Category Power Shell

Cheat Sheet 1

Get-Command                                    # List of all the commands available to PowerShell
                                               # (native binaries in $env:PATH + cmdlets / functions from PowerShell modules)
Get-Command -Module Microsoft*                 # Lst of all the PowerShell commands exported from modules named Microsoft*
Get-Command -Name *item                        # List of all commands ending in "item"

Get-Help                                       # Get all help topics
Get-Help -Name about_Variables                 # Get help for a specific about_* topic (aka. man page)
Get-Help -Name Get-Command                     # Get help for a specific PowerShell function
Get-Help -Name Get-Command -Parameter Module   # Get help for a specific parameter on a specific command

###################################################
# Operators
###################################################

$a = 2                                                    # Basic variable assignment operator
$a += 1                                                   # Incremental assignment operator
$a -= 1                                                   # Decrement assignment operator

$a -eq 0                                                  # Equality comparison operator
$a -ne 5                                                  # Not-equal comparison operator
$a -gt 2                                                  # Greater than comparison operator
$a -lt 3                                                  # Less than comparison operator

$FirstName = 'Trevor'
$FirstName -like 'T*'                                     # Perform string comparison using the -like operator, which supports the wildcard (*) character. Returns $true

$BaconIsYummy = $true
$FoodToEat = $BaconIsYummy ? 'bacon' : 'beets'            # Sets the $FoodToEat variable to 'bacon' using the ternary operator

'Celery' -in @('Bacon', 'Sausage', 'Steak', 'Chicken')    # Returns boolean value indicating if left-hand operand exists in right-hand array
'Celery' -notin @('Bacon', 'Sausage', 'Steak')            # Returns $true, because Celery is not part of the right-hand list

5 -is [string]                                            # Is the number 5 a string value? No. Returns $false.
5 -is [int32]                                             # Is the number 5 a 32-bit integer? Yes. Returns $true.
5 -is [int64]                                             # Is the number 5 a 64-bit integer? No. Returns $false.
'Trevor' -is [int64]                                      # Is 'Trevor' a 64-bit integer? No. Returns $false.
'Trevor' -isnot [string]                                  # Is 'Trevor' NOT a string? No. Returns $false.
'Trevor' -is [string]                                     # Is 'Trevor' a string? Yes. Returns $true.
$true -is [bool]                                          # Is $true a boolean value? Yes. Returns $true.
$false -is [bool]                                         # Is $false a boolean value? Yes. Returns $true.
5 -is [bool]                                              # Is the number 5 a boolean value? No. Returns $false.
/pre>

###################################################
# Regular Expressions
###################################################

'Trevor' -match '^T\w*'                                   # Perform a regular expression match against a string value. # Returns $true and populates $matches variable
$matches[0]                                               # Returns 'Trevor', based on the above match

@('Trevor', 'Billy', 'Bobby') -match '^B'                 # Perform a regular expression match against an array of string values. Returns Billy, Bobby

$regex = [regex]'(\w{3,8})'
$regex.Matches('Trevor Bobby Dillon Joe Jacob').Value     # Find multiple matches against a singleton string value.
/pre>

###################################################
# Flow Control
###################################################

if (1 -eq 1) { }                                          # Do something if 1 is equal to 1

do { 'hi' } while ($false)                                # Loop while a condition is true (always executes at least once)

while ($false) { 'hi' }                                   # While loops are not guaranteed to run at least once
while ($true) { }                                         # Do something indefinitely
while ($true) { if (1 -eq 1) { break } }                  # Break out of an infinite while loop conditionally

for ($i = 0; $i -le 10; $i++) { Write-Host $i }           # Iterate using a for..loop
foreach ($item in (Get-Process)) { }                      # Iterate over items in an array

switch ('test') { 'test' { 'matched'; break } }           # Use the switch statement to perform actions based on conditions. Returns string 'matched'
switch -regex (@('Trevor', 'Daniel', 'Bobby')) {          # Use the switch statement with regular expressions to match inputs
  'o' { $PSItem; break }                                  # NOTE: $PSItem or $_ refers to the "current" item being matched in the array
}
switch -regex (@('Trevor', 'Daniel', 'Bobby')) {          # Switch statement omitting the break statement. Inputs can be matched multiple times, in this scenario.
  'e' { $PSItem }
  'r' { $PSItem }
}
/pre>

###################################################
# Variables
###################################################


$a = 0                                                    # Initialize a variable
[int] $a = 'Trevor'                                       # Initialize a variable, with the specified type (throws an exception)
[string] $a = 'Trevor'                                    # Initialize a variable, with the specified type (doesn't throw an exception)

Get-Command -Name *varia*                                 # Get a list of commands related to variable management

Get-Variable                                              # Get an array of objects, representing the variables in the current and parent scopes 
Get-Variable | ? { $PSItem.Options -contains 'constant' } # Get variables with the "Constant" option set
Get-Variable | ? { $PSItem.Options -contains 'readonly' } # Get variables with the "ReadOnly" option set

New-Variable -Name FirstName -Value Trevor
New-Variable FirstName -Value Trevor -Option Constant     # Create a constant variable, that can only be removed by restarting PowerShell
New-Variable FirstName -Value Trevor -Option ReadOnly     # Create a variable that can only be removed by specifying the -Force parameter on Remove-Variable

Remove-Variable -Name firstname                           # Remove a variable, with the specified name
Remove-Variable -Name firstname -Force                    # Remove a variable, with the specified name, that has the "ReadOnly" option set
/pre>

###################################################
# Functions
###################################################

function add ($a, $b) { $a + $b }                         # A basic PowerShell function

function Do-Something {                                   # A PowerShell Advanced Function, with all three blocks declared: BEGIN, PROCESS, END
  [CmdletBinding]()]
  param ()
  begin { }
  process { }
  end { }
}
/pre>

###################################################
# Working with Modules
###################################################

Get-Command -Name *module* -Module mic*core                 # Which commands can I use to work with modules?

Get-Module -ListAvailable                                   # Show me all of the modules installed on my system (controlled by $env:PSModulePath)
Get-Module                                                  # Show me all of the modules imported into the current session

$PSModuleAutoLoadingPreference = 0                          # Disable auto-loading of installed PowerShell modules, when a command is invoked

Import-Module -Name NameIT                                  # Explicitly import a module, from the specified filesystem path or name (must be present in $env:PSModulePath)
Remove-Module -Name NameIT                                  # Remove a module from the scope of the current PowerShell session

New-ModuleManifest                                          # Helper function to create a new module manifest. You can create it by hand instead.

New-Module -Name trevor -ScriptBlock {                      # Create an in-memory PowerShell module (advanced users)
  function Add($a,$b) { $a + $b } }

New-Module -Name trevor -ScriptBlock {                      # Create an in-memory PowerShell module, and make it visible to Get-Module (advanced users)
  function Add($a,$b) { $a + $b } } | Import-Module
/pre>

###################################################
# Module Management
###################################################

Get-Command -Module PowerShellGet                           # Explore commands to manage PowerShell modules

Find-Module -Tag cloud                                      # Find modules in the PowerShell Gallery with a "cloud" tag
Find-Module -Name ps*                                       # Find modules in the PowerShell Gallery whose name starts with "PS"

Install-Module -Name NameIT -Scope CurrentUser -Force       # Install a module to your personal directory (non-admin)
Install-Module -Name NameIT -Force                          # Install a module to your personal directory (admin / root)
Install-Module -Name NameIT -RequiredVersion 1.9.0          # Install a specific version of a module

Uninstall-Module -Name NameIT                               # Uninstall module called "NameIT", only if it was installed via Install-Module

Register-PSRepository -Name <repo> -SourceLocation <uri>    # Configure a private PowerShell module registry
Unregister-PSRepository -Name <repo>                        # Deregister a PowerShell Repository
/pre>

###################################################
# Filesystem
###################################################

New-Item -Path c:\test -ItemType Directory                  # Create a directory
mkdir c:\test2                                              # Create a directory (short-hand)

New-Item -Path c:\test\myrecipes.txt                        # Create an empty file
Set-Content -Path c:\test.txt -Value ''                     # Create an empty file
[System.IO.File]::WriteAllText('testing.txt', '')           # Create an empty file using .NET Base Class Library

Remove-Item -Path testing.txt                               # Delete a file
[System.IO.File]::Delete('testing.txt')                     # Delete a file using .NET Base Class Library
/pre>

###################################################
# Hashtables (Dictionary)
###################################################

$Person = @{
  FirstName = 'Trevor'
  LastName = 'Sullivan'
  Likes = @(
    'Bacon',
    'Beer',
    'Software'
  )
}                                                           # Create a PowerShell HashTable

$Person.FirstName                                           # Retrieve an item from a HashTable
$Person.Likes[-1]                                           # Returns the last item in the "Likes" array, in the $Person HashTable (software)
$Person.Age = 50                                            # Add a new property to a HashTable
/pre>

