Sometimes you have to create a custom script that requires external files, e.g. binary dll files or executables.

One of the ways you can make sure the script is executed succesfully is by creating a component that first copies the necessary files to the correct locations using the FileCopy action item, but today I am going to show you how to embed a file in a script using base64 encoding. 

Encoding the file

The file we want to embed is called AM.dll and is located on my development machine in c:\AM\AM.dll.

Embedding a .dll file

To encode the file to base64 we give in the following commands in powershell prompt:

$Content = Get-Content -Path C:\AM\AM.dll -Encoding Byte
$Base64 = [System.Convert]::ToBase64String($Content)
$Base64 | Out-File c:\AM\encoded.txt

The result should be a file called encoded.txt in c:\AM.

Encoded text file

Open the encoded.txt file and you will see a base64 encoded string representation of the dll file.

Base64 encoded string

Embedding the file

To embed the file, simply create a new variable in your script which contains the base64 string.

$Base64 = "TVqQAAMAAAAEAAAA//8AALgAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
..........+DDEAsAA+DDkAsAA+DEEAsAA+DEkAsAA+DFEAsABDDFkAsAA+DGEAsAA+DGkAsAA+DHEAsABIDIEAsABODIkAsAAOAJEA6gYSAJkAAAdTDAkA"

NOTE: The example above has been cropped for readiblity of the blogpost, this should be a rather long string.

Decoding the file

After we have embedded the base64 string representation of the file we need to decode it to a dll file before we can use it.

$Content = [System.Convert]::FromBase64String($Base64)
Set-Content -Path $env:temp\AM.dll -Value $Content -Encoding Byte

Now we can use the $env:temp\AM.dll file in the rest of our script, for housekeeping reasons, remove the dll file at the end of the script.

Remove-Item $env:temp\AM.dll

The entire script would look like

$Base64 = "TVqQAAMAAAAEAAAA//8AALgAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
..........+DDEAsAA+DDkAsAA+DEEAsAA+DEkAsAA+DFEAsABDDFkAsAA+DGEAsAA+DGkAsAA+DHEAsABIDIEAsABODIkAsAAOAJEA6gYSAJkAAAdTDAkA"
$Content = [System.Convert]::FromBase64String($Base64)
Set-Content -Path $env:temp\AM.dll -Value $Content -Encoding Byte
#Do your things
Remove-Item $env:temp\AM.dll

There you go, a way to embed files in a powershell script, ensuring that the external files the script requires will always be there (with the right version, might I add).

Happy encoding and embedding.

Ps. Also, make sure to read my colleague Mark's blog about cleaning up esxtop log files using PowerShell.

 

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