PowerShell script issue operators - powershell

Question

I am attempting to use PowerShell to detect Intel NIC drivers, prior to deploying the updated drivers. I changed my script a bit to troubleshoot, to make sure I am capturing the correct driver versions, and eventually verifying proper use of operators (which I may not be).
#Change $DeployVersion to the driver version being deployed
#Change $INTELNICMODEL to the model of Intel NIC
#=======================================================
$DeployVersion = “12.15.31.0″
$INTELNICMODEL = “82579LM”
#Get IntelNIC Driver Version from Win32_PnPSignedDriver
$CurrentlyInstalledDriverVersion = Get-WmiObject Win32_PnPSignedDriver | Where-Object {$_.deviceclass -match “NET” -and $_.devicename -like “*$INTELNICMODEL*” -and $_.driverversion} | Select driverversion
Write $CurrentlyInstalledDriverVersion.driverversion
Write $DeployVersion
If ($CurrentlyInstalledVersion.driverversion -lt $DeployVersion)
{Write “need to update driver”}
else
{Write “driver is current”}
From a computer with $CurrentlyInstalledDriverVersion = $DeployVersion
OUTPUT
PS> .\testIntelNIC.ps1
12.15.31.0
12.15.31.0
need to update driver
Clearly, this is not right, so some testing…
change -lt to -gt
OUTPUT
PS> .\testIntelNIC.ps1
12.15.31.0
12.15.31.0
driver is current
…and then try -eq
OUTPUT
PS> .\testIntelNIC.ps1
12.15.31.0
12.15.31.0
driver is current
Then from a computer where $CurrentlyInstalledDriverVersion < $DeployVersion
OUTPUT
PS> .\testIntelNIC.ps1
12.6.47.1
12.15.31.0
need to update driver
..which looks good, but…
Change -lt to -gt
OUTPUT
PS> .\testIntelNIC.ps1
12.6.47.1
12.15.31.0
driver is current
Am I using the operators incorrectly? Or the if/else?

Answer 1

String comparisons don't know anything about the inner structure of your version strings. Cast the strings to Version objects and you'll be able to do proper comparisons. Note that you need to expand the DriverVersion property for the conversion to work.
[Version]$DeployVersion = "12.15.31.0"
...
[Version]$CurrentlyInstalledDriverVersion = Get-WmiObject Win32_PnPSignedDriver |
Where-Object {
$_.deviceclass -match "NET" -and
$_.devicename -like "*$INTELNICMODEL*" -and
$_.driverversion
} | Select -Expand driverversion