###################################################
# Windows Management Instrumentation (WMI) (Windows only)
###################################################

Get-CimInstance -ClassName Win32_BIOS                       # Retrieve BIOS information
Get-CimInstance -ClassName Win32_DiskDrive                  # Retrieve information about locally connected physical disk devices
Get-CimInstance -ClassName Win32_PhysicalMemory             # Retrieve information about install physical memory (RAM)
Get-CimInstance -ClassName Win32_NetworkAdapter             # Retrieve information about installed network adapters (physical + virtual)
Get-CimInstance -ClassName Win32_VideoController            # Retrieve information about installed graphics / video card (GPU)

Get-CimClass -Namespace root\cimv2                          # Explore the various WMI classes available in the root\cimv2 namespace
Get-CimInstance -Namespace root -ClassName __NAMESPACE      # Explore the child WMI namespaces underneath the root\cimv2 namespace
/pre>

###################################################
# Asynchronous Event Registration
###################################################

#### Register for filesystem events
$Watcher = [System.IO.FileSystemWatcher]::new('c:\tmp')
Register-ObjectEvent -InputObject $Watcher -EventName Created -Action {
  Write-Host -Object 'New file created!!!'
}                                                           

#### Perform a task on a timer (ie. every 5000 milliseconds)
$Timer = [System.Timers.Timer]::new(5000)
Register-ObjectEvent -InputObject $Timer -EventName Elapsed -Action {
  Write-Host -ForegroundColor Blue -Object 'Timer elapsed! Doing some work.'
}
$Timer.Start()
/pre>

###################################################
# PowerShell Drives (PSDrives)
###################################################

Get-PSDrive                                                 # List all the PSDrives on the system
New-PSDrive -Name videos -PSProvider Filesystem -Root x:\data\content\videos  # Create a new PSDrive that points to a filesystem location
New-PSDrive -Name h -PSProvider FileSystem -Root '\\storage\h$\data' -Persist # Create a persistent mount on a drive letter, visible in Windows Explorer
Set-Location -Path videos:                                  # Switch into PSDrive context
Remove-PSDrive -Name xyz                                    # Delete a PSDrive
/pre>

###################################################
# Data Management
###################################################

Get-Process | Group-Object -Property Name                   # Group objects by property name
Get-Process | Sort-Object -Property Id                      # Sort objects by a given property name
Get-Process | Where-Object -FilterScript { $PSItem.Name -match '^c' } # Filter objects based on a property matching a value
gps | where Name -match '^c'                                # Abbreviated form of the previous statement
/pre>

###################################################
# PowerShell Classes
###################################################

class Person {
  [string] $FirstName                                       # Define a class property as a string
  [string] $LastName = 'Sullivan'                           # Define a class property with a default value
  [int] $Age                                                # Define a class property as an integer
  
  Person() {                                                # Add a default constructor (no input parameters) for a class
  }
  
  Person([string] $FirstName) {                             # Define a class constructor with a single string parameter
    $this.FirstName = $FirstName
  }
  
  [string] FullName() {
    return '{0} {1}' -f $this.FirstName, $this.LastName
  }
}
$Person01 = [Person]::new()                                 # Instantiate a new Person object.
$Person01.FirstName = 'Trevor'                              # Set the FirstName property on the Person object.
$Person01.FullName()                                        # Call the FullName() method on the Person object. Returns 'Trevor Sullivan'


class Server {                                              # Define a "Server" class, to manage remote servers. Customize this based on your needs.
  [string] $Name
  [System.Net.IPAddress] $IPAddress                         # Define a class property as an IPaddress object
  [string] $SSHKey = "$HOME/.ssh/id_rsa"                    # Set the path to the private key used to authenticate to the server
  [string] $Username                                        # Set the username to login to the remote server with
  
  RunCommand([string] $Command) {                           # Define a method to call a command on the remote server, via SSH
    ssh -i $this.SSHKey $this.Username@$this.Name $this.Command
  }
}

$Server01 = [Server]::new()                                 # Instantiate the Server class as a new object
$Server01.Name = 'webserver01.local'                        # Set the "name" of the remote server
$Server01.Username = 'root'                                 # Set the username property of the "Server" object
$Server01.RunCommand("hostname")                            # Run a command on the remote server
/pre>

###################################################
# REST APIs
###################################################

$Params = @{
  Uri = 'https://api.github.com/events'
  Method = 'Get'
}
Invoke-RestMethod @Params                                   # Call a REST API, using the HTTP GET method

Learning Powershell in 5 Minutes

Comments

# Single line comments start with a number symbol.

<#
  Multi-line comments
  like so
#>
/pre>

Primitive Datatypes and Operators

####################################################
## 1. Primitive Datatypes and Operators
####################################################

# Numbers
3 # => 3

# Math
1 + 1   # => 2
8 - 1   # => 7
10 * 2  # => 20
35 / 5  # => 7.0

# Powershell uses banker's rounding,
# meaning [int]1.5 would round to 2 but so would [int]2.5
# Division always returns a float. 
# You must cast result to [int] to round.
[int]5 / [int]3       # => 1.66666666666667
[int]-5 / [int]3      # => -1.66666666666667
5.0 / 3.0   # => 1.66666666666667
-5.0 / 3.0  # => -1.66666666666667
[int]$result = 5 / 3 
$result # => 2

# Modulo operation
7 % 3  # => 1

# Exponentiation requires longform or the built-in [Math] class.
[Math]::Pow(2,3)  # => 8

# Enforce order of operations with parentheses.
1 + 3 * 2  # => 7
(1 + 3) * 2  # => 8

# Boolean values are primitives (Note: the $)
$True  # => True
$False  # => False

# negate with !
!$True   # => False
!$False  # => True

# Boolean Operators
# Note "-and" and "-or" usage
$True -and $False  # => False
$False -or $True   # => True

# True and False are actually 1 and 0 but only support limited arithmetic.
# However, casting the bool to int resolves this.
$True + $True # => 2
$True * 8    # => '[System.Boolean] * [System.Int32]' is undefined
[int]$True * 8 # => 8
$False - 5   # => -5

# Comparison operators look at the numerical value of True and False.
0 -eq $False  # => True
1 -eq $True   # => True
2 -eq $True   # => False
-5 -ne $False # => True

# Using boolean logical operators on ints casts to booleans for evaluation.
# but their non-cast value is returned
# Don't mix up with bool(ints) and bitwise -band/-bor
[bool](0)     # => False
[bool](4)     # => True
[bool](-6)    # => True
0 -band 2     # => 0
-5 -bor 0     # => -5

# Equality is -eq (equals)
1 -eq 1  # => True
2 -eq 1  # => False

# Inequality is -ne (notequals)
1 -ne 1  # => False
2 -ne 1  # => True

# More comparisons
1 -lt 10  # => True
1 -gt 10  # => False
2 -le 2  # => True
2 -ge 2  # => True

# Seeing whether a value is in a range
1 -lt 2 -and 2 -lt 3  # => True
2 -lt 3 -and 3 -lt 2  # => False

# (-is vs. -eq) -is checks if two objects are the same type.
# -eq checks if the objects have the same values.
# Note: we called '[Math]' from .NET previously without the preceeding
# namespaces. We can do the same with [Collections.ArrayList] if preferred.
[System.Collections.ArrayList]$a = @()  # Point a at a new list
$a = (1,2,3,4)
$b = $a                                 # => Point b at what a is pointing to
$b -is $a.GetType()                     # => True, a and b equal same type
$b -eq $a                               # => True, a and b values are equal
[System.Collections.Hashtable]$b = @{}  # => Point a at a new hash table
$b = @{'one' = 1 
       'two' = 2}
$b -is $a.GetType()                     # => False, a and b types not equal

# Strings are created with " or ' but " is required for string interpolation
"This is a string."
'This is also a string.'

# Strings can be added too! But try not to do this.
"Hello " + "world!"  # => "Hello world!"

# A string can be treated like a list of characters
"Hello world!"[0]  # => 'H'

# You can find the length of a string
("This is a string").Length  # => 16

# You can also format using f-strings or formatted string literals.
$name = "Steve"
$age = 22
"He said his name is $name." 
# => "He said his name is Steve"
"{0} said he is {1} years old." -f $name, $age 
# => "Steve said he is 22 years old"
"$name's name is $($name.Length) characters long." 
# => "Steve's name is 5 characters long."

