PowerShell Test-Path does not work for argument-parameters - powershell

Question

During my analysis why my script isn't working I could find some solutions that solves some basic parts (also with the help of Stackoverflow), but there is still an issue for which I cannot find a solution.
When I create a temp-directory-variable $PARAM_TEMP and check this with Test-Path everything is working fine (wether the directory exists or not). But on the next part, when I use the same technique for the arguments-parameter $PARAM_DESTINATION the statement-result is wrong (I already found the hint for adding single-quotes - after this, at least the scripts runs through without errors).
When I test my test-output in console in the Windows-Explorer, it finds the directory (thus it definitely exists)
here's the content of my script BeforeInstallationScript2.ps1:
#
# BeforeInstallationScript2.ps1
#
param(
[Parameter(
Mandatory=$true,
Position=0,
HelpMessage='Path to targetDir')]
[string] $PARAM_DESTINATION
)
"1st Argument: $PARAM_DESTINATION"
# create temporary directory if not exists
$PARAM_TEMP=$env:TEMP+"\MyApp"
"temporary Directory: $PARAM_TEMP"
if(!(Test-Path -Path "$PARAM_TEMP" )){
"temp-dir does NOT exist and will be created"
New-Item -ItemType directory -Path $PARAM_TEMP
} else {
"temp-dir exist"
}
# create Timestamp-variable for saving configs
$a = Get-Date
$DATETIME= "" + $a.Year + $a.Month + $a.Day + $a.Hour + $a.Minute
"Timestamp: $DATETIME"
# if there exists already a myApp-Installation, copy config-files
"Parameter-Path=: $PARAM_DESTINATION"
"exists? = " + (Test-Path "'$PARAM_DESTINATION'" )
if((Test-Path -Path "'$PARAM_DESTINATION'" )) {
"param-path exists"
if((Test-Path -Path "'$PARAM_DESTINATION\configuration\MyApp.conf'" )) {
"copy file to $PARAM_TEMP\$DATETIME-MyApp.conf"
Copy-Item "$PARAM_DESTINATION\configuration\MyApp.conf" "$PARAM_TEMP\$DATETIME-MyApp.conf"
}
} else {
"not existing, no files to copy/save"
}
I this script in powershell get the output as follows:
PS X:\MyApp-Setup> C:\Windows\system32\WindowsPowerShell\v1.0\powershell.exe -Version 2.0 -NoProfile -NonInteractive -InputFormat None -ExecutionPolicy Bypass -File ".\BeforeInstallationScript2.ps1" "C:\Program Files (x86)\Internet Explorer"
1st Argument: C:\Program Files (x86)\Internet Explorer
temporary Directory: C:\Users\ixmid\AppData\Local\Temp\MyApp
temp-dir does NOT exist and will be created
Verzeichnis: C:\Users\USER\AppData\Local\Temp
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 16.11.2016 11:01 MyApp
Timestamp: 20161116111
Parameter-Path=: C:\Program Files (x86)\Internet Explorer
exists? = False
not existing, no files to copy/save
PS X:\MyApp-Setup>
As you can see, first Test-Path works fine, and creates the missing directory. But at the second part it doesn't work fine.
Any suggestions, why the second (and third) Test-Path-statements are working wrong?
For completion: second output of executing the script (when MyApp-directory now exists) looks as follows:
1st Argument: C:\Program Files (x86)\Internet Explorer
temporary Directory: C:\Users\USER\AppData\Local\Temp\MyApp
temp-dir exist
Timestamp: 201611161113
Parameter-Path=: C:\Program Files (x86)\Internet Explorer
exists? = False
not existing, no files to copy/save

Answer 1

You use both " quotes and ' quotes. If you want variables, $PARAM_DESTINATION in this case, to expand you need to use double quotes only. So: "$PARAM_DESTINATION".
Read up more on double and single quotes
http://windowsitpro.com/blog/single-quotes-vs-double-quotes-powershell-whats-difference