if (Test-Path $path) {
    Write-Host "File exists."
}
if (!(Test-Path $path)) {
    Write-Host "File does not exist."
}

if ($?) {
	Write-Host 'Success' -ForegroundColor Green
} else {
	Write-Host 'FAILED' -ForegroundColor Red
	throw 'Failed.'
}

Get-ChildItem -Recurse -Path C:\Temp -Include *.txt | Select-String 'This', 'OR that' | Select-String 'AND this' | Format-Table -property path, line -autosize | Out-String -Width 4096

(Get-Content $filename) -replace 'heise', 'Heise' | Set-Content $filename

$timestamp = (Get-Date).ToString("yyyyMMdd HHmmssff")

param (
    [parameter(Mandatory=$true,HelpMessage='The target server')] [string]$targetServer,
    [parameter(Mandatory=$true)] [string]$targetWebConfig,
    [parameter(Mandatory=$false)] [string]$build = 'debug'
)

Push-Location "$($MyInvocation.MyCommand.Path)\..\"
#...
Pop-Location

Search by thumbprint:

Get-ChildItem -Path Cert: -Recurse | Where-Object { $_.Thumbprint -and $_.Thumbprint.ToLower().StartsWith('c4') }

To check if the cert is valid, pipe it the Test-Certificate command:

Get-ChildItem -Path Cert: -Recurse | Where-Object { $_.Thumbprint -and $_.Thumbprint.ToLower().StartsWith('c4') } | Test-Certificate

To check for expired / revoked certs:

$certs = Get-ChildItem -Path Cert:\LocalMachine\My -Recurse
foreach ($cert in $certs) {
    Write-Host "$($cert.Thumbprint) $($cert.Subject)"
 
    if ($certs.NotAfter -lt (Get-Date)) {
        Write-Host "    Expired on $($certs.NotAfter)" -ForegroundColor Red
    }
    elseif ($cert | Test-Certificate) {
        Write-Host "    Tested ok." -ForegroundColor Green
    }
}

1. Run notepad $PROFILE.
2. Add this to the top:

   # Uncomment this to use PowerShellGet
   #$Username="global\heises"
   #$Password="password"
   #[system.net.webrequest]::defaultwebproxy = new-object system.net.webproxy('http://10.104.66.70:80')
   #[system.net.webrequest]::defaultwebproxy.credentials = New-Object System.Net.NetworkCredential($Username, $Password)
   #[system.net.webrequest]::defaultwebproxy.BypassProxyOnLocal = $true

3. Uncomment, fill out the details, and save.
4. Start a new Powershell session.
5. Run Register-PSRepository -Default
6. Run Get-PSRepository again to verify.
7. Once installation is complete, comment out commands and change password.

If this doesn't work, and it won't for an ANZ Dev VM, try the PowerShell Manual Module Installation.

May only work inside Windows Powershell ISE.

$intervalSeconds = 60
$mouseDistance = 1
 
$myshell = New-Object -com "Wscript.Shell"
while ($true) {
    Start-Sleep -Seconds $intervalSeconds
    $Pos = [System.Windows.Forms.Cursor]::Position
    [System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point((($Pos.X) + $mouseDistance) , $Pos.Y)
    [System.Windows.Forms.SendKeys]::SendWait("{f15}")
    Write-Host 'A shuffle to the right.'
    Start-Sleep -Seconds $intervalSeconds
    $Pos = [System.Windows.Forms.Cursor]::Position
    [System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point((($Pos.X) - $mouseDistance) , $Pos.Y)
    [System.Windows.Forms.SendKeys]::SendWait("{f15}")
    Write-Host 'A shuffle to the left.'
}

'1234abcd' -replace '\d', '*' # ****abcd

'123.456.789.123' -match '\d+(?:\.\d+){2}' # returns true if there is a match.
$Matches.Values                            # = '123.456.789'

$inputText = '!! Match me
Not me
!! Match me too
Not me tho'
$regex=[regex] '(?m)^!!.+?$'
$regex.matches($inputText) | Foreach-Object { $_.Value } # Returns a string, one match per line.

# Filter lines by regex.
$inputText = ' .. . . left:10 .  .. right:10 ... 
 .. . . left:20 .  .. right:20 ... 
 .. . left:30 . . ...  .. right:30 ... 
 left:40right:40' -replace "`r`n", "`n"
 
$regex=[regex] '(?m)^[ \.]*(?<left>left:\d+)[ \.]*(?<right>right:\d+)[ \.]*$'
$regex.matches($inputText) | Foreach-Object { $_.Groups["left"].value + ' - ' + $_.Groups["right"].value}
# Returns a string:
#left:10 - right:10
#left:20 - right:20
#left:30 - right:30
#left:40 - right:40

$regex=[regex] ('-rw-rw---- 1 root sdcard_rw (?<length>\d+) (?<date>\d\d\d\d-\d\d-\d\d \d\d:\d\d) (?<filename>.*)$')
$input='-rw-rw---- 1 root sdcard_rw 358 2019-09-01 19:50 /storage/emulated/0/Podcasts/Sync Test/New folder/rua.txt'
$matches = $regex.matches($input)
if (!($matches.Success)) {
	Write-Host "Regex failed to match: $input" -ForegroundColor Red
	Exit(-1)
}
Write-Host "length   = $($matches.Captures.Groups["length"].value)"
Write-Host "date     = $($matches.Captures.Groups["date"].value)"
Write-Host "filename = $($matches.Captures.Groups["filename"].value)"

# $1 = group 1, $2 = group 2, etc.
'123 456 789' -replace '(\d+ )(\d+)( \d+)', '$1!$2!$3'  # = '123 !456! 789'

function Replace-String {
    [cmdletbinding()]
    Param (
        [parameter(ValueFromPipeline)]
        [string]$Input,
        [string]$OldValue,
        [string]$NewValue
    )
 
    Process {
        $Input -replace $OldValue, $NewValue
    }
}
 
'djkslajklfdsjkl' | Replace-String -OldValue 'd' -NewValue 'x'