Can Windows' built-in ZIP compression be scripted? - windows

Question

Is the ZIP compression that is built into Windows XP/Vista/2003/2008 able to be scripted at all? What executable would I have to call from a BAT/CMD file? or is it possible to do it with VBScript?
I realize that this is possible using WinZip, 7-Zip and other external applications, but I'm looking for something that requires no external applications to be installed.

Answer 1

There are VBA methods to zip and unzip using the windows built in compression as well, which should give some insight as to how the system operates. You may be able to build these methods into a scripting language of your choice.
The basic principle is that within windows you can treat a zip file as a directory, and copy into and out of it. So to create a new zip file, you simply make a file with the extension .zip that has the right header for an empty zip file. Then you close it, and tell windows you want to copy files into it as though it were another directory.
Unzipping is easier - just treat it as a directory.
In case the web pages are lost again, here are a few of the relevant code snippets:
ZIP
Sub NewZip(sPath)
'Create empty Zip File
'Changed by keepITcool Dec-12-2005
If Len(Dir(sPath)) > 0 Then Kill sPath
Open sPath For Output As #1
Print #1, Chr$(80) & Chr$(75) & Chr$(5) & Chr$(6) & String(18, 0)
Close #1
End Sub
Function bIsBookOpen(ByRef szBookName As String) As Boolean
' Rob Bovey
On Error Resume Next
bIsBookOpen = Not (Application.Workbooks(szBookName) Is Nothing)
End Function
Function Split97(sStr As Variant, sdelim As String) As Variant
'Tom Ogilvy
Split97 = Evaluate("{""" & _
Application.Substitute(sStr, sdelim, """,""") & """}")
End Function
Sub Zip_File_Or_Files()
Dim strDate As String, DefPath As String, sFName As String
Dim oApp As Object, iCtr As Long, I As Integer
Dim FName, vArr, FileNameZip
DefPath = Application.DefaultFilePath
If Right(DefPath, 1) <> "\" Then
DefPath = DefPath & "\"
End If
strDate = Format(Now, " dd-mmm-yy h-mm-ss")
FileNameZip = DefPath & "MyFilesZip " & strDate & ".zip"
'Browse to the file(s), use the Ctrl key to select more files
FName = Application.GetOpenFilename(filefilter:="Excel Files (*.xl*), *.xl*", _
MultiSelect:=True, Title:="Select the files you want to zip")
If IsArray(FName) = False Then
'do nothing
Else
'Create empty Zip File
NewZip (FileNameZip)
Set oApp = CreateObject("Shell.Application")
I = 0
For iCtr = LBound(FName) To UBound(FName)
vArr = Split97(FName(iCtr), "\")
sFName = vArr(UBound(vArr))
If bIsBookOpen(sFName) Then
MsgBox "You can't zip a file that is open!" & vbLf & _
"Please close it and try again: " & FName(iCtr)
Else
'Copy the file to the compressed folder
I = I + 1
oApp.Namespace(FileNameZip).CopyHere FName(iCtr)
'Keep script waiting until Compressing is done
On Error Resume Next
Do Until oApp.Namespace(FileNameZip).items.Count = I
Application.Wait (Now + TimeValue("0:00:01"))
Loop
On Error GoTo 0
End If
Next iCtr
MsgBox "You find the zipfile here: " & FileNameZip
End If
End Sub
UNZIP
Sub Unzip1()
Dim FSO As Object
Dim oApp As Object
Dim Fname As Variant
Dim FileNameFolder As Variant
Dim DefPath As String
Dim strDate As String
Fname = Application.GetOpenFilename(filefilter:="Zip Files (*.zip), *.zip", _
MultiSelect:=False)
If Fname = False Then
'Do nothing
Else
'Root folder for the new folder.
'You can also use DefPath = "C:\Users\Ron\test\"
DefPath = Application.DefaultFilePath
If Right(DefPath, 1) <> "\" Then
DefPath = DefPath & "\"
End If
'Create the folder name
strDate = Format(Now, " dd-mm-yy h-mm-ss")
FileNameFolder = DefPath & "MyUnzipFolder " & strDate & "\"
'Make the normal folder in DefPath
MkDir FileNameFolder
'Extract the files into the newly created folder
Set oApp = CreateObject("Shell.Application")
oApp.Namespace(FileNameFolder).CopyHere oApp.Namespace(Fname).items
'If you want to extract only one file you can use this:
'oApp.Namespace(FileNameFolder).CopyHere _
'oApp.Namespace(Fname).items.Item("test.txt")
MsgBox "You find the files here: " & FileNameFolder
On Error Resume Next
Set FSO = CreateObject("scripting.filesystemobject")
FSO.deletefolder Environ("Temp") & "\Temporary Directory*", True
End If
End Sub

