Powershell script uses the user's home directory as current working dir when using .NET ZipFile.CreateFromDirectory. How to fix?

Question

Here's my script (createdistro.ps1)

Add-Type -assembly "system.io.compression.filesystem"

$source = "bin\Debug\"
$destination = "gwtester_signed.zip"

If(Test-path $destination) {Remove-item $destination}
[io.compression.zipfile]::CreateFromDirectory($source, $destination)

Notice the error message I get from running the script:

PS C:\dev\DEV7\Test\gwtester> .\createdistro.ps1
Exception calling "CreateFromDirectory" with "2" argument(s): "The file 'C:\Users\bbren\gwtester_signed.zip' already
exists."
At C:\dev\DEV7\Test\gwtester\createdistro.ps1:7 char:1
+ [io.compression.zipfile]::CreateFromDirectory($source, $destination)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : IOException

As you can see, the script attempts to write to C:\Users\bbren\gwtester_signed.zip, but the current working directory is C:\dev\etc\.

The documentation for ZipFile.CreateFromDirectory states that "A relative path is interpreted as relative to the current working directory."

What is wrong?

Current PowerShell location and current working directory is two different things. — user4003407, Mar 09 '16 at 13:03

score 2 · Answer 1 · answered Mar 09 '16 at 13:36

2

I don't recommend $PSScriptRoot.

Try this:

$destination = Join-Path (Get-Location) 'gwtester_signed.zip'

But depending on your psversion, how about Expand-Archive?

answered Mar 09 '16 at 13:36

Max

77
5

OK. How would you do it if the destination file path was passed from the command line? To support both relative and absolute paths? – codeape Mar 09 '16 at 13:37
I ended up using Compress-Archive. But I would still like to understand how Powershell handles absolute and relative paths. I'm baffled as to why CreateFromDirectory uses the user's home directory, instead of the current working dir. – codeape Mar 09 '16 at 13:38
Why not `$PSScriptRoot`? I understand it as a variable containing the directory of the running script. – G42 Mar 09 '16 at 13:43
@gmsoulman your understanding is correct. I assume the user may not always want zip files to land in the script's folder. – Max Mar 09 '16 at 13:51
2

@codeape afaik providing a relative path to .net objects in ps will be resolved relative to $env:userprofile. to support relative paths, you can use $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath($Path). that will convert itself to a absolute path if required,. – Max Mar 09 '16 at 14:00

score 1 · Answer 2 · answered Mar 09 '16 at 13:17

1

Change $destination = "gwtester_signed.zip" to $destination = "$PSScriptRoot\gwtester_signed.zip"

answered Mar 09 '16 at 13:17

G42

9,791
2
19
34

score 0 · Answer 3 · edited May 23 '17 at 10:28

I've actually added this to my prompt function to keep the .NET and Powershell view of what the current working directory is in sync. There's probably a load of reasons this is a BadIdea™ - but it works for me :

[System.Environment]::CurrentDirectory = $PWD

Of course, you could just call that before you want to run a .NET method that cares about it too.

Edit: Ah yes, this question points out why this might end up being a bad idea : Why don't .NET objects in PowerShell use the current directory?

Edit2: and in light of the above, I've now changed my prompt function to do this :

if($PWD.Provider.Name -eq 'Filesystem'){
    [System.Environment]::CurrentDirectory = $PWD
}

So that the attempt to update the .NET view of current directory only happens when the current Powershell provider is the Filesystem one.

Powershell script uses the user's home directory as current working dir when using .NET ZipFile.CreateFromDirectory. How to fix?

3 Answers3