Tips and Tricks

Author : MD TAREQ HASSAN | Updated : 2021/09/25

Run a script in PowerShell cli

Open PowerShell as administrator
cd [target folder] (in which script is located)
./[script_name].ps1 > Enter

Get function name

$MyInvocation.MyCommand.Name (gives function name when used inside a function)

$rgResourceId = ''
try {
    $rgResourceId = (Get-AzResourceGroup -Name $Name -ErrorAction Stop).ResourceId
}
catch {
    $exceptionMessage = $Error[0].Exception.Message.Split("-")[1].Trim()
    Write-Warning "[at function $($MyInvocation.MyCommand.Name)] -> Exception message: $exceptionMessage"
}

# To use script name too: $(Split-Path -Path $PSCommandPath -Leaf)
# Write-Warning "[$(Split-Path -Path $PSCommandPath -Leaf) at function $($MyInvocation.MyCommand.Name)] -> Exception message: $exceptionMessage"

Return single value from function and script

PowerShell function and script returns all uncaptured output
- Write-Output
- return (when a script returns value, and you are executing that script)
- Any variable $x just sitting there
- etc.
Write-Output (alias: Echo) will send message as an Object through the pipeline. On the other hand Write-Host/Write-Warning/Write-Error is only console-messages. so:
- For normal messages, use Write-Output
- For exception or error mesaages, use Write-Warning/Write-Error

function test {

    # do somethings here
    $x = 10
    
    # Use -> Write-Host or Write-Warning or Write-Error
    # Do Not Use -> Write-Output
    
    return x
}

$returnedVal = test
#returnedVal: 10

StackOverflow question: https://stackoverflow.com/questions/29556437/how-to-return-one-and-only-one-value-from-a-powershell-function

Show progress

-Verbose flag will show updates when performing operation

$name = 'rg-xxx'
try {

    Remove-AzResourceGroup -Name $name -Force -Verbose -ErrorAction Stop

    Write-Host "Resource group '$Name' was deleted successfully`n"
}
catch {
    $exceptionMessage = $Error[0].Exception.Message.Split("-")[1].Trim()
    Write-Warning "Failed to delete resource group '$Name' (Error: $exceptionMessage)`n"
}

Using “-AsJob” and for loop

$getSaSplat = @{
    Name              = $saName
    ResourceGroupName = $rgName
}

$sa = $null
try {
    $sa = Get-AzStorageAccount @getSaSplat -ErrorAction Stop
}
catch {
    Write-Warning $Error[0]
}

if ($null -eq $sa) {

    $newSaSplat = $getSaSplat + @{
        Location = $rgLocation
        SkuName  = $saSku
        Kind     = $saKind
    }

    try {

        Write-Host "Stoarge Account '$saName' does not exist, creating new...`r`n"

        New-AzStorageAccount @newSaSplat -Tag $tagsHashTable -ErrorAction Stop -AsJob | Out-Null

        Write-Host "`r`n-------------------------------------------------------------------------------------------`r`n"

        #Start-Sleep -Seconds 1

        $sa = Get-AzStorageAccount @getSaSplat -ErrorAction SilentlyContinue
    
        while ('Succeeded' -ne ${sa}?.ProvisioningState) {
            Write-Host "[$(Get-Date -DisplayHint Time)] Storage account is not created yet -> ProvisioningState: $(${sa}?.ProvisioningState) `r`n"
            Start-Sleep -Seconds 3
            $sa = Get-AzStorageAccount @getSaSplat -ErrorAction SilentlyContinue
        }   
    
        Write-Host "`r`n-------------------------------------------------------------------------------------------`r`n"
        Write-Host "Stoarge Account '$saName' has been created `r`n"

    }
    catch {
        Write-Warning $Error[0]
    }
}
else {
    
    Write-Host "Stoarge Account '$saName' already exists `r`n"
}

Keep Shell Window Open After Running Script

$xyz = ""
# ... ... ...
echo $xyz

#
# Per-script Fix: Add a prompt for input to the end of your script file. e.g. Read-Host -Prompt "Press Enter to exit"
#
Read-Host -Prompt "Press Enter to exit"

StackOverflow answer: https://stackoverflow.com/a/24620771/4802664

Test SQL Server Connetion

#
# Collected from: https://mcpmag.com/articles/2018/12/10/test-sql-connection-with-powershell.aspx
#

function Test-SqlConnection {
    param(
        [Parameter(Mandatory)]
        [string]$ServerName,

        [Parameter(Mandatory)]
        [string]$DatabaseName,

        [Parameter(Mandatory)]
        [pscredential]$Credential
    )

    $ErrorActionPreference = 'Stop'

    try {
        $userName = $Credential.UserName
        $password = $Credential.GetNetworkCredential().Password
        $connectionString = 'Data Source={0};database={1};User ID={2};Password={3}' -f $ServerName,$DatabaseName,$userName,$password
        $sqlConnection = New-Object System.Data.SqlClient.SqlConnection $ConnectionString
        $sqlConnection.Open()
        ## This will run if the Open() method does not throw an exception
        $true
    } catch {
        $false
    } finally {
        ## Close the connection when we're done
        $sqlConnection.Close()
    }
}

#
# Get server instance (Computer\Instance), run follwoing command in SSMS
# SELECT @@servername + '\' + @@servicename
# Get server name only: SELECT @@servername
#
Test-SqlConnection -ServerName 'SqlServerName' -DatabaseName 'AdventureWorksLT2019' -Credential (Get-Credential)

Surpressing output

New-Item -Path 'c:\newfolder' -ItemType Directory | Out-Null

# https://stackoverflow.com/a/51698384/4802664
Out-Null -InputObject ($(1..1000) | ?{$_ -is [int]})

#
# Note
# [x] | Out-Null -> one at a time
# Out-Null -InputObject [x] -> whole thing as a single object
#

Get help

Get-Help [command]
Get-Help [command] -Full
Get-Help [command] -Parameter *

# Examples
Get-Help Start-Service -Full
Get-Help Start-Service -Parameter *