PowerShell/docs/learning-powerShell/powershell-beginners-guide.md

PowerShell Beginners Guide
====

If you are new to PowerShell, this document will walk you through a few examples to give you some basic ideas of PowerShell. We recommend that you open a PowerShell console/session and type along with the instructions in this document to get most out of this exercise.


Launch PowerShell Console/Session
---
First you need to launch a PowerShell session by following the [Installing PowerShell Guide](./learning-powershell.md#installing-powershell).


Getting Familiar with PowerShell Commands
---

As mentioned above PowerShell commands is designed to have Verb-Noun structure, for instance Get-Process, Set-Location, Clear-Host, etc. Let’s exercise some of the basic PowerShell commands also known as **cmdlets**.

Please note that we will use the PowerShell prompt sign **PS />** in the following examples as it shows on Linux.
It looks like **PS C:\>** on  Windows.

**1. Get-Process**: displays the processes running on your system.

By default, you will get data back similar to the following:
``` PowerShell
PS />Get-Process

Handles   NPM(K)    PM(K)     WS(K)     CPU(s)     Id    ProcessName
-------  ------     -----     -----     ------     --    -----------
    -      -          -           1      0.012     12    bash
    -      -          -          21     20.220    449    powershell
    -      -          -          11     61.630   8620    code
    -      -          -          74    403.150   1209    firefox

…
```
Only interested in the instance of firefox process that are running on your computer? Try this:
```PowerShell
PS /> Get-Process -Name firefox

Handles   NPM(K)    PM(K)     WS(K)    CPU(s)     Id   ProcessName
-------  ------     -----     -----    ------     --   -----------
    -      -          -          74   403.150   1209   firefox

```
Want to get back more than one process? Then just specify process names, separating with commas. For example,
```PowerShell
PS /> Get-Process -Name firefox, powershell
Handles   NPM(K)    PM(K)     WS(K)    CPU(s)     Id   ProcessName
-------  ------     -----     -----    ------     --   -----------
    -      -          -          74   403.150   1209   firefox
    -      -          -          21    20.220    449   powershell

```

**2. Clear-Host**: Clears the display in the command window
```PowerShell
PS /> Get-Process
PS /> Clear-Host
```
Type too much just for clearing the screen? Here is how the alias can help.

**3. Get-Alias**:  Improves the user experience by using the Cmdlet aliases

To find the available aliases, you can type below cmdlet:
```PowerShell
PS /> Get-Alias

CommandType     Name
-----------     ----
…

Alias           cd -> Set-Location
Alias           cls -> Clear-Host
Alias           copy -> Copy-Item
Alias           dir -> Get-ChildItem
Alias           gc -> Get-Content
Alias           gmo -> Get-Module
Alias           ri -> Remove-Item
Alias           type -> Get-Content
…

As you can see "cls" is an alias of Clear-Host. Now try it:

PS /> Get-Process
PS /> cls
```
**4. cd - Set-Location**: change your current working directory
```PowerShell
PS /> Set-Location /home
PS /home>
```
**5. ls or dir - Get-ChildItem**: list all items in the specified location

```PowerShell
Get all files under the current directory:

PS /> Get-ChildItem

Get all files under the current directory as well as its subdirectories:
PS /> cd $home
PS /home/jen> dir -Recurse

List all files with file extension "txt".

PS /> cd $home
PS /home/jen> dir –Path *.txt -Recurse
```

**6. New-Item**: Create a file

```PowerShell
An empty file is created if you type the following:
PS /home/jen> New-Item -Path ./test.ps1


    Directory: /home/jen


Mode                LastWriteTime         Length  Name
----                -------------         ------  ----
-a----         7/7/2016   7:17 PM              0  test.ps1
```
You can use the **-value** parameter to add some data to your file. For example, the following command adds the phrase "Write-Host 'Hello There'" as a file content to the test.ps1. Because the test.txt file exists already, we use **-force** parameter to replace the existing content.

```PowerShell
PS /home/jen> New-Item -Path ./test.ps1 -Value "Write-Host 'hello there'" -force

    Directory: /home/jen


Mode                LastWriteTime         Length  Name
----                -------------         ------  ----
-a----         7/7/2016   7:19 PM             24  test.ps1

```
There are other ways to add some data to a file, for example, you can use Set-Content to set the file contents:

```PowerShell
PS /home/jen>Set-Content -Path ./test.ps1 -Value "Write-Host 'hello there again!'"
```
Or simply use ">" as below:
```
# create an empty file
"" > empty.txt  

# set "hello world!!!" as content of text.txt file
"hello world!!!" > empty.txt

```
The pound sign (#) above is used for comments in PowerShell.

**7. type - Get-Content**: get the content of an item

```PowerShell
PS /home/jen> Get-Content -Path ./test.ps1
PS /home/jen> type -Path ./test.ps1

"Write-Host 'hello there again!'"
```
**8. del - Remove-Item**: delete a file or folder

This cmdlet will delete the file /home/jen/test.ps1:
```PowerShell
PS /home/jen> Remove-Item ./test.ps1
```
**9. Exit**: - to exit the PowerShell session, type "exit"
```PowerShell
PS /home/jen> exit
```

Need Help?
----
The most important command in PowerShell is possibly the Get-Help, which allows you to quickly learn PowerShell without having to surfing around the Internet. The Get-Help cmdlet also shows you how PowerShell commands work with examples.


