Execute any file as powershell script

Question

I encountered a challenge that I failed to resolve the way I wanted it to do.

I got a file that contains a powershell script, but that file does not have the extension assigned to powershell. The question is: How can I execute a powershell in a script file with the wrong file extension (or none)?

Invoke-Expression does not seem to work because it always executes the default action assigned to the file type. If I give that cmdlet a *.txt file the editor pops open.

I know that I can resolve that by renaming the script file or naming it properly in the first place. This is what I ended up doing.

Still I wonder if it is possible to execute a file as a script with the wrong file extension without modifying, renaming or coping the file. And if it is not working… why is that?

Answer 1

Powershell is designed such that executing or dot sourcing a file requires a .ps1 extension, and Powershell.exe will refuse to run any file that doesn't have that extension.

One way to invoke Powershell code from a non-ps1 file is to launch Powershell.exe using STDIN, and pipe your script to it. This requires a new shell, so is not very good for launching scripts from within an existing scripting environment.

Powershell.exe - < thescript.txt

Another way is to create a temporary .ps1 file and execute that. This has the advantage of using the current scripting environment, but requires a temporary file.

Copy-Item -Path '.\thescript.txt' -Dest '.\temp.ps1'
. .\temp.ps1
del .\temp.ps1

In my opinion, the file extension restriction is silly, but that's how it was designed. Apocryphally, this is for security reasons, but I can find no citation to back it up.

Answer 2

或者，您可以使用Get-Content读取文件，然后使用Invoke-Expression或Invoke-Command -ScriptBlock调用该文件。