Powershell - How to complete/close a zip file in powershell - powershell

Question

I want to create a zip file in powershell, add items to the zip file, then get the compressed content of that zip file as bytes immediately after the zip file is created, in the same scipt. The problem is that it does not seem that the zip application has written its contents to the file system. How does one close/flush the zip application so that the next powershell statement can gain access to the newly created zip file?
Example:
new-item -type File test.zip -force
$zip = ( get-item test.zip ).fullname
$app = new-object -com shell.application
$folder = $app.namespace( $zip )
$item = new-item file.txt -itemtype file -value "Mooo" -force
$folder.copyhere( $item.fullname )
dir test.zip # <---- Empty test.zip file
Get-Content -Encoding byte $zip | echo # <-- nothing echoed
The "dir test.zip" shows a zip file with no contents, thus the Get-Content returns nothing.
Please note that this seems to be a problem with the asynchronous behavior of the copyhere action. If I sleep after the copyhere line, the zip file will become populated. However, I do not know how long one must sleep, nor do I want to delay the processing.
Much Thanks in advance!

Answer 1

You might want to reconsider using a third party library. However, if you must use copyhere, try this:
new-item -type File test.zip -force
$zip = ( get-item test.zip ).fullname
$app = new-object -com shell.application
$folder = $app.namespace( $zip )
$item = new-item file.txt -itemtype file -value "Mooo" -force
$folder.copyhere( $item.fullname)
while($folder.Items().Item($item.Name) -Eq $null)
{
start-sleep -seconds 0.01
write-host "." -nonewline
}
dir test.zip # <---- Empty test.zip file
Get-Content -Encoding byte $zip

Answer 2

I also had this problem, all that you need is to wait until zipping operation is not completed. So, i come up with this solution, you should place this code after executing "$folder.copyhere" or "Copy-ToZip" powerpack cmdlet.
$isCompleted = $false
$guid = [Guid]::NewGuid().ToString()
$tmpFileName = $zipFileName + $guid
# The main idea is to try to rename target ZIP file. If it success then archiving operation is complete.
while(!$isCompleted)
{
start-sleep -seconds 1
Rename-Item $zipFileName $tmpFileName -ea 0 #Try to rename with suppressing errors
if (Test-Path $tmpFileName)
{
Rename-Item $tmpFileName $zipFileName #Rename it back
$isCompleted = $true
}
}

Answer 3

This method to zip files is not appropriate for automated scripts. This has limitations in Windows 2003 and Windows xp server for 3 gigs. Also, it does not give proper errors.

Answer 4

Create the file in a closure, so that the variable goes out of scope and powershell closes the file... if you'd made that part into a subroutine then it would have closed naturally when you returned.
new-item -type File test.zip -force
{
$zip = ( get-item test.zip ).fullname
$app = new-object -com shell.application
$folder = $app.namespace( $zip )
$item = new-item file.txt -itemtype file -value "Mooo" -force
$folder.copyhere( $item.fullname )
}
dir test.zip # <---- Empty test.zip file
Get-Content -Encoding byte $zip

Answer 5

try creating the zip empty file like this:
$zipfilename = "myzip.zip"
set-content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
Then the rest of your code.
this code in my box works:
$zipfilename = "a.zip"
set-content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
$app = new-object -com shell.application
$zip = ( get-item a.zip ).fullname
$folder = $app.namespace( $zip )
$item = new-item file.txt -itemtype file -value "Mooo" -force
$folder.copyhere( $item.fullname )
to get the content of a zip use this:
$zipfilename = "myzip.zip"
$shellApplication = new-object -com shell.application
$zipPackage = $shellApplication.NameSpace($zipfilename)
$zipPackage.Items() | Select Path