PowerShell 7 Cheatsheet: Cmdlets, Pipelines, Objects and Modules

# Install PowerShell 7 (cross-platform)
brew install --cask powershell                   # macOS
winget install --id Microsoft.PowerShell         # Windows
sudo apt install -y powershell                   # Debian/Ubuntu (via packages.microsoft.com)

# Versions
pwsh -v                                          # PowerShell 7.x (cross-platform "Core")
powershell -v                                    # Windows PowerShell 5.1 (Windows only, legacy)

# Profile (per-host)
notepad $PROFILE                                 # opens $HOME/.config/PowerShell/Microsoft.PowerShell_profile.ps1
. $PROFILE                                       # reload without restarting

# Run a script
pwsh ./build.ps1
pwsh -File ./build.ps1 -ConfigPath ./prod.json

# Daily commands
Get-Help Get-ChildItem -Examples                 # docs + examples
Get-Command -Module Az                           # list cmdlets in a module
Update-Help                                      # refresh help locally

# Everything in the pipeline is an OBJECT — not text.
# That's the single difference that explains all the rest.

# Get the 5 biggest files in the current tree
Get-ChildItem -Recurse -File `
  | Sort-Object Length -Descending `
  | Select-Object -First 5 -Property FullName, Length

# Filter + project + group + summarize
Get-Process `
  | Where-Object   { $_.WS -gt 100MB } `
  | Select-Object  Name, @{ n='WS_MB'; e={ [math]::Round($_.WS/1MB, 1) } } `
  | Sort-Object    WS_MB -Descending `
  | Format-Table   -AutoSize

# Group then aggregate (like SQL GROUP BY)
Get-ChildItem -Recurse -File `
  | Group-Object   Extension `
  | Sort-Object    Count -Descending `
  | Select-Object  -First 5 Name, Count, `
                   @{ n='SizeMB'; e={ [math]::Round(($_.Group | Measure-Object Length -Sum).Sum / 1MB, 1) } }

# Export anywhere
Get-Process | Select-Object Name, Id, WS | Export-Csv ./procs.csv -NoTypeInformation
Get-Process | ConvertTo-Json | Out-File ./procs.json

# Advanced function with typed parameters, pipeline input, and validation

function Get-LargeFile {
    [CmdletBinding()]
    [OutputType([System.IO.FileInfo])]
    param(
        [Parameter(Mandatory, Position = 0, ValueFromPipeline)]
        [ValidateScript({ Test-Path $_ })]
        [string] $Path,

        [ValidateRange(1, [int]::MaxValue)]
        [int] $MinSizeMB = 10,

        [switch] $Recurse
    )

    process {
        $bytes = $MinSizeMB * 1MB
        Get-ChildItem -Path $Path -File -Recurse:$Recurse `
          | Where-Object { $_.Length -ge $bytes }
    }
}

# Call it
Get-LargeFile -Path . -MinSizeMB 50 -Recurse

# Pipeline-style
"." | Get-LargeFile -MinSizeMB 25 -Recurse

# Splatting — pass a hashtable of args
$params = @{
    Path        = '.'
    MinSizeMB   = 100
    Recurse     = $true
}
Get-LargeFile @params

# Concurrent REST calls + parsed objects + grouped output
# Requires PowerShell 7+ (ForEach-Object -Parallel)

$owners = 'PowerShell', 'microsoft', 'github'

$results = $owners | ForEach-Object -Parallel {
    $owner = $_
    try {
        $repos = Invoke-RestMethod `
            -Uri "https://api.github.com/users/$owner/repos?per_page=5" `
            -Headers @{ 'User-Agent' = 'devshelf' } `
            -TimeoutSec 5

        $repos | Select-Object `
            @{ n = 'Owner';  e = { $owner } }, `
            @{ n = 'Name';   e = { $_.name } }, `
            @{ n = 'Stars';  e = { $_.stargazers_count } }, `
            @{ n = 'Lang';   e = { $_.language } }
    }
    catch {
        Write-Warning "$owner failed: $($_.Exception.Message)"
    }
} -ThrottleLimit 4

# Group + summarize
$results `
  | Group-Object Owner `
  | ForEach-Object {
        $totalStars = ($_.Group | Measure-Object Stars -Sum).Sum
        [pscustomobject]@{ Owner = $_.Name; Repos = $_.Count; TotalStars = $totalStars }
    } `
  | Sort-Object TotalStars -Descending `
  | Format-Table -AutoSize

# Persist to JSON
$results | ConvertTo-Json -Depth 4 | Out-File ./repos.json