# Escape Characters in Powershell
# Many languages use the '\', but Windows uses this character for 
# file paths. Powershell thus uses '`' to escape characters
# Take caution when working with files, as '`' is a
# valid character in NTFS filenames.
"Showing`nEscape Chars" # => new line between Showing and Escape
"Making`tTables`tWith`tTabs" # => Format things with tabs

# Negate pound sign to prevent comment
# Note that the function of '#' is removed, but '#' is still present
`#Get-Process # => Fail: not a recognized cmdlet

# $null is not an object
$null  # => None

# $null, 0, and empty strings and arrays all evaluate to False.
# All other values are True
function Test-Value ($value) {
  if ($value) {
    Write-Output 'True'
  }
  else {
    Write-Output 'False'
  }
}

Test-Value ($null) # => False
Test-Value (0)     # => False
Test-Value ("")    # => False
Test-Value []      # => True 
# *[] calls .NET class; creates '[]' string when passed to function
Test-Value ({})    # => True
Test-Value @()     # => False

/pre>

####################################################
## 2. Variables and Collections
####################################################

# Powershell uses the "Write-Output" function to print
Write-Output "I'm Posh. Nice to meet you!"  # => I'm Posh. Nice to meet you!

# Simple way to get input data from console
$userInput = Read-Host "Enter some data: " # Returns the data as a string

# There are no declarations, only assignments.
# Convention is to use camelCase or PascalCase, whatever your team uses.
$someVariable = 5
$someVariable  # => 5

# Accessing a previously unassigned variable does not throw exception.
# The value is $null by default

# Ternary Operators exist in Powershell 7 and up
0 ? 'yes' : 'no'  # => no


# The default array object in Powershell is an fixed length array.
$defaultArray = "thing","thing2","thing3"
# you can add objects with '+=', but cannot remove objects.
$defaultArray.Add("thing4") # => Exception "Collection was of a fixed size."
# To have a more workable array, you'll want the .NET [ArrayList] class
# It is also worth noting that ArrayLists are significantly faster

# ArrayLists store sequences
[System.Collections.ArrayList]$array = @()
# You can start with a prefilled ArrayList
[System.Collections.ArrayList]$otherArray = @(4, 5, 6)

# Add to the end of a list with 'Add' (Note: produces output, append to $null)
$array.Add(1) > $null    # $array is now [1]
$array.Add(2) > $null    # $array is now [1, 2]
$array.Add(4) > $null    # $array is now [1, 2, 4]
$array.Add(3) > $null    # $array is now [1, 2, 4, 3]
# Remove from end with index of count of objects-1; array index starts at 0
$array.RemoveAt($array.Count-1) # => 3 and array is now [1, 2, 4]
# Let's put it back
$array.Add(3) > $null   # array is now [1, 2, 4, 3] again.

# Access a list like you would any array
$array[0]   # => 1
# Look at the last element
$array[-1]  # => 3

# Looking out of bounds returns nothing
$array[4]  # blank line returned

# You can look at ranges with slice syntax.
# The start index is included, the end index is not
# (It's a closed/open range for you mathy types.)
$array[1..3]   # Return array from index 1 to 3 => [2, 4]
$array[2..-1]    # Return array starting from index 2 => [4, 3]
$array[0..3]    # Return array from beginning until index 3  => [1, 2, 4]
$array[0..2]   # Return array selecting every second entry => [1, 4]
$array.Reverse()  # mutates array to reverse order => [3, 4, 2, 1]
# Use any combination of these to make advanced slices

# Remove arbitrary elements from a array with "del"
$array.Remove($array[2])  # $array is now [1, 2, 3]

# Insert an element at a specific index
$array.Insert(1, 2)  # $array is now [1, 2, 3] again

# Get the index of the first item found matching the argument
$array.IndexOf(2)  # => 1
$array.IndexOf(6)  # Returns -1 as "outside array" 

# You can add arrays
# Note: values for $array and for $otherArray are not modified.
$array + $otherArray  # => [1, 2, 3, 4, 5, 6]

# Concatenate arrays with "AddRange()"
$array.AddRange($otherArray)  # Now $array is [1, 2, 3, 4, 5, 6]

# Check for existence in a array with "in"
1 -in $array  # => True

# Examine length with "Count" (Note: "Length" on arrayList = each items length)
$array.Count  # => 6


# Tuples are like arrays but are immutable.
# To use Tuples in powershell, you must use the .NET tuple class.
$tuple = [System.Tuple]::Create(1, 2, 3)
$tuple.Item(0)      # => 1
$tuple.Item(0) = 3  # Raises a TypeError

# You can do some of the array methods on tuples, but they are limited.
$tuple.Length       # => 3
$tuple + (4, 5, 6)  # => Exception
$tuple[0..2]        # => $null
2 -in $tuple        # => False


# Hashtables store mappings from keys to values, similar to Dictionaries.
$emptyHash = @{}
# Here is a prefilled dictionary
$filledHash = @{"one"= 1 
                "two"= 2 
                "three"= 3}

# Look up values with []
$filledHash["one"]  # => 1

# Get all keys as an iterable with ".Keys".
# items maintain the order at which they are inserted into the dictionary.
$filledHash.Keys  # => ["one", "two", "three"]

# Get all values as an iterable with ".Values".
$filledHash.Values  # => [1, 2, 3]

# Check for existence of keys or values in a hash with "-in"
"one" -in $filledHash.Keys  # => True
1 -in $filledHash.Values    # => False

# Looking up a non-existing key returns $null
$filledHash["four"]  # $null

# Adding to a dictionary
$filledHash.Add("five",5)  # $filledHash["five"] is set to 5
$filledHash.Add("five",6)  # exception "Item with key "five" has already been added"
$filledHash["four"] = 4 # $filledHash["four"] is set to 4, running again does nothing

# Remove keys from a dictionary with del
$filledHash.Remove("one") # Removes the key "one" from filled dict

/pre>

####################################################
## 3. Control Flow and Iterables
####################################################

# Let's just make a variable
$someVar = 5

# Here is an if statement.
# This prints "$someVar is smaller than 10"
if ($someVar -gt 10) {
    Write-Output "$someVar is bigger than 10."
}
elseif ($someVar -lt 10) {    # This elseif clause is optional.
    Write-Output "$someVar is smaller than 10."
}
else {                        # This is optional too.
    Write-Output "$someVar is indeed 10."
}


<#
Foreach loops iterate over arrays
prints:
    dog is a mammal
    cat is a mammal
    mouse is a mammal
#>
foreach ($animal in ("dog", "cat", "mouse")) {
    # You can use -f to interpolate formatted strings
    "{0} is a mammal" -f $animal
}

<#
For loops iterate over arrays and you can specify indices
prints:
   0 a
   1 b
   2 c
   3 d
   4 e
   5 f
   6 g
   7 h
#>
$letters = ('a','b','c','d','e','f','g','h')
for($i=0; $i -le $letters.Count-1; $i++){
    Write-Host $i, $letters[$i]
}

<#
While loops go until a condition is no longer met.
prints:
    0
    1
    2
    3
#>
$x = 0
while ($x -lt 4) {
    Write-Output $x
    $x += 1  # Shorthand for x = x + 1
}

# Switch statements are more powerful compared to most languages
$val = "20"
switch($val) {
  { $_ -eq 42 }           { "The answer equals 42"; break }
  '20'                    { "Exactly 20"; break }
  { $_ -like 's*' }       { "Case insensitive"; break }
  { $_ -clike 's*'}       { "clike, ceq, cne for case sensitive"; break }
  { $_ -notmatch '^.*$'}  { "Regex matching. cnotmatch, cnotlike, ..."; break }
  default                 { "Others" }
}

# Handle exceptions with a try/catch block
try {
    # Use "throw" to raise an error
    throw "This is an error"
}
catch {
    Write-Output $Error.ExceptionMessage
}
finally {
    Write-Output "We can clean up resources here"
}


# Writing to a file
$contents = @{"aa"= 12 
             "bb"= 21}
$contents | Export-CSV "$env:HOMEDRIVE\file.csv" # writes to a file

$contents = "test string here"
$contents | Out-File "$env:HOMEDRIVE\file.txt" # writes to another file

# Read file contents and convert to json
Get-Content "$env:HOMEDRIVE\file.csv" | ConvertTo-Json

/pre>

####################################################
## 4. Functions
####################################################

# Use "function" to create new functions
# Keep the Verb-Noun naming convention for functions
function Add-Numbers {
 $args[0] + $args[1]
}

Add-Numbers 1 2 # => 3

# Calling functions with parameters
function Add-ParamNumbers {
 param( [int]$firstNumber, [int]$secondNumber )
 $firstNumber + $secondNumber
}

Add-ParamNumbers -FirstNumber 1 -SecondNumber 2 # => 3 

# Functions with named parameters, parameter attributes, parsable documentation
<#
.SYNOPSIS
Setup a new website
.DESCRIPTION
Creates everything your new website needs for much win
.PARAMETER siteName
The name for the new website
.EXAMPLE
New-Website -Name FancySite -Po 5000
New-Website SiteWithDefaultPort
New-Website siteName 2000 # ERROR! Port argument could not be validated
('name1','name2') | New-Website -Verbose
#>
function New-Website() {
    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline=$true, Mandatory=$true)]
        [Alias('name')]
        [string]$siteName,
        [ValidateSet(3000,5000,8000)]
        [int]$port = 3000
    )
    BEGIN { Write-Output 'Creating new website(s)' }
    PROCESS { Write-Output "name: $siteName, port: $port" }
    END { Write-Output 'Website(s) created' }
}
/pre>

####################################################
## 5. Modules
####################################################

# You can import modules and install modules
# The Install-Module is similar to pip or npm, pulls from Powershell Gallery
Install-Module dbaTools
Import-Module dbaTools

$query = "SELECT * FROM dbo.sometable"
$queryParams = @{
    SqlInstance = 'testInstance'
    Database    = 'testDatabase'
    Query       = $query
}
Invoke-DbaQuery @queryParams

# You can get specific functions from a module
Import-Module -Function Invoke-DbaQuery


# Powershell modules are just ordinary Posh files. You
# can write your own, and import them. The name of the
# module is the same as the name of the file.