PS />**Get-Help**

You can use this cmdlet to get help with any PowerShell commands.

PS />**Get-Help -Name Get-Process**

It shows the syntax and other technical information of the Get-Process cmdlet.


PS />**Get-Help -Name Get-Process -Examples**

It displays the examples how to use the Get-Process cmdlet.
If you use **-full** parameter, i.e., "Get-Help -Name Get-Process -Full", it will display more technical information.



Discover All Commands Available on Your System
----

You want to discover what PowerShell cmdlets available on your system. Simple, just run "Get-Command" as below.

PS /> **Get-Command**

If you want to know whether a particular cmdlet exists on your system, you can do something like below:

PS /> **Get-Command Get-Process**

If you want to know the syntax of Get-Process cmdlet, type

PS /> **Get-Command Get-Process -Syntax**

If you want to know how to sue the get-process, type

PS /> **Get-Help Get-Process -example**


PowerShell Pipeline '|'
----
Sometimes when you run Get-ChildItem or "dir", you want to get a list of files in a descending order. To archive that, type:
```PowerShell
PS /home/jen> dir | sort -Descending
```
Say you want to get the largest file in a directory
```PowerShell
PS /home/jen> dir | Sort-Object -Property Length -Descending | Select-Object -First 1


    Directory: /home/jen


Mode                LastWriteTime       Length  Name
----                -------------       ------  ----
-a----        5/16/2016   1:15 PM        32972  test.log

```
How to Create and Run PowerShell scripts
----
- You can use ISE, VS Code, or any favorite editor to create a PowerShell script and save the script with a .ps1 file extension (helloworld.ps1 in the example)
- To run the script, cd to your current folder and type ./helloworld.ps1

See [Running PowerShell Scripts Is as Easy as 1-2-3] [run-ps] for more details.

[run-ps]:http://windowsitpro.com/powershell/running-powershell-scripts-easy-1-2-3

More Reading
----
Books & eBooks & Blogs & Tutorials
- [Windows PowerShell in Action][in-action] by Bruce Payette
- [Windows PowerShell Cookbook][cookbook] by Lee Holmes
- [eBooks from PowerShell.org](https://powershell.org/ebooks/)
- [eBooks List][ebook-list] by Martin Schvartzman
-	[eBooks from PowerShell.com][ebooks-powershell.com]
- [Tutorial from MVP][tutorial]
-	Script Guy blog: [The best way to Learn PowerShell][to-learn]
-	[Understanding PowerShell Module][ps-module]
-	[How and When to Create PowerShell Module][create-ps-module] by Adam Bertram
-	Video: [Get Started with PowerShell Remoting][remoting] from Channel9
- Video: [PowerShell Remoting in Depth][in-depth] from Channel9
-	[PowerShell Basics: Remote Management][remote-mgmt] from ITPro
- [Running Remote Commands][remote-commands] from PowerShell Web Docs
- [Samples for PowerShell Scripts][examples]
- [Samples for Writing a PowerShell Script Module][examples-ps-module]
- [Writing a PowerShell module in C#][writing-ps-module]
- [Examples of Cmdlets Code][sample-code]


[in-action]: https://www.amazon.com/Windows-PowerShell-Action-Second-Payette/dp/1935182137
[cookbook]: http://shop.oreilly.com/product/9780596801519.do
[ebook-list]: https://blogs.technet.microsoft.com/pstips/2014/05/26/free-powershell-ebooks/
[ebooks-powershell.com]: http://powershell.com/cs/blogs/ebookv2/default.aspx
[tutorial]: http://www.computerperformance.co.uk/powershell/index.htm
[to-learn]:https://blogs.technet.microsoft.com/heyscriptingguy/2015/01/04/weekend-scripter-the-best-ways-to-learn-powershell/
[ps-module]:https://msdn.microsoft.com/en-us/library/dd878324%28v=vs.85%29.aspx
[create-ps-module]:http://www.tomsitpro.com/articles/powershell-modules,2-846.html
[remoting]:https://channel9.msdn.com/Series/GetStartedPowerShell3/06
[in-depth]: https://channel9.msdn.com/events/MMS/2012/SV-B406
[remote-mgmt]:http://windowsitpro.com/powershell/powershell-basics-remote-management
[remote-commands]:https://msdn.microsoft.com/en-us/powershell/scripting/core-powershell/running-remote-commands
[examples]:http://examples.oreilly.com/9780596528492/
[examples-ps-module]:https://msdn.microsoft.com/en-us/library/dd878340%28v=vs.85%29.aspx
[writing-ps-module]:http://www.powershellmagazine.com/2014/03/18/writing-a-powershell-module-in-c-part-1-the-basics/
[sample-code]:https://msdn.microsoft.com/en-us/library/ff602031%28v=vs.85%29.aspx