvocation.MyCommand.Path)
Import-Module $currentFolder\MyModule.psm1

try
{
    Get-Foo 
    Write-Host "Success"
}
catch
{
    "Error occurred"
} 

Running Script.ps1:

• From the ISE, or with the -File parameter

  will output "Error occurred" and stop

• From the command line without the -File parameter

  will output "Failed" followed by "Success" (i.e. not caught)

Answer 2

Not an answer, just a note.

I searched for explanation of -file parameter. Most sources say only "Execute a script file.". At http://technet.microsoft.com/en-us/library/dd315276.aspx I read

Runs the specified script in the local scope ("dot-sourced"), so that the functions
and variables that the script creates are available in the current session. Enter
the script file path and any parameters.

After that I tried to call this:

powershell -command ". c:\temp\aa\script.ps1"
powershell -file c:\temp\aa\script.ps1
powershell -command "& c:\temp\aa\script.ps1"

Note that first two stop after Get-Foo, but the last one doesn't.

The problem I describe above is related to modules -- if you define Get-Foo inside script.ps1, all the 3 calls I described stop after call to Get-Foo.

Just try to define it inside the script.ps1 or dotsource the file with Get-Foo and check it. There is a chance it will work :)