# You can find out which functions and attributes
# are defined in a module.
Get-Command -module dbaTools
Get-Help dbaTools -Full

/pre>

####################################################
## 6. Classes
####################################################

# We use the "class" statement to create a class
class Instrument {
    [string]$Type
    [string]$Family
}

$instrument = [Instrument]::new()
$instrument.Type = "String Instrument"
$instrument.Family = "Plucked String"

$instrument

<# Output:
Type              Family        
----              ------        
String Instrument Plucked String
#>

/pre>

####################################################
## 6.1 Inheritance
####################################################

# Inheritance allows new child classes to be defined that inherit 
# methods and variables from their parent class.

class Guitar : Instrument
{
    [string]$Brand
    [string]$SubType
    [string]$ModelType
    [string]$ModelNumber
}

$myGuitar = [Guitar]::new()
$myGuitar.Brand       = "Taylor"
$myGuitar.SubType     = "Acoustic"
$myGuitar.ModelType   = "Presentation"
$myGuitar.ModelNumber = "PS14ce Blackwood"

$myGuitar.GetType()

<#
IsPublic IsSerial Name                                     BaseType                                               
-------- -------- ----                                     --------                                               
True     False    Guitar                                   Instrument  
#>

/pre>

####################################################
## 7. Advanced
####################################################

# The powershell pipeline allows things like High-Order Functions.

# Group-Object is a handy cmdlet that does incredible things.
# It works much like a GROUP BY in SQL.

<#
 The following will get all the running processes,
 group them by Name,
 and tell us how many instances of each process we have running.
 Tip: Chrome and svcHost are usually big numbers in this regard.
#>
Get-Process | Foreach-Object ProcessName | Group-Object

# Useful pipeline examples are iteration and filtering.
1..10 | ForEach-Object { "Loop number $PSITEM" }
1..10 | Where-Object { $PSITEM -gt 5 } | ConvertTo-Json

# A notable pitfall of the pipeline is it's performance when
# compared with other options.
# Additionally, raw bytes are not passed through the pipeline,
# so passing an image causes some issues.
# See more on that in the link at the bottom.

<#
 Asynchronous functions exist in the form of jobs.
 Typically a procedural language,
 Powershell can operate non-blocking functions when invoked as Jobs.
#>

# This function is known to be non-optimized, and therefore slow.
$installedApps = Get-CimInstance -ClassName Win32_Product

# If we had a script, it would hang at this func for a period of time.
$scriptBlock = {Get-CimInstance -ClassName Win32_Product}
Start-Job -ScriptBlock $scriptBlock

# This will start a background job that runs the command.
# You can then obtain the status of jobs and their returned results.
$allJobs = Get-Job
$jobResponse = Get-Job | Receive-Job


# Math is built in to powershell and has many functions.
$r=2
$pi=[math]::pi
$r2=[math]::pow( $r, 2 )
$area = $pi*$r2
$area

# To see all possibilities, check the members.
[System.Math] | Get-Member -Static -MemberType All


<#
 This is a silly one:
 You may one day be asked to create a func that could take $start and $end
 and reverse anything in an array within the given range
 based on an arbitrary array without mutating the original array.
 Let's see one way to do that and introduce another data structure.
#>

$targetArray = 'a','b','c','d','e','f','g','h','i','j','k','l','m'

function Format-Range ($start, $end, $array) {
    [System.Collections.ArrayList]$firstSectionArray = @()
    [System.Collections.ArrayList]$secondSectionArray = @()
    [System.Collections.Stack]$stack = @()
    for ($index = 0; $index -lt $array.Count; $index++) {
        if ($index -lt $start) {
            $firstSectionArray.Add($array[$index]) > $null
        }
        elseif ($index -ge $start -and $index -le $end) {
            $stack.Push($array[$index])
        }
        else {
            $secondSectionArray.Add($array[$index]) > $null
        }
    }
    $finalArray = $firstSectionArray + $stack.ToArray() + $secondSectionArray
    return $finalArray
}

Format-Range 2 6 $targetArray 
# => 'a','b','g','f','e','d','c','h','i','j','k','l','m'

# The previous method works, but uses extra memory by allocating new arrays.
# It's also kind of lengthy.
# Let's see how we can do this without allocating a new array.
# This is slightly faster as well.

function Format-Range ($start, $end) {
  while ($start -lt $end)
  {
      $temp = $targetArray[$start]
      $targetArray[$start] = $targetArray[$end]
      $targetArray[$end] = $temp
      $start++
      $end--
  }
  return $targetArray
}

Format-Range 2 6 # => 'a','b','g','f','e','d','c','h','i','j','k','l','m'

# Find commands
Get-Command about_* # alias: gcm
Get-Command -Verb Add
Get-Alias ps
Get-Alias -Definition Get-Process

Get-Help ps | less # alias: help
ps | Get-Member # alias: gm

Show-Command Get-WinEvent # Display GUI to fill in the parameters

Update-Help # Run as admin

Get-ExecutionPolicy -List
Set-ExecutionPolicy AllSigned
# Execution policies include:
# - Restricted: Scripts won't run.
# - RemoteSigned: Downloaded scripts run only if signed by a trusted publisher. 
# - AllSigned: Scripts need to be signed by a trusted publisher.
# - Unrestricted: Run all scripts.
help about_Execution_Policies # for more info

# Current PowerShell version:
$PSVersionTable

# Calling external commands, executables, 
# and functions with the call operator.
# Exe paths with arguments passed or containing spaces can create issues.
C:\Program Files\dotnet\dotnet.exe
# The term 'C:\Program' is not recognized as a name of a cmdlet,
# function, script file, or executable program.
# Check the spelling of the name, or if a path was included, 
# verify that the path is correct and try again

"C:\Program Files\dotnet\dotnet.exe"
C:\Program Files\dotnet\dotnet.exe    # returns string rather than execute

&"C:\Program Files\dotnet\dotnet.exe --help"   # fail
&"C:\Program Files\dotnet\dotnet.exe" --help   # success
# Alternatively, you can use dot-sourcing here
."C:\Program Files\dotnet\dotnet.exe" --help   # success

# the call operator (&) is similar to Invoke-Expression, 
# but IEX runs in current scope.
# One usage of '&' would be to invoke a scriptblock inside of your script.
# Notice the variables are scoped
$i = 2
$scriptBlock = { $i=5; Write-Output $i }
& $scriptBlock # => 5
$i # => 2

invoke-expression ' $i=5; Write-Output $i ' # => 5
$i # => 5

# Alternatively, to preserve changes to public variables
# you can use "Dot-Sourcing". This will run in the current scope.
$x=1
&{$x=2};$x # => 1

.{$x=2};$x # => 2


# Remoting into computers is easy.
Enter-PSSession -ComputerName RemoteComputer

# Once remoted in, you can run commands as if you're local.
RemoteComputer\PS> Get-Process powershell

<#
Handles  NPM(K)    PM(K)      WS(K)     CPU(s)     Id  SI ProcessName                                             
-------  ------    -----      -----     ------     --  -- -----------                                             
   1096      44   156324     179068      29.92  11772   1 powershell                                              
    545      25    49512      49852             25348   0 powershell 
#>
RemoteComputer\PS> Exit-PSSession

<#
 Powershell is an incredible tool for Windows management and Automation.
 Let's take the following scenario:
 You have 10 servers.
 You need to check whether a service is running on all of them.
 You can RDP and log in, or PSSession to all of them, but why?
 Check out the following
#>

$serverList = @(
    'server1',
    'server2',
    'server3',
    'server4',
    'server5',
    'server6',
    'server7',
    'server8',
    'server9',
    'server10'
)

[scriptblock]$script = {
    Get-Service -DisplayName 'Task Scheduler'
}

foreach ($server in $serverList) {
    $cmdSplat = @{
        ComputerName  = $server
        JobName       = 'checkService'
        ScriptBlock   = $script
        AsJob         = $true
        ErrorAction   = 'SilentlyContinue'
    }
    Invoke-Command @cmdSplat | Out-Null
}

<#
 Here we've invoked jobs across many servers.
 We can now Receive-Job and see if they're all running.
 Now scale this up 100x as many servers :)
#>

Cheat Sheet 2

PowerShell Commands Cheat Sheet

cmdlets

Cmdlets are PowerShell’s internal commands. These cmdlets will return one or more objects to the pipeline where at the end of that pipeline, we mention some properties of the objects in the following table to see their values displayed on the screen.

