Learning PowerShell with Michael.

At the present, I am refining my PowerShell usage, updating my scripts to make the code more readable and slowly learning new methods to do things easier, and faster. I’ve been on several forums relating to PowerShell and am quite active (you may have found this blog from there?), and thought I’d make my own post.

Whilst I’ll attempt to be as thorough as possible (we all know I do not vet my own documents), this shall not be an all-encompassing guide/post on PowerShell. The post will briefly cover:

  1. What is Windows Management Framework 5.0?
  2. IDE(s) and their benefits
  3. Using Variables
  4. Using Functions

So, let’s get into it.

What is Windows Management Framework 5.0?

The technical answer is:

Windows Management Framework (WMF) is the delivery mechanism that provides a consistent management interface across the various flavors of Windows and Windows Server.

Source

In easier terminology, it is a distinct sub-set of Windows tools designed for automation, maintaining and auditing Windows PC(s), and primarily, Windows Servers.

Think of WMF as a toolbox, that houses tools:

In Windows, .NET Framework and PowerShell are implemented through the Enable/Disable Features option.

Of course, you should be able to just use DISM to enable the feature as well:

Dism /online /enable-feature /featurename:NetFx3 /All /Source:F:\sources\sxs /LimitAccess
  •  Where F:\sources\sxs is your installation directory SXS folder.

Note the following availability:

Operating System Version WMF 5.1 WMF 5.0 WMF 4.0 WMF 3.0 WMF 2.0
Windows Server 2016 Ships in-box
Windows 10 Ships in-box Ships in-box
Windows Server 2012 R2 Yes Yes Ships in-box
Windows 8.1 Yes Yes Ships in-box
Windows Server 2012 Yes Yes Yes Ships in-box
Windows 8 Ships in-box

IDE(s) and their benefits

Integrated Development Environments, or “IDE”, are different to the Integrated Scripting Environment, “ISE”, slightly. For example, the following quote depicts IDE:

An IDE normally consists of a source code editorbuild automation tools and a debugger. Most modern IDEs have intelligent code completion. Some IDEs, such as NetBeans and Eclipse, contain a compilerinterpreter, or both.

ISE is rather limited, as:

  • It is designed for PowerShell only (as far as I am aware);
  • There is no real debugger, just console output and;
  • It was designed for Microsofts Operating System Only (Can be run on Linux and OSX though)

Whilst I do not dislike the ISE for PowerShell, it’s not one I would suggest you use. Sure, it has all the cmdlets housed in a neat menu, depicting what category they fall under, but that’s it.

Personally, I would recommend Microsoft other IDE tool, Visual Studio. The same syntax highlighting, and autocomplete functions are readily available, it supports multiple languages, and has a community list of add-ons.

to0c68u

VS Code Syntax Highlighting

Benefits of using Visual Studio Code over ISE:

  • If you decide PowerShell is not for you, change your palette language!
  • Heaps of useful add-ons;
  • Open Source;
  • Fantastic Syntax Highlighting and auto-complete and;
  • Because it’s just better.

 

Using Variables

Variables are the second most powerful “function” (no pun(s) intended) in PowerShell, in my opinion. A variable is a string of data defined in a script that can be referenced later, to make the code shorter, cleaner and more consistent.

A variable can take a complex command, and make it easier to reference down the script. In the following example, I have set 4 variables for commands I wish to use:

$Name = "$env:USERNAME"
$PC = "hostname" 
$Date= "(Get-Date).ToString('dd-MM-yyyy')"
$Time = Get-Date -Format HH-mm-ss

To set a variable, you use the following Syntax:

$Name of the variable = "action to perform"

Which can be translated:

$YourName = Read-Host "What is your name"
Greetings, "$YourName"

Always remember to call a variable using the “$” symbol, and keep it in a quote for clean code.

Variables allow you to replicate a complex command easily, multiple times throughout a script. Editing the function of the variable is reflected each time the script calls the variable. Without variables, code would be a lot messier and could be much harder to debug – a wrong comma in a line incorrectly copied could break the entire script.

Some useful examples are:

Learning how to implement variables allows for scripts that are:

  • Smaller in size;
  • Smaller in code;
  • Generally more robust;
  • Easier to debug;
  • Generally easier to read (if shared)

Using Functions

Functions are perhaps the most useful feature of PowerShell. PowerShell functions, similar to variables, allow you to perform complex command(s), and reference them by a function. The syntax being:

function "name"() {
command 1
command 2
etc
}
name()
  • “name”() is the name of set function;
  • {} are the open and close of the function, placed at beginning and end and;
  • name() actually executes the function; it does not need to be called straight after the function.

Functions support variables that can be predefined in the PowerShell script. In the following example, the function “shutdownalldomainpcs()” is using 4 variables to execute a command:

$H = Read-Host "What is the IP Address of your Domain Controller?" 
$nH = "\\*" 
$-u = Read-Host "What's your domain admin username?" 
$-p = Read-Host "Enter Password"-AsSecureString 
$command = "psexec "$nH" "$-u" "$-p" shutdown -f -r -t 0" 


function shutdownalldomainpcs(){ 
psexec "-H" "$-u" "$-p" "command" 
}
shutdownalldomainpcs

Yes, there may be syntax errors or the command might not even work, I am simply demonstrating. Should totally try with domain admin rights however.

You can read a little more on variables and functions from Microsoft here:

function test ($x, $y) 
 {
 $x * $y 
 }

Enough functions and variables, let’s nest functions! Yeah, you heard me. Functions calling functions!

A simple example:

function 1() {
Write 1
}

function 2() {
Write 2
}

function 3() {
1()
2()
}

3()

The third function executes Function 1 and 2. Handy little trick to allow you to perform multiple steps.

In the following example, I set multiple variables, and then use a “IF” switch to see if a directory is made, and write data to it:

test

Again pure example, code could not work 😉

Some useful links if you are interested:

 

Want to edit this post? Want to post your own content?

I am hoping for some additional writers on this blog. If you want to contribute, please use the comment function, and I will be in touch.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s