312 lines
11 KiB
Markdown
312 lines
11 KiB
Markdown
PowerShell Beginner’s Guide
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====
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If you are new to PowerShell, this document will walk you through a few examples to give you some basic ideas of PowerShell.
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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.
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Launch PowerShell Console/Session
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---
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First you need to launch a PowerShell session by following the [Installing PowerShell Guide](./learning-powershell.md#installing-powershell).
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Getting Familiar with PowerShell Commands
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---
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In this section, you will learn how to
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- create a file, delete a file and change file directory
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- discover what version of PowerShell you are currently using
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- exit a PowerShell session
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- get help if you needed
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- find syntax of PowerShell cmdlets
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- and more
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As mentioned above, PowerShell commands are designed to have Verb-Noun structure, for instance Get-Process, Set-Location, Clear-Host, etc.
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Let’s exercise some of the basic PowerShell commands, also known as **cmdlets**.
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Please note that we will use the PowerShell prompt sign **PS />** as it appears on Linux in the following examples.
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It is shown as **PS C:\\>** on Windows.
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**1. Get-Process**: Gets the processes that are running on the local computer or a remote computer.
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By default, you will get data back similar to the following:
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``` PowerShell
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PS /> Get-Process
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Handles NPM(K) PM(K) WS(K) CPU(s) Id ProcessName
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------- ------ ----- ----- ------ -- -----------
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- - - 1 0.012 12 bash
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- - - 21 20.220 449 powershell
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- - - 11 61.630 8620 code
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- - - 74 403.150 1209 firefox
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…
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```
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Only interested in the instance of firefox process that are running on your computer?
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Try this:
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```PowerShell
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PS /> Get-Process -Name firefox
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Handles NPM(K) PM(K) WS(K) CPU(s) Id ProcessName
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------- ------ ----- ----- ------ -- -----------
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- - - 74 403.150 1209 firefox
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```
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Want to get back more than one process?
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Then just specify process names and separate them with commas.
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```PowerShell
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PS /> Get-Process -Name firefox, powershell
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Handles NPM(K) PM(K) WS(K) CPU(s) Id ProcessName
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------- ------ ----- ----- ------ -- -----------
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- - - 74 403.150 1209 firefox
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- - - 21 20.220 449 powershell
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```
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**2. Clear-Host**: Clears the display in the host program.
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```PowerShell
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PS /> Get-Process
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PS /> Clear-Host
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```
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Type too much just for clearing the screen?
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Here is how the alias can help.
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**3. Get-Alias**: Gets the aliases for the current session.
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```PowerShell
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PS /> Get-Alias
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CommandType Name
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----------- ----
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…
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Alias cd -> Set-Location
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Alias cls -> Clear-Host
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Alias copy -> Copy-Item
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Alias dir -> Get-ChildItem
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Alias gc -> Get-Content
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Alias gmo -> Get-Module
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Alias ri -> Remove-Item
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Alias type -> Get-Content
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…
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As you can see "cls" is an alias of Clear-Host.
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Now try it:
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PS /> Get-Process
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PS /> cls
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```
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**4. cd - Set-Location**: Sets the current working location to a specified location.
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```PowerShell
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PS /> Set-Location /home
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PS /home>
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```
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**5. dir - Get-ChildItem**: Gets the items and child items in one or more specified locations.
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```PowerShell
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Get all files under the current directory:
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PS /> Get-ChildItem
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Get all files under the current directory as well as its subdirectories:
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PS /> cd $home
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PS /home/jen> dir -Recurse
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List all files with "txt" file extension.
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PS /> cd $home
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PS /home/jen> dir –Path *.txt -Recurse
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```
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**6. New-Item**: Creates a new item.
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```PowerShell
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An empty file is created if you type the following:
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PS /home/jen> New-Item -Path ./test.txt
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Directory: /home/jen
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Mode LastWriteTime Length Name
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---- ------------- ------ ----
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-a---- 7/7/2016 7:17 PM 0 test.txt
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```
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You can use the **-Value** parameter to add some data to your file.
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For example, the following command adds the phrase "Hello world!" as a file content to the test.txt.
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Because the test.txt file exists already, we use **-Force** parameter to replace the existing content.
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```PowerShell
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PS /home/jen> New-Item -Path ./test.txt -Value "Hello world!" -Force
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Directory: /home/jen
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Mode LastWriteTime Length Name
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---- ------------- ------ ----
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-a---- 7/7/2016 7:19 PM 24 test.txt
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```
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There are other ways to add some data to a file.
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For example, you can use Set-Content to set the file contents:
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```PowerShell
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PS /home/jen>Set-Content -Path ./test.txt -Value "Hello world again!"
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```
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Or simply use ">" as below:
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```
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# create an empty file
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"" > test.txt
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# set "Hello world!" as content of test.txt file
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"Hello world!!!" > test.txt
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```
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The pound sign (#) above is used for comments in PowerShell.
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**7. type - Get-Content**: Gets the content of the item at the specified location.
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```PowerShell
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PS /home/jen> Get-Content -Path ./test.txt
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PS /home/jen> type -Path ./test.txt
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Hello world again!
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```
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**8. del - Remove-Item**: Deletes the specified items.
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This cmdlet will delete the file /home/jen/test.txt:
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```PowerShell
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PS /home/jen> Remove-Item ./test.txt
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```
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**9. $PSVersionTable**: Displays the version of PowerShell you are currently using.
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Type **$PSVersionTable** in your PowerShell session, you will see something like below.
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"PSVersion" indicates the PowerShell version that you are using.