PSdrives

PSdrives are the collection of entities grouped together so they can be accessed as a filesystem drive. The “PSprovider” does this grouping.

By default, a PS session can access several PSdrives including c:, env:, alias:, and HKLM:, where c: refers to the usual Windows c-drive; env: is the space of Windows environmental variables; alias: is the collection of cmdlet aliases; and HKLM is a hive in the registry.

Any PS session will enter the user’s home folder. If you want to switch from a PS session to another PSdrive and retrieve the information from that drive, consider the following commands:

Pipelines

Cmdlets uses the pipelines to pass the objects but not the character streams like Unix. The pipeline character is | (ASCII 124), followed by a command that handles the output passed through the pipeline. The pipeline consists of the following three stages.

Get-ChildItem *.txt | Where-Object length -lt 1000 | Sort-Object length

The following table highlights some of the basic pipeline commands:

Alias

Cmdlets come with several aliases. The following table highlights a few of aliases, along with their descriptions:

Operators

• Arithmetic Operators

• Operator Precedence

• Assignment Operators

• Comparison Operators

• Logical Operators

• Redirection Operator

• Type Operators

Some Other Operators

Regular Expressions

A regular expression is a pattern that is used to match text that includes literal characters, operators, and other constructs. PowerShell regular expressions are case-insensitive by default.

• Character Literals

A regular expression can be a literal character or a string.

• Character Groups

These allow you to match any number of characters one time, while [^character group] only matches characters NOT in the group.

• Character Range

A pattern can also be a range of characters. The characters can be alphabetic [A-Z], numeric [0-9], or even ASCII-based [ -~] (all printable characters).

• Numbers

The \d character class will match any decimal digit. Conversely, \D will match any non-decimal digit.

• Word Character

The \w character class will match any word character [a-zA-Z_0-9]. To match any non-word character, use \W.

• Wildcard

The period (.) is a wildcard character in regular expressions. It will match any character except a newline (\n).

• Whitespace

Whitespace is matched using the \s character class. Any non-whitespace character is matched using \S. Literal space characters ‘ ‘ can also be used.

• Escaping Characters

The backslash (\) is used to escape characters so the regular expression engine doesn’t parse them.

The following characters are reserved: []().\^$|?*+{}.

> '3.141' -match '3\.\d{2,]'
True

• Substitution in Regular Expression.

The regular expressions with the -replace operator allows you to dynamically replace text using captured text.

<input> -replace <original>, <substitute>

Flow Control

• ForEach-Object

ForEach-Object is a cmdlet that allows you to iterate through items in a pipeline, such as with PowerShell one-liners. ForEach-Object will stream the objects through the pipeline.

Although the Module parameter of Get-Command accepts multiple values that are strings, it will only accept them via pipeline input using the property name, or parameter input.

If you want to pipe two strings by value to Get-Command for use with the Module parameter, use the ForEach-Objectcmdlet:

$ComputerName = 'DC01', 'WEB01'

foreach ($Computer in $ComputerName) {
    Get-ADComputer -Identity $Computer
}

• For

A “for” loop iterates while a specified condition is true.

For example:

for ($i = 1; $i -lt 5; $i++) {

Write-Output "Sleeping for $i seconds"

Start-Sleep -Seconds $i

}

• Do

There are two different “do” loops in PowerShell. Do Until runs while the specified condition is false.

Example 1:

$number = Get-Random -Minimum 1 -Maximum 10

do {
    $guess = Read-Host -Prompt "What's your guess?"

    if ($guess -lt $number) {
        Write-Output 'Too low!'
    } elseif ($guess -gt $number) {
        Write-Output 'Too high!'
    }
}

until ($guess -eq $number)

Example 2:

$number = Get-Random -Minimum 1 -Maximum 10

do {
    $guess = Read-Host -Prompt "What's your guess?"

    if ($guess -lt $number) {
        Write-Output 'Too low!'
    } elseif ($guess -gt $number) {
        Write-Output 'Too high!'
    }
}

while ($guess -ne $number)

• While

Similar to the Do While loop, a While loop runs as long as the specified condition is true. The difference however, is that a While loop evaluates the condition at the top of the loop before any code is run. So, it doesn’t run if the condition evaluates to false.

For example:

$date = Get-Date -Date 'November 22'

while ($date.DayOfWeek -ne 'Thursday') {
    $date = $date.AddDays(1)
}

Write-Output $date

Variables

PowerShell allows you to store all types of values. For example, it can store command results and command expression elements like names, paths, and settings. Here are some of PowerShell’s different variables.

• User-created variables: These are created and maintained by the user. The variables you create at the PowerShell command line will only exist until the PowerShell window is open. When you close the PowerShell window, these variables are deleted. If you want to save a variable, you need to add it to your PowerShell profile. You can create variables and declare them with three different scopes: global, script, or local.

• Automatic variables: These variables store the state of PowerShell and are created by PowerShell. Only PowerShell can change their values as required to maintain accuracy. Users can’t change these variables’ value. For example, the $PSHOME variable will store the path to the PowerShell installation directory.
• Preference variables: These variables store user preferences for PowerShell and are created by PowerShell. These variables are populated with default values and can be changed by the users. For example, the $MaximumHistoryCount variable specifies the maximum number of entries in the session history.

To create a new variable, you need to use an assignment statement and assign a value to the variable. There is no need to declare the variable before using it. The default value of all variables is $null.

For example:

$MyVariable = 1, 2, 3

$MyVariable

Function

• Naming Your Function

Use a Pascal case name with an approved verb and a singular noun to name a function. You can get a list of approved verbs by running Get-Verb:

Get-Verb | Sort-Object -Property Verb

• Creating a Simple Function

Use a function keyword followed by the function name to create a simple function. Then, use an open and closing curly brace. The function will execute code contained within those curly braces.

For example:

function Get-Version {
    $PSVersionTable.PSVersion
}

Working with Modules

A module is a package containing PowerShell members, such as cmdlets, providers, functions, workflows, variables, and aliases. You can implement package members in a PowerShell script, a compiled DLL, or both. PowerShell automatically imports the modules the first time you run any command in an installed module. You can use the commands in a module without setting up or profile configuration.

• How to Use a Module

To use any module, you need to first install them. Then, find the command that comes with the module and use them.

• Installing a Module

If you get a module as a folder, install it before you use it on the PowerShell command line. Some modules are preinstalled. You can use the following command to create a Modules directory for the current user:

New-Item -Type Directory -Path $HOME\Documents\PowerShell\Modules

Copy the entire module folder into the Modules directory. You can use any method to copy the folder, including Windows Explorer, Cmd.exe, and PowerShell.

• Finding the Installed Modules

Run the following to find the modules installed in a default module location (not imported).

Get-Module -ListAvailable

• Finding Commands in a Module

Run the following command to find a module’s commands:

Get-Command -Module <module-name>

Get-Command -Module Microsoft.PowerShell.Archive

• Importing a Module

Run the following command with the proper module name:

Import-Module <module-name>

• Removing a Module Name

You can run the following command with the proper module name:

Remove-Module <module-name>

• View Default Module Locations

Use the following command to view default module locations:

$Env:PSModulePath

• Add a Default Module Location

You can use the following command format:

$Env:PSModulePath = $Env:PSModulePath + ";<path>"

• Add a Default Module Location on Linux or MacOS

Use the following to execute the same command as above, only with Linux or macOS:

$Env:PSModulePath += ":<path>"

Hash Tables

A hash table is a complex data structure to store data in the form of key-value pairs. We also refer to a hash table as a dictionary or associative array. To understand a hash table, consider a series of IP addresses and the respective computer names. A hash stores this data in the form of key-value pairs, where IP addresses refer to keys and computer names to their corresponding values.

The hash table syntax is as follows:@{ <name> = <value>; [<name> = <value> ] …}

An ordered dictionary’s syntax is as follows:[ordered]@{ <name> = <value>; [<name> = <value> ] …}

• Creating Hash Tables

If you want to create a hash table, follow these steps:

• Start the hash table with an at sign (@) and enclose it in curly braces ({}).
• A hash table should contain at least one key-value pair, and hence, enter the data after creating a hash table.
• Separate key from its value using an equal sign (=).
• Separate the key/value pairs in a hash table with a semicolon (;).
• Enclose the space between the keys in quotation marks. Values must be valid PowerShell expressions. Also, enclose strings in quotation marks, even if there are no spaces between them.
• Save a hash table as a variable to manage it efficiently.
• When assigning an ordered hash table to a variable, place the [ordered] attribute before the @ symbol. If you place it before the variable name, the command fails.

