PowerShell throws “Cannot convert value to type System.String” when an advanced function’s [string] parameter receives an array instead of one value. Call it once per item, or join the items into one string: In this tutorial, I’ll show you how to reproduce cannot convert value to type system.string, find the hidden array behind it, and … Read more
PowerShell has two main error variables. $Error is an automatic list of every recent error in the session, newest first, and -ErrorVariable saves one command’s errors into a variable you name: In this tutorial, I’ll walk through the PowerShell error variables you’ll actually use: $Error, -ErrorVariable, $? and $LASTEXITCODE. You’ll also see where PowerShell 7 … Read more
To list printers using PowerShell, run Get-Printer. It returns every printer and printer connection installed on the computer, and you don’t need admin rights. Pipe it to Format-Table to pick the columns: In this post I’ll show you how to list printers using PowerShell with Get-Printer and Win32_Printer, read their status, find network printers, and … Read more
To find the WWN number in Windows with PowerShell, run Get-InitiatorPort and filter for Fibre Channel ports. NodeAddress is the WWNN and PortAddress is the WWPN: Storage admins ask for the WWPN when they zone a switch or map LUNs to a server. Below I format the numbers the way SAN tools expect them, query … Read more
You want a script to show friendly status messages, maybe in green or red, without those messages leaking into the data it returns. That’s exactly the job Write-Host was built for. Quick answer: PowerShell Write-Host prints text straight to the console (the host), with optional -ForegroundColor, -BackgroundColor, -NoNewline and -Separator. It doesn’t send objects down … Read more
Get-ChildItem is the PowerShell cmdlet that lists what’s inside a location: the files and folders in a directory, the keys in a registry hive or the certificates in a store. Point it at a folder and you get the contents back as objects: I reach for it in almost every file script I write. Below … Read more
PowerShell Compare-Object takes two sets of objects and tells you which items exist on only one side. Give it a reference set and a difference set, and it returns the mismatches with an arrow showing where each one came from: I use it constantly for audits: two server lists, two folders, last month’s staff export … Read more
To read log files with PowerShell, use Get-Content for the lines and Select-String to find the ones that matter: The first line shows the newest 20 entries, and the second lists every error with its file name and line number. I tested each step below on sample Contoso logs in PowerShell 7 and Windows PowerShell … Read more
To find all files with a specific extension using PowerShell, run Get-ChildItem with -Filter, -Recurse and -File: That walks C:\Data and every subfolder and returns only .pdf files. Below, I test each variation on a small sample folder in PowerShell 7 and Windows PowerShell 5.1, including one 5.1 quirk that quietly adds the wrong files. … Read more
“‘Install-Module’ is not recognized as an internal or external command” means you typed the command into Command Prompt, not PowerShell. Open PowerShell and run it there, or call it from cmd like this: If PowerShell itself says the term isn’t recognized, the cause is different. I reproduced each one below in PowerShell 7 and Windows … Read more