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```PowerShell
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Name Value
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---- -----
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PSVersion 5.1.10032.0
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PSEdition Linux
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PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
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BuildVersion 3.0.0.0
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CLRVersion
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WSManStackVersion 1.0
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PSRemotingProtocolVersion 2.3
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SerializationVersion 1.1.0.1
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```
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**10. Exit**: To exit the PowerShell session, type "exit".
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```PowerShell
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PS /home/jen> exit
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```
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Need Help?
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----
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The most important command in PowerShell is possibly the Get-Help, which allows you to quickly learn PowerShell without having to search around the internet.
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The Get-Help cmdlet also shows you how PowerShell commands work with examples.
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It shows the syntax and other technical information of the Get-Process cmdlet.
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```PowerShell
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PS /> Get-Help -Name Get-Process
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```
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It displays the examples how to use the Get-Process cmdlet.
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```PowerShell
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PS />**Get-Help -Name Get-Process -Examples**
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```
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If you use **-Full** parameter, for example, `Get-Help -Name Get-Process -Full`, it will display more technical information.
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Discover Commands Available on Your System
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----
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You want to discover what PowerShell cmdlets available on your system? Just run "Get-Command" as below:
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```PowerShell
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PS /> Get-Command
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```
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If you want to know whether a particular cmdlet exists on your system, you can do something like below:
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```PowerShell
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PS /> Get-Command Get-Process
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```
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If you want to know the syntax of Get-Process cmdlet, type:
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```PowerShell
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PS /> Get-Command Get-Process -Syntax
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```
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If you want to know how to use the Get-Process, type:
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```PowerShell
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PS /> Get-Help Get-Process -Example
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```
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PowerShell Pipeline '|'
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----
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Sometimes when you run Get-ChildItem or "dir", you want to get a list of files and folders in a descending order.
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To achieve that, type:
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```PowerShell
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PS /home/jen> dir | sort -Descending
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```
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Say you want to get the largest file in a directory
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```PowerShell
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PS /home/jen> dir | Sort-Object -Property Length -Descending | Select-Object -First 1
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Directory: /home/jen
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Mode LastWriteTime Length Name
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---- ------------- ------ ----
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-a---- 5/16/2016 1:15 PM 32972 test.log
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```
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How to Create and Run PowerShell scripts
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----
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- You can use ISE, Visual Studio Code or your favorite editor to create a PowerShell script and save the script with a .ps1 file extension (for example, helloworld.ps1)
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- To run the script, cd to your current folder and type ./yourscript.ps1 (for example, ./helloworld.ps1).
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Note: If you are using Windows, make sure you set the PowerShell's execution policy to "RemoteSigned" in this case.
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See [Running PowerShell Scripts Is as Easy as 1-2-3] [run-ps] for more details.
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[run-ps]:http://windowsitpro.com/powershell/running-powershell-scripts-easy-1-2-3
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Recommended Training and Reading
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----
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- Video: [Get Started with PowerShell][remoting] from Channel9
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- [eBooks from PowerShell.org](https://powershell.org/ebooks/)
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- [eBooks from PowerShell.com][ebooks-powershell.com]
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- [eBooks List][ebook-list] by Martin Schvartzman
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- [Tutorial from MVP][tutorial]
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- Script Guy blog: [The best way to Learn PowerShell][to-learn]
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- [Understanding PowerShell Module][ps-module]
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- [How and When to Create PowerShell Module][create-ps-module] by Adam Bertram
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- Video: [PowerShell Remoting in Depth][in-depth] from Channel9
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- [PowerShell Basics: Remote Management][remote-mgmt] from ITPro
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- [Running Remote Commands][remote-commands] from PowerShell Web Docs
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- [Samples for PowerShell Scripts][examples]
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- [Samples for Writing a PowerShell Script Module][examples-ps-module]
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- [Writing a PowerShell module in C#][writing-ps-module]
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- [Examples of Cmdlets Code][sample-code]
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Commercial Resources
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----
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- [Windows PowerShell in Action][in-action] by Bruce Payette
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- [Windows PowerShell Cookbook][cookbook] by Lee Holmes
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[in-action]: https://www.amazon.com/Windows-PowerShell-Action-Second-Payette/dp/1935182137
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[cookbook]: http://shop.oreilly.com/product/9780596801519.do
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[ebook-list]: https://blogs.technet.microsoft.com/pstips/2014/05/26/free-powershell-ebooks/
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[ebooks-powershell.com]: http://powershell.com/cs/blogs/ebookv2/default.aspx
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[tutorial]: http://www.computerperformance.co.uk/powershell/index.htm
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[to-learn]:https://blogs.technet.microsoft.com/heyscriptingguy/2015/01/04/weekend-scripter-the-best-ways-to-learn-powershell/
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[ps-module]:https://msdn.microsoft.com/en-us/library/dd878324%28v=vs.85%29.aspx
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[create-ps-module]:http://www.tomsitpro.com/articles/powershell-modules,2-846.html
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[remoting]:https://channel9.msdn.com/Series/GetStartedPowerShell3/06
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[in-depth]: https://channel9.msdn.com/events/MMS/2012/SV-B406
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[remote-mgmt]:http://windowsitpro.com/powershell/powershell-basics-remote-management
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[remote-commands]:https://msdn.microsoft.com/en-us/powershell/scripting/core-powershell/running-remote-commands
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[examples]:http://examples.oreilly.com/9780596528492/
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[examples-ps-module]:https://msdn.microsoft.com/en-us/library/dd878340%28v=vs.85%29.aspx
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[writing-ps-module]:http://www.powershellmagazine.com/2014/03/18/writing-a-powershell-module-in-c-part-1-the-basics/
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[sample-code]:https://msdn.microsoft.com/en-us/library/ff602031%28v=vs.85%29.aspx
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