For example:

$hash = @{}

$hash = @{ Number = 1; Shape = "Square"; Color = "Blue"}

[hashtable]$hash = [ordered]@{

Number = 1; Shape = "Square"; Color = "Blue"}

$hash

• Adding and Removing Keys and Values

To add keys and values to a hash table, use the following command format:

$hash[“<key>”] = “<value>”

For example, you can add a “Time” key with a value of “Now” to the hash table with the following statement format:

$hash["Time"] = "Now"

Or

$hash.Add("Time", "Now")

Or, you can remove the key with this statement format:

$hash.Remove("Time")

Asynchronous Event Handling

These cmdlets allow you to register and unregister event subscriptions and list the existing subscriptions. You can also list pending events and handle or remove them as desired.

PowerShell eventing cmdlets

Sites

Windows PowerShell Portal

Language

Switches

Basic Syntax

Let’s start by taking a look at a basic switch statement.

Notice we don’t use the Case: keyword at all.

The default in PowerShell is to assume -eq is used between your input and typed case value. This means No Case Sensitivity and No Wild Cards:

Expression Match

We have a long-hand switch statement that lets us use whatever we want (-eq, -gt, -le, -like, straight up boolean values, etc.)

Psudo-code:Switch($value) { {<bool expression>} {<code>} {<bool expression>} {<code>} default {<code>} }

Real:

Jump Statements aren’t necessary

C# requires jump statements such as break, goto, or return. PowerShell does not!

This is one of the coolest features in PowerShell. We actually allow for continuous case- checks.

This means your switches can actually act more like a bunch of independent if statements. Notice the previous example, without any of the “break statements” and using a number that is less than 5, 10 and 15.

Loops and $_

It might be common for you to take a bunch of data, do a foreach loop through it and send each value through your switch:

However, PowerShell actually has a loop and $_ built right into your switch so we can chop off the foreach completely:

This lets us write some really concise and convenient little code blocks. The nice thing is that if our list has 1 object it still gets handled fine, and if it’s an empty collection it will just skip the whole switch!

This, however, can lead to some confusion if you try to use “break” since our loop is also the whole switch statement:

view rawLoopSwitchSample3.ps1 hosted with ❤ by GitHub

Uh-oh, not good.

We also have “continue” in PowerShell and this will stop our current iteration of our loop (or switch) so we can use the looping feature and make it like a bunch of elseifs:

Shortcuts

In addition to the looping, we provide you a few other handy short cuts.

If you just wanted a basic equality switch, but would want to use -ceq (case sensitivity), -like (wild cards), or -match (regex) we let you do that without writing an expression match via some parameters.

Notice, weirdly, the parameters must come between the word “switch” and the parenthesis, they won’t work at the end of the parenthesis.

CommandLets

• Get-Alias
• New-Alias
• Set-Alias
• Export-Alias
• Import-Alias 

Function

To see the definition of mkdir use

Get-Content Function:\mkdir

Introduction

Using Docker is an effortless way to launch and run an application/server software without annoying installation hassles: Just run the image and you’re done.

Even if it’s quite an uncomplicated way of looking at it, in many cases it works just like that.

So, let’s start with using Microsoft SQL Server as a database backend. We will use a docker image from Microsoft. Look here to find out more.

docker	run                                       \
			--name mssql-server       \
			--memory 4294967296       \	
			-e "ACCEPT_EULA=Y"        \
			-e "SA_PASSWORD=secret"   \
			-p 1433:1433              \
			mcr.microsoft.com/mssql/server:2019-latestles

FAQ

Error: program requires a machine with at least 2000 megabytes of memory

Start the docker container as described on the Docker Hub Page: How to use this Image

❯ docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=secret" -p 1433:1433 mcr.microsoft.com/mssql/server:2022-latest

Depending on how your docker environment is configured, this could bring up an error:

SQL Server 2019 will run as non-root by default.
This container is running as user mssql.
To learn more visit https://go.microsoft.com/fwlink/?linkid=2099216.
sqlservr: This program requires a machine with at least 2000 megabytes of memory.
/opt/mssql/bin/sqlservr: This program requires a machine with at least 2000 megabytes of memory.

As the error message states, the MS SQL server needs at least 2g of RAM. So, you must assign your Docker VMs more memory. This is configured in the Docker Dashboard.

Hint: Docker has two ways of running containers:

• using Windows Container
• using WSL (Windows Subsystem for Linux)

You can change the way with the context menu of the docker symbol in the task bar:

With Linux Containers (using WSL as backend), you must configure the containers via a file .wslconfig.

This file is in the folder defined by the environment variable %USERPROFILE%, which is normally C:\Users\<username>

To open the file, run the command:

Edit the content and change the memory setting

[wsl2]
memory=3GB

Restart WSL with the new settings.

❯ wsl --shutdown

Start Container again, now everything should work

❯ docker run -e "ACCEPT_EULA=Y" -e "SA_PASSWORD=secret" -p 1433:1433 mcr.microsoft.com/mssql/server:2022-latest

Introduction

Working with different software (samples, compilers, demos) always requires an adequate environment.

Because i don’t want to pollute my normal environment (my running PC), i decided to use a virtual environment with Docker.

Luckily, VS Code supports this by using remote containers and working fully within these containers.

The Files

.devcontainer\devcontainer.json

{
	"name": "Prolog Environment",

	"dockerComposeFile": [
		"docker-compose.yml"
	],

	"service": "app",
	"workspaceFolder": "/workspace",

	"settings": {},
	"extensions": []
}

.devcontainer\docker-compose.yml

version: '3.8'
services:
  app:
    
    build:
        context: .
        dockerfile: Dockerfile

    container_name: pws_prolog

    volumes:
        - ../workspace:/workspace:cached

    # Overrides default command so things don't shut down after the process ends.
    command: /bin/sh -c "while sleep 1000; do :; done"
 

.devcontainer\Dockerfile

#------------------------------------------------------------------------------
# STAGE 1:
#------------------------------------------------------------------------------
FROM ubuntu:latest as base_nodejs

# Configure Timezone
ENV TZ 'Europe/Berlin'

RUN echo $TZ > /etc/timezone 

RUN    apt-get update \
    && apt-get install -y tzdata \
    && rm /etc/localtime \
    && ln -snf /usr/share/zoneinfo/$TZ /etc/localtime \
    && dpkg-reconfigure -f noninteractive tzdata \
    && apt-get clean

#
RUN apt-get install --yes build-essential curl sudo git vim

# Create user
RUN    groupadd work -g 1000 \
    && adduser user --uid 1000 --gid 1000 --home /workspace --disabled-password --gecos User

# Setup sudo
RUN echo '%work        ALL=(ALL)       NOPASSWD: ALL' >/etc/sudoers.d/work

# Install Prolog
RUN  apt-get -y install swi-prolog

#
USER user

VOLUME [ "/workspace" ]
WORKDIR /workspace

CMD ["/bin/bash"]

The Explanation

Related CommandLets

• Get-Alias
• New-Alias
• Set-Alias
• Export-Alias
• Import-Alias 

Display Aliases

Show Aliases

Get-Alias

Show Aliases for a Command

Get-Alias -Definition Get-ChildItem

Export the entire list to a spreadsheet (a CSV file) by using the Export-Alias:

Export-Alias -Path "Alias.csv"

Show only build-in aliases (with property read-only)

Get-Alias | Where-Object {$_.Options -Match "ReadOnly"}

Create Alias

New-Alias -Name D -Value Get-ChildItem -Description "A shortcut to the Get-ChildItem cmdlet"

Create a shortcut ‘c’ for Visual Studio Code ‘code’

Set-Alias -Name c -Value code  

Create more complex aliases using functions

function Start-TheDay {
    start chrome;
    start firefox;
    start code;
    start slack;
}

Set-Alias -Name am -Value Start-TheDay  

Customize prompt

Microsoft Powershell Core – About Prompts

function Prompt(){
   $W = Split-Path -leaf -path (Get-Location)
   $prompt = Write-Prompt "$($env:UserName)@$($env:ComputerName):" -ForegroundColor Green
   $prompt += Write-Prompt $W -ForegroundColor DarkCyan
   $prompt += Write-Prompt '>'
   
   return ' '
}

Get code that sets the prompt

(Get-Command Prompt).ScriptBlock

Samples

function prompt {"PS [$env:COMPUTERNAME]> "}

function prompt {"$(Get-Date)> "}

function prompt {
  $identity = [Security.Principal.WindowsIdentity]::GetCurrent()
  $principal = [Security.Principal.WindowsPrincipal] $identity
  $adminRole = [Security.Principal.WindowsBuiltInRole]::Administrator

