Added Ep8 - PowerShell Errors

Author: techthoughts2

LearnPowerShell/EP8 - PowerShell Error Handling.ps1

@@ -0,0 +1,174 @@
+#Github PowerShell error documentation:
+#https://github.com/MicrosoftDocs/PowerShell-Docs/issues/1583
+
+# Primary Pipeline aka output stream aka success pipeline
+# error pipeline
+
+#-------------------------------------------------
+#non-terminating error
+1 / 0; Write-Host 'Hello, will I run after an error?'
+
+#non-terminating errors don't stop loops
+$collection = @(
+ 'C:\Test\newcsv.csv',
+ 'c:\nope\nope.txt'
+ 'C:\Test\newcsv2.csv'
+)
+foreach ($item in $collection) {
+ Get-Item $item
+}
+#-------------------------------------------------
+#terminating errors
+
+# Without ErrorAction
+Get-Item -Path c:\nope\nope.txt; Write-Host 'Hello, will I run after an error?'
+# With ErrorAction
+Get-Item -Path c:\nope\nope.txt -ErrorAction Stop; Write-Host 'Hello, will I run after an error?'
+
+#try/catch/finally
+#https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_try_catch_finally?view=powershell-6
+
+# throw causes PowerShell to terminate
+try {
+ 1 / 0; Write-Host 'Hello, will I run after an error?'
+}
+catch {
+ throw
+}
+
+# this example will not go the catch and will run the Write-Host
+try {
+ Get-Item -Path c:\nope\nope.txt; Write-Host 'Hello, will I run after an error?'
+}
+catch {
+ Write-Host 'You are now in the catch'
+}
+
+# this example will error and go directly to the catch
+try {
+ Get-Item -Path c:\nope\nope.txt -ErrorAction Stop; Write-Host 'Hello, will I run after an error?'
+}
+catch {
+ Write-Host 'You are now in the catch'
+}
+
+
+$processNames = @(
+ 'NotAProcess',
+ 'Notepad'
+
+)
+foreach ($item in $processNames) {
+ try {
+ Get-Process -Nam $item
+ }
+ catch {
+ Write-Host $item
+ throw
+ }
+}
+
+#Write-Error simply prints the error for the user
+try {
+ 1 / 0; Write-Host 'Hello, will I run after an error?'
+}
+catch {
+ # Maybe Log Something Right here
+ Write-Error $_
+}
+
+# Finally will log results regardless of what happens
+try {
+ Get-Content -Path c:\nope\nope.txt -ErrorAction Stop
+}
+catch {
+ Write-Error $_
+}
+finally {
+ # log results to a logging file
+}
+#-------------------------------------------------
+
+#The website exists, but the page does not
+try {
+ $webResults = Invoke-WebRequest -Uri 'https://techthoughts.info/nope.htm'
+}
+catch {
+ Write-Error $_
+}
+
+#The website exists, but the page does not
+try {
+ $webResults = Invoke-WebRequest -Uri 'https://techthoughts.info/nope.htm'
+}
+catch {
+ $theError = $_
+ if ($theError.Exception -like "*404*") {
+ Write-Warning 'Web page not found. Check the address and try again.'
+ #Retry code
+ }
+ else {
+ throw
+ }
+}
+
+#The website does not exist
+try {
+ $webResults = Invoke-WebRequest -Uri 'https://techthoughtssssssss.info/'
+}
+catch {
+ $theError = $_
+ $theError.Exception
+}
+
+#The website exists, but the page does not
+try {
+ $webResults = Invoke-WebRequest -Uri 'https://techthoughts.info/nope.htm'
+}
+catch {
+ $theError = $_
+ # see all the sub-properties
+ $theError | Format-List * -Force
+}
+
+#-------------------------------------------------
+# $Error
+
+$Error
+1 / 0; $Error
+Get-Process -Name 'NotAProcess'
+$Error
+$Error.Clear()
+
+$Error[5] | Format-List * -Force
+#-------------------------------------------------
+
+#this example will help display some helpful message to the user
+#this example will only work in PowerShell 6.1+
+$uri = Read-Host 'Enter the URL'
+try {
+ $webResults = Invoke-WebRequest -Uri $uri -ErrorAction Stop
+}
+catch {
+ $statusCodeValue = $_.Exception.Response.StatusCode.value__
+ switch ($statusCodeValue) {
+ 400 {
+ Write-Warning -Message "HTTP Status Code 400 Bad Request. Check the URL and try again."
+ }
+ 401 {
+ Write-Warning -Message "HTTP Status Code 401 Unauthorized."
+ }
+ 403 {
+ Write-Warning -Message "HTTP Status Code 403 Forbidden. Server may be having issues. Check the URL and try again."
+ }
+ 404 {
+ Write-Warning -Message "HTTP Status Code 404 Not found. Check the URL and try again."
+ }
+ 500 {
+ Write-Warning -Message "HTTP Status Code 500 Internal Server Error."
+ }
+ Default {
+ throw
+ }
+ }
+}