Execute app install if test-path equals false - powershell

Question

I'm working on a script to test if a file exists in a target directory, and if false, execute an application installation.
The goal is to test if the file exists and if it does, abort with a log as to why. If the file does not exist, then the application installer should be executed.
I first tried creating a dummy file using New-Item to create both the directory and the dummy file.
New-Item -ItemType Directory -Force -Path "C:\temp"
New-Item -Path "C:\temp\vistaupdated.txt" -ItemType "file" -Value "Updated"
# Test if computer is updated
$file = Get-Content "C:\temp\vistaupdated.txt"
$containsWord = $file | %{$_ -match "Updated"}
if ($containsWord -contains $false) { ###start running the install stuff
However, this errors out if the file does not exist with an Object-NotFound. I then decided to switch tactics and use Test-Path:
$file = Test-Path -Path "C:\temp\vistaupdated.txt"
if ($file -eq $false) { ###start running the install stuff
In this case, I believe $file would evaluate to False and as a result execute the installation. On execution all I get is a return of the script's path:
PS C:\users\me\desktop> $filetest = Test-Path -Path "C:\temp\vistaupdated.txt"
PS C:\users\me\desktop> $filetest
False
PS C:\users\me\desktop> C:\Users\me\Desktop\vistaupdate.ps1
The above reference to the PS1 file doesn't execute. It's only what's returned if I run the script through ISE as administrator. If I do the same with the console, then the output is blank without any action taken.
# Test if computer is updated
$file = Test-Path -Path "C:\temp\vistaupdated.txt"
if ($file -eq $False) {
#package repository
$VistaInsPath = "\\apps\shared\me\vista\6.16.0"
#package installation command
$VistaInsEXE = "VistaClient.6.16.0.896"
#package installation parameters
$VistaInsParam = "/s /v/qn"
#logging
$logFile = "\\apps\shared\me\vista\6.16.0\log\vista_install.log"
#timestamp for logging
function Get-TimeStamp {
return "[{0:MM/dd/yy} {0:HH:mm:ss}]" -f (Get-Date)
}
#main function
function Vista-Install {
$errFlag = $false
try {
$cmdLine = "$VistaInsPath$VistaInsEXE"
Start-Process -FilePath $cmdLine -ArgumentList $VistaInsParam -Wait
} catch {
$(Get-TimeStamp) + "[" + $env:COMPUTERNAME +"]" + "[" + $env:USERNAME +"]" + "Error has occurred: " + $_.Exception.Message | Out-File $logFile -Append
$error.Clear()
$errFlag = $true
}
#if no error, notify success
if (-not $errFlag) {
$(Get-TimeStamp) + "[" + $env:COMPUTERNAME +"]" + "[" + $env:USERNAME +"]" + "Completed Successfully" | Out-File $logFile -Append
}
# Place dummy file to tag computer as updated
New-Item -ItemType Directory -Force -Path "C:\temp"
New-Item -Path "C:\temp\vistaupdated.txt" -ItemType "file" -Value "Updated"
}
} else {
$(Get-TimeStamp) + "[" + $env:COMPUTERNAME +"]" + "[" + $env:USERNAME +"]" + "Computer Already Updated. Aborting" | Out-File $logFile -Append
}
If Test-Path is False, then the installer should kick off in the first if statement. Instead the script spits back the path of the script itself and exits.

Answer 1

As #lit already pointed out in the comments to your question, you never invoke the function Vista-Install, so it's rather unsurprising that your code doesn't actually do anything. And you shouldn't define functions (or your $Vista* and $LogFile variables) in a nested scope anyway. The code in the else branch won't be able to find Get-TimeStamp or $LogFile with what you currently have.
Allow me to suggest some improvements:
Your logging code has a lot of redundant information. Instead of defining a function just for generating the timestamp, make a function that takes the log message as a parameter and otherwise completely encapsulates the logging.
$cmdLine = "$VistaInsPath$VistaInsEXE" will combine directory path and filename without a path separator, resulting in an incorrect path. Either put a backslash between the variables:
$cmdLine = "$VistaInsPath\$VistaInsEXE
or (better) use the Join-Path cmdlet, as #Theo suggested:
$cmdLine = Join-Path $VistaInsPath $VistaInsEXE
Put Test-Path directly in the if condition. There's no need to assign the result to a variable first.
The variable $errFlag is pointless. Just put the log statement after Start-Process. If an exception is thrown the code will go to the catch block without reaching that statement.
I assume you want the file vistaupdated.txt created only if the installation didn't throw an error, so that code should go in the try block too.
New-Item outputs an object for the item. You may want to suppress that.
The function Vista-Install doesn't make much sense either, as it would only install one specific program. Since it has very little code to begin with I would just drop it and put the code directly in the "then" branch. But if you wanted it to be a function you should name and parametrize it properly: pass program and arguments as parameters (preferably named after the parameters of Start-Process, so you can simply splat the $PSBoundParameters variable) and use a name conforming to the naming conventions:
function Install-Program {
[CmdletBinding()]
Param(
[Parameter(Mandatory=$true, Position=0)]
[string]$FilePath,
[Parameter(Mandatory=$false, Position=1)]
[string]$ArgumentList = #()
)
try {
Start-Process #PSBoundParameters
...
} catch {
...
}
}
Install-Program -FilePath (Join-Path $VistaInsPath $VistaInsEXE) -ArgumentList $VistaInsParam
Simplified code:
$VistaInsPath = '\\apps\shared\me\vista\6.16.0'
$VistaInsEXE = 'VistaClient.6.16.0.896'
$VistaInsParam = '/s', '/v', '/qn'
$logFile = '\\apps\shared\me\vista\6.16.0\log\vista_install.log'
function Write-Log {
[CmdletBinding()]
Param(
[Parameter(Mandatory=$false)]
[string]$Message = ''
)
"[{0:MM/dd/yy HH:mm:ss}]`t[{1}\{2}]`t{3}" -f (Get-Date), $env:COMPUTERNAME, $env:USERNAME, $Message |
Out-File $script:LogFile -Append
}
if (-not (Test-Path -Path 'C:\temp\vistaupdated.txt')) {
$cmdLine = Join-Path $VistaInsPath $VistaInsEXE
try {
Start-Process -FilePath $cmdLine -ArgumentList $VistaInsParam -Wait
New-Item -Path 'C:\temp' -Type Directory -Force | Out-Null
New-Item -Path 'C:\temp\vistaupdated.txt' -Type File -Value 'Updated' | Out-Null
Write-Log 'Completed successfully.'
} catch {
Write-Log ('Error has occurred: {0}' -f $_.Exception.Message)
}
} else {
Write-Log 'Computer already updated. Aborting.'
}
Arguments could be made for flipping "then" and "else" branch to avoid a negated condition:
if (Test-Path -Path 'C:\temp\vistaupdated.txt') {
Write-Log 'Computer already updated. Aborting.'
} else {
$cmdLine = ...
...
}
or exiting from the script directly if the file exists in order to avoid an else branch entirely:
if (Test-Path -Path 'C:\temp\vistaupdated.txt') {
Write-Log 'Computer already updated. Aborting.'
exit
}
$cmdLine = ...
...