  $(if (Test-Path variable:/PSDebugContext) { '[DBG]: ' }
    elseif($principal.IsInRole($adminRole)) { "[ADMIN]: " }
    else { '' }
  ) + 'PS ' + $(Get-Location) +
    $(if ($NestedPromptLevel -ge 1) { '>>' }) + '> '
}

function prompt {
   # The at sign creates an array in case only one history item exists.
   $history = @(Get-History)
   if($history.Count -gt 0)
   {
      $lastItem = $history[$history.Count - 1]
      $lastId = $lastItem.Id
   }

   $nextCommand = $lastId + 1
   $currentDirectory = Get-Location
   "PS: $nextCommand $currentDirectory >"
}

function prompt {
    $color = Get-Random -Min 1 -Max 16
    Write-Host ("PS " + $(Get-Location) +">") -NoNewLine `
     -ForegroundColor $Color
    return " "
}

function Prompt
{
     # Admin ?
     if( (
        New-Object Security.Principal.WindowsPrincipal (
            [Security.Principal.WindowsIdentity]::GetCurrent())
        ).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator))
    {
        # Admin-mark in WindowTitle
        $Host.UI.RawUI.WindowTitle = "[Admin] " + $Host.UI.RawUI.WindowTitlep
        # Admin-mark on prompt
        Write-Host "[" -nonewline -foregroundcolor DarkGray
        Write-Host "Admin" -nonewline -foregroundcolor Red
        Write-Host "] " -nonewline -foregroundcolor DarkGray
    }   
    Write-Host "[" -NoNewline
    Write-Host (Get-Date -Format "HH:mm:ss") -ForegroundColor Gray -NoNewline
    Write-Host "] [" -NoNewline    
    Write-Host "$(((H)[-1].EndExecutionTime - (H)[-1].StartExecutionTime).Milliseconds) ms" -NoNewline -ForegroundColor Gray
    Write-Host "]" -NoNewline
    if(Get-Module Posh-git) {Write-VcsStatus; Write-host ''}
    Write-Host "$($executionContext.SessionState.Path.CurrentLocation.ProviderPath)" -NoNewline
    "> "
}

Docker Aliases

drm

Removes all stopped containers:

function Remove-StoppedContainers {  
    docker container rm $(docker container ls -q)
}
Set-Alias drm  Remove-StoppedContainers  

drmf

Removes all containers, whether they’re running or not:

function Remove-AllContainers {  
    docker container rm -f $(docker container ls -aq)
}
Set-Alias drmf  Remove-AllContainers  

Use with caution

dip

Gets the container’s IP address – pass it a container name or part of the container ID, e.g. dip 02a or dip dbserver:

function Get-ContainerIPAddress {  
    param (
        [string] $id
    )
    & docker inspect --format '{{ .NetworkSettings.Networks.nat.IPAddress }}' $id
}
Set-Alias dip  Get-ContainerIPAddress  

d2h

Adds a container’s IP address to the host’s hosts file, so you can refer to containers by their name on your Docker host, in the same way that containers reach each other by name.

Example – I have a web app which uses a SQL database. In dev and test environments I’ll be running SQL Server in a container for the database. The container is called petshop-db and all the connection strings in the web configuration use petshop-db as the database server name. If I want to run the web app locally, but still use a container for the database I just start the container and run d2h petshop-db. Now my web app uses the container IP from the hosts file, and I can run the whole stack with docker-compose up without changing config.

function Add-ContainerIpToHosts {  
    param (
        [string] $name
    )
    $ip = docker inspect --format '{{ .NetworkSettings.Networks.nat.IPAddress }}' $name
    $newEntry = "$ip  $name  #added by d2h# `r`n"
    $path = 'C:WindowsSystem32driversetchosts'
    $newEntry + (Get-Content $path -Raw) | Set-Content $path
}
Set-Alias d2h  Add-ContainerIpToHosts  

Network Aliases

List Jobs for Port

function List-Jobs-Using-Port {  
    param (
        [string] $port
    )

    Get-Process -Id (Get-NetTCPConnection -LocalPort $port).OwningProcess
}

Top Ten Aliases

Guy’s Top Ten Aliases

1. Cd: Set-Location
2. Cls: Clear-Host
3. Del: Remove-Item
4. Diff: Compare-Object
5. Dir: Get-ChildItem
6. Kill: Stop-Process
7. Echo: Write-Output
8. Sort: Sort-Object
9. Sleep: Start-Sleep
10. Type: Get-Content

List of Aliases

More to read

https://stackify.com/powershell-commands-every-developer-should-know/

References and Copyright

Aliases and Prompts

https://gist.github.com/sixeyed/c3ae1fd8033b8208ad29458a56856e05

Scripts

Parameter in a Powershell Script

param (
    [Parameter(Mandatory=$true)]  [string] $folder = "",
    [Parameter(Mandatory=$false)] [string] $type,
    [Parameter(Mandatory=$false)] [switch] $migrate,
    [Parameter(Mandatory=$false)] [switch] $help
)

Call the Script

.\script.ps1 foldername
.\script.ps1 foldername -type=folder

.\script.ps1 foldername -type=folder -migrate

Parameter Debug and Verbose

This parameter could not be defined in a script, because they are already present.

param (
    [Parameter(Mandatory=$false)] [switch] $debug
)

.\using_parameter.ps1 : Ein Parameter mit dem Namen "Debug" wurde mehrfach für den Befehl definiert.
In Zeile:1 Zeichen:1
+ .\using_parameter.ps1
+ ~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : MetadataError: (:) [], MetadataException
    + FullyQualifiedErrorId : ParameterNameAlreadyExistsForCommand

To access their values, use

param (
    [Parameter(Mandatory=$false)] [switch] $help
)

$debug   = $PSBoundParameters.ContainsKey('Debug')
$verbose = $PSBoundParameters.ContainsKey('Verbose')

Write-Host "help    = $help"
Write-Host "debug   = $debug"
Write-Host "verbose = $verbose"

> .\using_parameter.ps1  -debug -help
help    = True
debug   = True
verbose = False
> .\using_parameter.ps1  -debug 
help    = False
debug   = True
verbose = False
> .\using_parameter.ps1  -debug -verbose
help    = False
debug   = True
verbose = True

String

Converting String to TitleCase

function toTitleCase($string) {
    return $string.substring(0,1).toupper()+$string.substring(1).tolower()

}

Filesystem

List of Files in a Folder

(ls -r *.txt).fullname

Get-ChildItem -recurse -Filter .editorconfig -path . | % { $_.fullname }

dir -Path . -Filter ProfileInformationController* -Recurse | %{$_.FullName}

Counting Files

Using  Scripting.FileSystemObject

$objFSO = New-Object -com  Scripting.FileSystemObject
$objFSO.GetFolder($folder).Files.Count

Find a Folders within a Folder (not recursive)

(Get-ChildItem --Attributes Directory).Name

Run Command for each Folder

(Get-ChildItem  -Attributes Directory).Name | % { <COMMAND> $_ }

With Enumerator

[IO.Directory]::EnumerateFiles($folder) | ForEach-Object {
    Write-Host $_
}

Find all folders with Pattern

Get-ChildItem -recurse -depth 2 -directory -path ..\packages_flutter | `
Where-Object { $_.FullName -match 'example' }                        | `
% { $_.FullName .split('\')[-2] } | `
% { junction $_  ..\packages_flutter\packages\$_\example }

Delete files with pattern

Get-ChildItem *.code -recurse | foreach { Remove-Item -Path $_.FullName }

Get-ChildItem -Path C:Temp -Include *.* -File -Recurse | foreach { $_.Delete()}

Files

Filename and Extension of File with Split-Path

Filename

Split-Path -Path <PATH> -Leaf

Folder

Split-Path -Path <PATH>

Extension

Split-Path -Path <PATH> -Extension

Create File

New-Item new.txt -type file

Loop through entries of a textfile

Get-Content list-of-folders | Where-Object {$_ -NotMatch "#.*" } | ForEach-Object { 
    .\check_folder.ps1$_
    # Write-Host "Weiter -->" -NoNewLine
    # $key = $Host.UI.RawUI.ReadKey()
}

Loop through results from Select-String

Here is an example that greps for a string and uses the results in a loop to determine if some action should be taken

$pattern = "powershell"
$files = Select-String -Path "d:\script\*.txt" -Pattern $pattern
foreach ($file in $files) {
   $filename=$file.Filename
   $item = get-item $file.Path
    "File '{0}' matches the pattern '{1}'" -f $item.FullName, $pattern
    "It was last modified on {0}" -f $item.LastWriteTime
 
