powershell primer
1.0.0
$example = " World " ; # Variable names start with $
$digits = 12345 # Semicolons are optional
$output = Get-Help # Variables also store the output of commands # Initialization
$example = " World " # Quotes make strings
$example = ' World ' # Single quotes make strings too
" Hello $example " # This becomes 'Hello World'
' Hello $example ' # But this stays as 'Hello $example'
# Operations
" Hello " + $example # Use '+' to join strings
$example .Substring ( 0 , 2 ) # Strings have methods. This returns 'Wo'
$example .Replace ( " l " , " " ) # And this returns 'Word'
# Comparison
$example .StartsWith ( " W " ) # Returns true
$example .Contains ( " or " ) # Returns true too
$example .EndsWith ( " ld " ) # Returns true as well # Initialization
$items = @ () # Creates an empty array
$stock = @ ( " C " , " D " , " E " ) # Creates an array with existing elements
$stock .Length # Returns 3
$stock [ 0 ] # Returns 'C'
# Operations
$items = $items + " A " # This adds 'A' to the empty array
$items += " B " # This adds 'B'
$items += $stock # Array now has 'A', 'B', 'C', 'D', 'E'
$items -contains " C " # Returns true # Initialization
$table = @ {} # Creates an empty hashtable
$table .Planet = ' Earth ' # Adds a key-value pair
$table [ ' Dog ' ] = ' Corgi ' # Also adds a key-value pair
$table = @ { # Same as everything above, but combined
Planet = ' Earth ' ; # Semicolons are needed to separate pairs here
Dog = ' Corgi ' ;
}
# Properties
$table .Keys # Returns Planet, Dog
$table .Values # Returns Earth, Corgi
$table .Count # Returns 2
$table .ContainsKey ( ' Dog ' ) # Returns true $data = Read-Host # Captures user input from console
$data = Get-Content notes.txt # Captures contents of a file
$data = cat notes.txt # This Unix-like alias also works
$data = cat " notes.txt " # Quotes around the filename works too Write-Host $data # Writes to console
echo $data # This alias also writes to console
$data >> notes.txt # Writes to a file, appending to it
$data > notes.txt # Writes to a file, overwriting it
$data | Some - Command # Pipes to a PowerShell command # The usual math operators exist
$value = ( 5 + 3 ) - 1 # Evaluates to 7
$value = ( 6 / 3 ) * 2 # Evaluates to 4
$value = 10 % 4 # Evaluates to 2 (modulo)
# Incrementing/decrementing
$value ++ # Goes up by 1
$value -- # Goes down by 1
# Operators for equality and boolean logic
$value -gt 0 # True if $value is a positive number
$value -eq 42 # True if $value is 42
! ( $value -eq 42 ) # Negation for previous statement
# Commonly used operators
-and # Logical And
-or # Logical Or
-not , ! # Negation
-eq # Equal to
-ne # Not equal to
-gt # Greater than
-lt # Less than
-ge # Greater than or equal
-le # Less than or equal # The usual if-else statements will work, but
# in this language, 'elseif' has no space in it
if ( -not $value ) {
# Executed if $value is not defined
}
elseif (( $value % 14 ) -eq 0 ) {
# Executed if $value is divisible by 14
}
else {
# Executed if no other condition matched
} # This language supports the classic for-loop
# plus the foreach-loop as a bonus
for ( $i = 0 ; $i -lt 10 ; $i ++ ) {
echo $i
}
foreach ( $item in $array ) {
echo $item
}
# Classic while-loops and do-loops also work
while ( $number -lt 10 ) {
$number ++
}
do {
$number --
} while ( $number -gt 0 ) # Declares a basic function
function Show-Message {
echo " Hello World "
}
# Call the function using its name
Show-Message
# Defines a function with arguments and a return value
function Get-Message {
param (
$Greeting ,
$Name
)
return " $Greeting $Name "
}
# Call the function with arguments
Get-Message - Greeting " Hello " - Name " World "
# Using positional arguments also works
Get-Message " Hello " " World " # Use the & operator to execute scripts
& " /Path/To/Script.ps1 "
# This would work too:
$script = " /Path/To/Script.ps1 "
& $script
# Like functions, scripts can accept arguments
& $script - Greeting " Hello " - Name " World " # This is a single line comment.
# And here is another single line comment.
<#
Here is a multi-line comment block.
Everything inside this block will
be ignored!
#>