Answer 2

Yes, this can be scripted with VBScript. For example the following code can create a zip from a directory:
Dim fso, winShell, MyTarget, MySource, file
Set fso = CreateObject("Scripting.FileSystemObject")
Set winShell = createObject("shell.application")
MyTarget = Wscript.Arguments.Item(0)
MySource = Wscript.Arguments.Item(1)
Wscript.Echo "Adding " & MySource & " to " & MyTarget
'create a new clean zip archive
Set file = fso.CreateTextFile(MyTarget, True)
file.write("PK" & chr(5) & chr(6) & string(18,chr(0)))
file.close
winShell.NameSpace(MyTarget).CopyHere winShell.NameSpace(MySource).Items
do until winShell.namespace(MyTarget).items.count = winShell.namespace(MySource).items.count
wscript.sleep 1000
loop
Set winShell = Nothing
Set fso = Nothing
You may also find http://www.naterice.com/blog/template_permalink.asp?id=64 helpful as it includes a full Unzip/Zip implementation in VBScript.
If you do a size check every 500 ms rather than a item count it works better for large files. Win 7 writes the file instantly although it's not finished compressing:
set fso=createobject("scripting.filesystemobject")
Set h=fso.getFile(DestZip)
do
wscript.sleep 500
max = h.size
loop while h.size > max
Works great for huge amounts of log files.

Answer 3

Just for clarity: GZip is not an MS-only algorithm as suggested by Guy Starbuck in his comment from August.
The GZipStream in System.IO.Compression uses the Deflate algorithm, just the same as the zlib library, and many other zip tools. That class is fully interoperable with unix utilities like gzip.
The GZipStream class is not scriptable from the commandline or VBScript, to produce ZIP files, so it alone would not be an answer the original poster's request.
The free DotNetZip library does read and produce zip files, and can be scripted from VBScript or Powershell. It also includes command-line tools to produce and read/extract zip files.
Here's some code for VBScript:
dim filename
filename = "C:\temp\ZipFile-created-from-VBScript.zip"
WScript.echo("Instantiating a ZipFile object...")
dim zip
set zip = CreateObject("Ionic.Zip.ZipFile")
WScript.echo("using AES256 encryption...")
zip.Encryption = 3
WScript.echo("setting the password...")
zip.Password = "Very.Secret.Password!"
WScript.echo("adding a selection of files...")
zip.AddSelectedFiles("*.js")
zip.AddSelectedFiles("*.vbs")
WScript.echo("setting the save name...")
zip.Name = filename
WScript.echo("Saving...")
zip.Save()
WScript.echo("Disposing...")
zip.Dispose()
WScript.echo("Done.")
Here's some code for Powershell:
[System.Reflection.Assembly]::LoadFrom("c:\\dinoch\\bin\\Ionic.Zip.dll");
$directoryToZip = "c:\\temp";
$zipfile = new-object Ionic.Zip.ZipFile;
$e= $zipfile.AddEntry("Readme.txt", "This is a zipfile created from within powershell.")
$e= $zipfile.AddDirectory($directoryToZip, "home")
$zipfile.Save("ZipFiles.ps1.out.zip");
In a .bat or .cmd file, you can use the zipit.exe or unzip.exe tools. Eg:
zipit NewZip.zip -s "This is string content for an entry" Readme.txt src

Answer 4

There are both zip and unzip executables (as well as a boat load of other useful applications) in the UnxUtils package available on SourceForge (http://sourceforge.net/projects/unxutils). Copy them to a location in your PATH, such as 'c:\windows', and you will be able to include them in your scripts.
This is not the perfect solution (or the one you asked for) but a decent work-a-round.

Answer 5

to create a compressed archive you can use the utility MAKECAB.EXE

Answer 6

Here'a my attempt to summarize built-in capabilities windows for compression and uncompression - How can I compress (/ zip ) and uncompress (/ unzip ) files and folders with batch file without using any external tools?
with a few given solutions that should work on almost every windows machine.
As regards to the shell.application and WSH I preferred the jscript
as it allows a hybrid batch/jscript file (with .bat extension) that not require temp files.I've put unzip and zip capabilities in one file plus a few more features.