Source/Public/Demo-Construct.ps1
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# Filename: Demo-Construct.ps1 # Author: Frits van Drie (3-Link.nl) # Date: 2022-04-06 #region: If, ElseIf, Else <# If (Condition1) {Action1} ElseIf (Condition2) {Action2} ElseIf (Condition3) {Action3} Else {Action4} #> $one = 1 $two = 2 If ($one -eq 0 -or $two -eq 0) {Write-Host "$one or $two is Zero"} ElseIf ($one -gt $two) {Write-Host "$One > $Two"} ElseIf ($one -lt $two) {Write-Host "$One < $Two"} Else {Write-Host "$One = $Two"} Suspend-Service workstation Get-Service 'l*' | ForEach-Object { if ($_.status -eq 'running') { write-host "$($_.Name) is started" -ForegroundColor Green } elseif ($_.status -eq 'stopped') { write-host "$($_.Name) is stopped" -ForegroundColor Red } else { write-host "$($_.Name) is $($_.status)" -ForegroundColor Yellow } } Resume-Service workstation #endregion #region: ForEach (Statement/Construct) # ForEach ( $x in $y ) { # <commands> # } # PS 7: Parallel processing # ForEach -Parallel ( $x in $y ) { # <commands> # } $SvcList = Get-service "sp*" ForEach ( $Svc in $SvcList ) { Write-Host "$($Svc.Name) is $($Svc.Status)" } # Foreach Construct is not the same as ForEach-Object Cmdlet !!! $SvcList |ForEach-Object { Write-Host "$($_.Name) is $($_.Status)" } # Wrong ForEach-Object ( $Svc -in $SvcList ) { Write-Host "$($Svc.Name) is $($Svc.Status)" # > ERROR } ForEach ( $Svc in $SvcList ) { Write-Host "$($Svc.Name) is $($Svc.Status)" } #endregion #region: Break the loop: Continue / Break $array = @('1','2','3','4') foreach ($nr in $array) { if ($nr -lt 3 ) { Write-Host "$nr < 3" } Write-Host "$nr >= 3" } ### $array = @('1','2','3','4') foreach ($nr in $array) { if ($nr -lt 3 ) { Write-Host "$nr < 3" continue } Write-Host "$nr >= 3" } ### $array | foreach { if ($_ -lt 3 ) { Write-Host "$_ < 3" Break } Write-Host "$_ >= 3" } #endregion #region: For () {} # Repeat code block while condition is true # For (start; condition; action ) { codeblock } For ($x = 1; $x -le 10; $x++ ) { Write-Host "Line $x" } 1..10 | foreach {Write-Host "Line $_"} 1..10 | Write-Host "Line $_" #> ERROR 1..10 | Write-Host 1..10 help Write-Host -ShowWindow #endregion #region: Do .. While .. Until # Executed at least 1 time # Repeat while condition is True # Do {codeblock} While (condition is true) # Do {...} While (...) $x = 10 Do { Write-Host "Line $x" $x++ } While ($x -le 10) #endregion #region: Do .. Until # Executed at least 1 time # Repeat while condition is False # Do {codeblock} Until (condition is true) $x =0 Do {$x++; Write-Host "Line $x"} until ($x -gt 5) $x =6 Do {$x++; Write-Host "Line $x"} until ($x -gt 5) $x =0 Do {$x++; Write-Host "Line $x"} until ($x -le 5) $x =6 Do {$x++; Write-Host "Line $x"} until ($x -le 5) #endregion #region: While # Executed at least 0 time # While (condition is true) {codeblock} $x =1 While ($x -le 4) { Write-Host "Line $x" $x++ } $x =5 While ($x -le 4) { Write-Host "Line $x" $x++ } # Attention: when condition is already true !! $Menu = "Make a choice" Do {$choice = Read-Host $Menu} While ($choice -notin ('1','2','3','4','5')) While ($choice -notin ('1','2','3','4','5')) {$choice = Read-Host $Menu} Remove-Variable choice While ($choice -notin ('1','2','3','4','5')) {$choice = Read-Host $Menu} <# :red while (<condition1>) { :yellow while (<condition2>) { while (<condition3>) { if ($a) {break} if ($b) {break red} if ($c) {break yellow} } Write-Host "After innermost loop" } Write-Host "After yellow loop" } Write-Host "After red loop" #> $red = 0 $yellow = 0 $green = 0 $breakGreen = $true $breakYellow = $true $breakRed = $true :red while ( $red -le 2 ) { $red++ Write-Host "Red loop $red" -f Red Start-Sleep 1 :yellow while ( $yellow -le 2 ) { $yellow++ Write-Host "`tYellow loop $yellow" -f Yellow Start-Sleep 1 while ( $green -le 2 ) { $green++ Write-Host "`t`tGreen loop $green" -f Green Start-Sleep 1 if ($breakGreen) {break} if ($breakYellow) {break yellow} if ($breakRed) {break red} } Write-Host "`t`tAfter green loop" -f Green } Write-Host "`tAfter yellow loop" -f Yellow } Write-Host "After red loop" -f Red #endregion #region: Switch <# Switch (Variable to test) { 1 {command 1} # multiple values can be true 2 {command 2} Default {action default} } #> $x = 2 Switch ($x) { 1 {Write-Host "Option 1"} 2 {Write-Host "Option 2"} 3 {Write-Host "Option 3"} Default {Write-Host "Something Else"} } $x = 5 Switch ($x) { 1 {Write-Host "Option 1"} 2 {Write-Host "Option 2"} 3 {Write-Host "Option 3"} Default {Write-Host "Something Else"} } #> Option 2 $x = 'Rotterdam' Switch -Wildcard ($x) { *dam {Write-Host "Rotterdam or Amsterdam"} A* {Write-Host "Amsterdam"} R* {Write-Host "Rotterdam"} Default {Write-Host "Somewhere else"} } #> Rotterdam or Amsterdam #> Rotterdam $Size = 465388000000 Switch ($Size) { DEFAULT { $Unit = 1 ; $Symbol = 'B'} {$_ -gt 1KB} { $Unit = 1KB ; $Symbol = 'KB'} {$_ -gt 1MB} { $Unit = 1MB ; $Symbol = 'MB'} {$_ -gt 1GB} { $Unit = 1GB ; $Symbol = 'GB'} } "Total size: {0:N2} $Symbol" -f ($Size/$Unit) #endregion #region: Begin..Proces..End Function Demo-BeginProcessEnd { PARAM ( $Par1, [parameter(ValueFromPipeline=$true)]$Par2, [parameter(ValueFromPipeline=$true)]$Par3 ) Begin{ Write-Host "Start Function: $($MyInvocation.MyCommand)" Write-Host "Begin:`tExecuted once" -ForegroundColor Green Write-Host "=" $i = 1 } Process { Write-Host "Process Pipeline input: $Par2" -BackgroundColor White -ForegroundColor Blue foreach ($p in $Par1) { Write-Host "`t Parameter: $p" } } End{ write-Host "=" Write-Host "End Function: $($MyInvocation.MyCommand)" Write-Host "End:`tExecuted once" -ForegroundColor Red } } cls "ABC", "DEF" | Demo-BeginProcessEnd -Par1 "123", "456", "789" ################## Function Test { begin { $i = 0 } process { "Iteration: $i" $i++ "`tInput: $input, $input" "`tInput: $input" "`tAccess Again: $input" $input.Reset() "`tAfter Reset: $input" } } "one","two" | Test #endregion #region: Demo-Menu: $gsv = 'Get-Service' $gps = 'Get-Process' $msg = $null Function MakeMenu { $Script:Menu= @" Menu --------------------------- `t1.`t$gsv `t2.`t$gps `t3.`tGet System Eventlog `t4.`tCheck Freespace (GB) `t$msg `t5.`tQuit `tSelect an option "@ # @"" = Multi-line string literal with embedded variables. } Do { MakeMenu $msg = $null $choice = Read-Host $Menu Switch ($choice) { 1 {Invoke-Expression $gsv} 2 {Invoke-Expression $gps} 3 {Get-Eventlog -LogName System -Newest 10} 4 {$FreeSpace = '{0:N0}'-f ((Get-CimInstance -ClassName Win32_LogicalDisk -Filter "DeviceId='c:'").FreeSpace/1GB)+" GB" #{((Get-wmiObject -Class Win32_LogicalDisk -Filter "DeviceId='c:'").FreeSpace/1GB)} $msg = "Freespace: $FreeSpace" } 5 {Break} default {Write-Warning "$choice is not a valid choice"} } } While ($choice -ne 5) #endregion |