diff options
Diffstat (limited to 'powershell.html.markdown')
| -rw-r--r-- | powershell.html.markdown | 224 |
1 files changed, 117 insertions, 107 deletions
diff --git a/powershell.html.markdown b/powershell.html.markdown index 41f5b5ae..42a8338f 100644 --- a/powershell.html.markdown +++ b/powershell.html.markdown @@ -43,9 +43,10 @@ Powershell as a Language: 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 +# 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 @@ -55,10 +56,10 @@ Powershell as a Language: # Modulo operation 7 % 3 # => 1 -# Exponentiation requires longform or the built-in [Math] class +# Exponentiation requires longform or the built-in [Math] class. [Math]::Pow(2,3) # => 8 -# Enforce order of operations with parentheses +# Enforce order of operations with parentheses. 1 + 3 * 2 # => 7 (1 + 3) * 2 # => 8 @@ -75,20 +76,20 @@ $False # => False $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 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 +# 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 them to booleans for evaluation +# 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 @@ -115,10 +116,10 @@ $False - 5 # => -5 1 -lt 2 -and 2 -lt 3 # => True 2 -lt 3 -and 3 -lt 2 # => False -# (-is vs. -eq) -is checks if two objects are the same type +# (-is vs. -eq) -is checks if two objects are the same type. # -eq checks if the objects have the same values. # Note: we called '[Math]' from .NET previously without the preceeding -# namespaces. We can do the same with [Collections.ArrayList] if preferred +# namespaces. We can do the same with [Collections.ArrayList] if preferred. [System.Collections.ArrayList]$a = @() # Point a at a new list $a = (1,2,3,4) $b = $a # => Point b at what a is pointing to @@ -142,12 +143,15 @@ $b -is $a.GetType() # => False, a and b types not equal # 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 +# 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." +"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 @@ -166,7 +170,7 @@ $null # => None # $null, 0, and empty strings and arrays all evaluate to False. # All other values are True -function test ($value) { +function Test-Value ($value) { if ($value) { Write-Output 'True' } @@ -175,12 +179,13 @@ function test ($value) { } } -test ($null) # => False -test (0) # => False -test ("") # => False -test [] # => True *[] calls .NET classes; creates '[]' string when passed to func -test ({}) # => True -test @() # => 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 #################################################### @@ -205,9 +210,9 @@ $someVariable # => 5 0 ? 'yes' : 'no' # => no -# The default array object in Powershell is an fixed length array +# The default array object in Powershell is an fixed length array. $defaultArray = "thing","thing2","thing3" -# you can add objects with '+=', but cannot remove objects +# 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 @@ -217,12 +222,12 @@ $defaultArray.Add("thing4") # => Exception "Collection was of a fixed size." # You can start with a prefilled ArrayList [System.Collections.ArrayList]$otherArray = @(4, 5, 6) -# Add stuff to the end of a list with add (Note: it produces output, so 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 the end with index of count of objects-1 as arrays are indexed starting 0 +# 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. @@ -265,24 +270,24 @@ $array.AddRange($otherArray) # Now $array is [1, 2, 3, 4, 5, 6] # Check for existence in a array with "in" 1 -in $array # => True -# Examine the length with "Count" (Note: Length method on arrayList = each items length) +# 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 +# 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 +# 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] # => $null +$tuple[0..2] # => $null 2 -in $tuple # => False -# Hashtables store mappings from keys to values, similar to Dictionaries +# Hashtables store mappings from keys to values, similar to Dictionaries. $emptyHash = @{} # Here is a prefilled dictionary $filledHash = @{"one"= 1 @@ -294,14 +299,14 @@ $filledHash["one"] # => 1 # Get all keys as an iterable with ".Keys". # items maintain the order at which they are inserted into the dictionary. -$filledHash.keys # => ["one", "two", "three"] +$filledHash.Keys # => ["one", "two", "three"] # Get all values as an iterable with ".Values". -$filledHash.values # => [1, 2, 3] +$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 +1 -in $filledHash.Values # => False # Looking up a non-existing key returns $null $filledHash["four"] # $null @@ -309,7 +314,7 @@ $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 # $filledHash["four"] is set to 4, run again and it does nothing +$filledHash["four"] = 4 # $filledHash["four"] is set to 4, running again does nothing # Remove keys from a dictionary with del $filledHash.Remove("one") # Removes the key "one" from filled dict @@ -428,8 +433,8 @@ Add-Numbers 1 2 # => 3 # Calling functions with parameters function Add-ParamNumbers { - param( [int]$FirstNumber, [int]$SecondNumber ) - $FirstNumber + $SecondNumber + param( [int]$firstNumber, [int]$secondNumber ) + $firstNumber + $secondNumber } Add-ParamNumbers -FirstNumber 1 -SecondNumber 2 # => 3 @@ -457,9 +462,9 @@ function New-Website() { [ValidateSet(3000,5000,8000)] [int]$port = 3000 ) - BEGIN { Write-Verbose 'Creating new website(s)' } + BEGIN { Write-Output 'Creating new website(s)' } PROCESS { Write-Output "name: $siteName, port: $port" } - END { Write-Verbose 'Website(s) created' } + END { Write-Output 'Website(s) created' } } @@ -521,8 +526,8 @@ String Instrument Plucked String ## 6.1 Inheritance #################################################### -# Inheritance allows new child classes to be defined that inherit methods and -# variables from their parent class. +# Inheritance allows new child classes to be defined that inherit +# methods and variables from their parent class. class Guitar : Instrument { @@ -533,9 +538,9 @@ class Guitar : Instrument } $myGuitar = [Guitar]::new() -$myGuitar.Brand = "Taylor" -$myGuitar.SubType = "Acoustic" -$myGuitar.ModelType = "Presentation" +$myGuitar.Brand = "Taylor" +$myGuitar.SubType = "Acoustic" +$myGuitar.ModelType = "Presentation" $myGuitar.ModelNumber = "PS14ce Blackwood" $myGuitar.GetType() @@ -551,67 +556,68 @@ True False Guitar Instrument ## 7. Advanced #################################################### -# The powershell pipeline allows things like High-Order Functions +# The powershell pipeline allows things like High-Order Functions. -# Group Object is a handy command that does incredible things for us -# It works much like a GROUP BY in SQL would +# 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 + 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 +# Useful pipeline examples are iteration and filtering. 1..10 | ForEach-Object { "Loop number $PSITEM" } 1..10 | Where-Object { $PSITEM -gt 5 } | ConvertTo-Json -# A noteable 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 +# 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 many non-blocking functions when invoked as Jobs + 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 commonly known to be non-optimized, and therefore slow +# 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 +# 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 +# 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 +$jobResponse = Get-Job | Receive-Job -# Math is built in to powershell and has many functions +# Math is built in to powershell and has many functions. $r=2 $pi=[math]::pi $r2=[math]::pow( $r, 2 ) -$Area = $pi*$r2 -$Area +$area = $pi*$r2 +$area -# To see all possibilities, check the members +# To see all possibilities, check the members. [System.Math] | Get-Member -Static -MemberType All + <# - This is a silly one + This is a silly one: You may one day be asked to create a func that could take $start and $end and reverse anything in an array within the given range - based on an arbitrary array without mutating the original array - Let's see one way to do that and introduce another data structure + based on an arbitrary array without mutating the original array. + Let's see one way to do that and introduce another data structure. #> -$targetArray = 'a','b','c','d','e','f','g','h','i','j','k','l','m','n' +$targetArray = 'a','b','c','d','e','f','g','h','i','j','k','l','m' function Format-Range ($start, $end) { [System.Collections.ArrayList]$firstSectionArray = @() @@ -628,16 +634,16 @@ function Format-Range ($start, $end) { $secondSectionArray.Add($targetArray[$index]) > $null } } - $returnArray = $firstSectionArray + $stack.ToArray() + $secondSectionArray - Write-Output $returnArray + $finalArray = $firstSectionArray + $stack.ToArray() + $secondSectionArray + Write-Output $finalArray } -Format-Range 2 6 # => 'a','b','g','f','e','d','c','h','i','j','k','l','m','n' +Format-Range 2 6 # => 'a','b','g','f','e','d','c','h','i','j','k','l','m' -# The previous method works, but it uses extra memory by allocating new arrays -# It's also kind of lengthy -# Let's see how we can do this without allocating a new array -# This is slightly faster as well +# The previous method works, but uses extra memory by allocating new arrays. +# It's also kind of lengthy. +# Let's see how we can do this without allocating a new array. +# This is slightly faster as well. function Format-Range ($start, $end) { while ($start -lt $end) @@ -651,7 +657,7 @@ function Format-Range ($start, $end) { return $targetArray } -Format-Range 2 6 # => 'a','b','g','f','e','d','c','h','i','j','k','l','m','n' +Format-Range 2 6 # => 'a','b','g','f','e','d','c','h','i','j','k','l','m' ``` Powershell as a Tool: @@ -688,22 +694,26 @@ $PSVersionTable ``` ```Powershell -# Calling external commands, executables, and functions with the call operator. -# Executables with arguments passed create issues +# 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 +# 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 the string rather than execute it +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. -# Standard usage of '&' would be to invoke a scriptblock inside of your script. +# 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 } @@ -714,17 +724,17 @@ 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 +# 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 +# Remoting into computers is easy. Enter-PSSession -ComputerName RemoteComputer -# Once remoted in, you can run commands as if you're local +# Once remoted in, you can run commands as if you're local. RemoteComputer\PS> Get-Process powershell <# @@ -736,10 +746,10 @@ Handles NPM(K) PM(K) WS(K) CPU(s) Id SI ProcessName 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 + 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 #> @@ -757,24 +767,24 @@ $serverList = @( 'server10' ) -[scriptblock]$Script = { +[scriptblock]$script = { Get-Service -DisplayName 'Task Scheduler' } foreach ($server in $serverList) { - $CmdSplat = @{ - ComputerName = $Server + $cmdSplat = @{ + ComputerName = $server JobName = 'checkService' - ScriptBlock = $Script + ScriptBlock = $script AsJob = $true ErrorAction = 'SilentlyContinue' } - Invoke-Command @CmdSplat | Out-Null + 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 + 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 :) #> ``` |