   $response = Read-Host -Prompt "Set the archive bit on this file?" 
   If ($response -eq 'Y') {
      $item.attributes="Archive"
   }
}

Check if a file exist

Test-Path $PROFILE

Searching in Files

Get-ChildItem -Recurse | Select-String "dummy" -List | Select Path

Get-ChildItem -Recurse *.sql | Select-String "create .*_tab_" | Select-Object -Unique Path

Select-String -path *.txt -pattern PowerShell

Select-String -path *.txt -pattern PowerShell -notmatch

Parsing Files

Get first line of output

$eventResult.Split([Environment]::NewLine) | Select -First 1

Web

Download Web-Page

Invoke-WebRequest -Uri <link>

List all Links

$response = Invoke-WebRequest -Uri <link>
$response.links | Select -Expand href

List all Links with filtering href by RegEx

$response.Links | Where-Object {$_.href -like "*videos*" } | ForEach-Object { $_.href }

List all Links with filtering class name by RegEx

$response.Links | Where-Object {$_.class -eq "page-numbers"} | Format-List innerText, href

Download and Install Visual Studio Code in portable Mode

$FOLDER=Get-Date -Format "yyyy-MM-dd-HH-mm"

Write-Host "Create link for folder $FOLDER"


# Download
# https://code.visualstudio.com/sha/download?build=stable&os=win32-x64-archive
# https://code.visualstudio.com/sha/download?build=insider&os=win32-x64-archive

$LINK="https://code.visualstudio.com/sha/download?build=insider&os=win32-x64-archive"
$FILE="vscode-insider.zip"

if (Test-Path "$FILE") {
	Remove-Item "$FILE"
}

Invoke-WebRequest "$LINK" -OutFile "$FILE"

Expand-Archive "$FILE" "$FOLDER"

if (Test-Path $FOLDER\data)
{
	Remove-Item $FOLDER\data
}


if (Test-Path code) { Remove-Item code }

# Using junction from SysInternalsSuite to create symlinks

junction code $FOLDER
junction code\data data

Environment

Show env variables

gci env:* | Sort-Object Name

Show env variables with name pattern

gci env: | Where name -like '*HOME

Processes

List Processes and Path

Get-Process | Select-Object Path

Show processes using a specific port

Get-Process -Id (Get-NetTCPConnection -LocalPort YourPortNumberHere).OwningProcess

Network

Pipeline

Parse out from command

$REPOSITORY=<URL of Repository>
git branch -r | ForEach-Object { Write-Output "git clone -b $_ $REPOSITORY $_" } | Out-File -FilePath .clone-all-branches

Permissions

Show current policy

Get-ExecutionPolicy

Allow custom scripts to execute

Set-ExecutionPolicy -Scope CurrentUser unrestricted

Security

Self-Sign a script

Step 1: Create your code signing certificate

New-SelfSignedCertificate -DnsName user@via-internet.de `
                          -CertStoreLocation Cert:\currentuser\my  `
                          -Subject "CN=Local Code Signing"  `
                          -KeyAlgorithm RSA  `
                          -KeyLength 2048  `
                          -Provider "Microsoft Enhanced RSA and AES Cryptographic Provider"  `
                          -KeyExportPolicy Exportable  `
                          -KeyUsage DigitalSignature  `
                          -Type CodeSigningCert

Step 2: Open the Certificate Manager for Current User

certmgr /s my

Step 3: Copy the new certificate to the appropriate cert stores

From Personal folder into Trusted Root Certification Authorities and into Trusted Publishers stores.

German: Von Eigene Zertifikate nach Vertrauenswürdige Stammzertifizierungsstellen und Vertrauenswürdige Herausgeber

Step 4: Sign your PowerShell script with the new cert

$CERT=@(Get-ChildItem cert:\CurrentUser\My -CodeSigning)[1]
Set-AuthenticodeSignature .\HelloWorld.ps1 $CERT

Or

❯ Set-AuthenticodeSignature -FilePath .\HelloWorld.ps1 -Certificate (Get-ChildItem -Path Cert:CurrentUserMy -CodeSigningCert)

Final Check

❯ Get-AuthenticodeSignature .\HelloWorld.ps1

Github

Download Repositories

gh repo list <github username> --limit 1000 | % { $_.split("`t")[0] }| Select-String -NoEmphasis <pattern> | % { git clone --depth 1 https://github.com/$_ }

Profiles

Different PowerShell profiles

Show Path for all profiles

$PROFILE | Format-List * -Force

Create a new profile

New-Item $PROFILE.CurrentUserAllHosts -ItemType file -Force

Customizing

Theming

https://ohmyposh.dev/

Install Posh-Git and Oh-My-Posh.

Install-Module posh-git   -Scope CurrentUser
Install-Module oh-my-posh -Scope CurrentUser

Install-Module -Name PSReadLine -AllowPrerelease -Scope CurrentUser -Force -SkipPublisherCheck

Then run “notepad $PROFILE” and add these lines to the end:

Import-Module posh-git
Import-Module oh-my-posh

Set-Theme Paradox

Set a custom theme

Import-Module posh-git
Import-Module oh-my-posh
Set-Theme Paradox

Show current theme settings

$ThemeSettings

$ThemeSettings.CurrentThemeLocation

Customize Prompt

Show current Path

function prompt
{
    "PS " + $(get-location) + "> "
}

Randor Color

function prompt
{
    $random = new-object random
    $color=[System.ConsoleColor]$random.next(1,16)
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor $color
    return " "
}

Display current time at the end of prompt line (this will mess up you console buffer)

function prompt
{
    $oldposition = $host.ui.rawui.CursorPosition
    $Endline = $oldposition
    $Endline.X+=60
    $host.ui.rawui.CursorPosition = $Endline
    Write-Host $(get-date).Tostring("yyyy-MM-dd HH:mm:ss")
    $host.ui.rawui.CursorPosition = $oldposition
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return " "
}

Show current user, host, current line number

$global:CurrentUser = [System.Security.Principal.WindowsIdentity]::GetCurrent()
function prompt
{
    $host.ui.rawui.WindowTitle = $CurrentUser.Name + " " + $Host.Name + " " + $Host.Version + " Line: " + $host.UI.RawUI.CursorPosition.Y
    Write-Host ("PS " + $(get-location) +">") -nonewline -foregroundcolor Magenta
    return " "
}

Weitere Anpassungsmöglichkeiten

https://www.norlunn.net/2019/10/07/powershell-customize-the-prompt/

Security

❯ New-SelfSignedCertificate -DnsName user@via-internet.de -CertStoreLocation Cert:CurrentUserMy -Type CodeSigning

   PSParentPath: Microsoft.PowerShell.SecurityCertificate::CurrentUserMy

Thumbprint                                Subject              EnhancedKeyUsageList
----------                                -------              --------------------
4AED871E6DB5FF3E85EB1625C5369DBDB3E120FD  CN=user@via-interne… Codesignatur

❯ Set-AuthenticodeSignature -FilePath demo.ps1 -Certificate (Get-ChildItem -Path Cert:CurrentUserMy -CodeSigningCert)

    Directory: D:TMP

SignerCertificate                         Status                               StatusMessage                     Path
-----------------                         ------                               -------------                     ----
4AED871E6DB5FF3E85EB1625C5369DBDB3E120FD  Valid                                Signature verified.               demo.ps1

Final Check

❯ Get-AuthenticodeSignature .demo.ps1

    Directory: D:CLOUDEnvironmentsKeycloakKeycloak12.0.1bin

SignerCertificate                         Status                                StatusMessage                    Path
-----------------                         ------                                -------------                    ---
4AED871E6DB5FF3E85EB1625C5369DBDB3E120FD  Valid                                 Signature verified.              demo.ps1

From Bash to Powershell

• https://mathieubuisson.github.io/powershell-linux-bash/

Alias for WHICH command

❯ (get-command FILE.EXE).Path

❯ Set-Alias where Get-Command
❯ where FILE.EXE

Snippets

Formatting

0..31 | ForEach-Object { 
    "{0,6}`t{1,6}`t{2,5}`t0x{0:X4}" -f $_,[Convert]::ToString($_,2), [Convert]::ToString($_,8) 
}

Select a Service By Name (Partial Match)

> Get-Service | Select-Object -ExpandProperty Name | Select-String -pattern 'ws'

CURL For Powershell

> (Invoke-WebRequest www.google.com).Content

List Environment Variables

> gci env: | sort name

Get PS Version

> $PSVersionTable

List Installed Programs

> Get-WmiObject -Class Win32_Product

Colored Header in Output

$prefix ="$prefix                   ".Substring(0,6)
$title  ="$title                    ".Substring(0,15)

$line = "$prefix ${title}: ${line}"
$fill = " " * ([Console]::WindowWidth - $line.length)
Write-Host "${line}${fill}"  -ForegroundColor White -BackgroundColor Blue -NoNewline