Powershell Core Tutorial for Beginners

PowerShell Core

Powershell Core is an open-source command-line interface (Scripting language ) developed on .NET framework and it can be installed on Windows, Linux, and Mac OS. It helps system administrators to automate day to day tasks.

PowerShell installation on Ubuntu 18.04

To install PowerShell on Ubuntu execute the below commands.

Download the Microsoft repository GPG keys and then register it.

wget -q https://packages.microsoft.com/config/ubuntu/18.04/packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb

Update all packages and add “universe” repositories.

sudo apt-get update
techies@techiescorner:~$ sudo add-apt-repository universe

'universe' distribution component is already enabled for all sources.

Next, install PowerShell

sudo apt-get install -y powershell

To get installed version and the PowerShell terminal execute “pwsh” command.

techies@techiescorner:~$ pwsh 

PowerShell 6.2.4
Copyright (c) Microsoft Corporation. All rights reserved.
https://aka.ms/pscore6-docs
Type 'help' to get help.
PS /home/techies>

PowerShell Installation on MAC OS 10.14.6 

Powershell can be easily installed on MAC OS with a “brew” package installer.

brew cask install powershell

Once installed execute the “pwsh” command to get the version and shell terminal.

MacBook-Pro:~ $ pwsh

PowerShell 6.2.3
Copyright (c) Microsoft Corporation. All rights reserved.
https://aka.ms/pscore6-docs
Type 'help' to get help.
PS /Users/techies> 

There is another method to access PowerShell which is from the Azure portal, log in to your account and on the top right corner, you can see a button named cloud shell. Click on this button to get a shell.

Powershell basic commands

Here we will discuss some basic PowerShell commands. Login to the Ubuntu machine and run “pwsh” to start.

To list files and folders present in the directory enter Get-ChildItem command.

Please note if you enter tab after command it will show suggestions as same as in Linux.

PS /home/techies> Get-C

Get-ChildItem      Get-ComplexResourceQualifier     Get-Credential
Get-Command        Get-ConfigurationErrorCount      Get-Culture          Get-CompatibleVersionAddtionaPropertiesStr          Get-Content   
PS /home/techies> Get-ChildItem
    Directory: /home/techies

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
d-----           1/24/20  6:54 PM        azcopy_linux_amd64_10.3.4     
------           1/24/20  7:20 PM        8754718 azcopy.tar.gz                                   
------           1/2/19 11:49 PM       3132   packages-microsoft-prod.db                                    

 

If we give -Path argument it shows all the files and folder present in the given path. Here I will list all content from the /tmp folder.

PS /home/techies> Get-ChildItem -Path /tmp

    Directory: /tmp
Mode                LastWriteTime     Length   Name
----                -------------     ------   ----
d-r---        12/5/08  3:39 PM                kSar-5.0.6

------        2/19/20 12:13 PM     6039985    kSar-5.0.6.zip

To know the usage of PowerShell command execute Get-Help command as follows.

Get-Help Get-Alias

From the output of the above command, we can understand how to use the command. It is similar to a man page in Linux.

 

The Get-Alias command is to list all Aliases set in the system. A few examples are given below.

PS /home/techies> Get-Alias

CommandType     Name                    Version    Source
-----------     ----                    ------      -----             
Alias           ? -> Where-Object                                     
Alias           % -> ForEach-Object                                  
Alias           cd -> Set-Location                                    
Alias           chdir -> Set-Location                                
Alias          pwd -> Get-Location

 

Pipe command usage

We can pipeline the output of one command with another, an example is given below.

Get-Process | Export-CSV process-lis.csv

Here, the Get-Process command list all running process in the system, the output of this command can be exported to csv file using another command “Export-CSV”

Get-ChildItem | Where-Object Length -gt 10kb

The above “Get-ChildItem” command list all files in the current directory and this output is passed to the next command, there we were given a condition which is the file size is greater than 10kb will be listed. The final output passed into a txt file as follows.

Get-ChildItem | Where-Object Length -gt 10kb | Out-File ./items.txt

To list the content of the “items.txt file use below command.

Get-Content ./items.txt

Powershell remote login

With the help of the “Enter-PSSession” command, we can log in to a remote machine PowerShell terminal.

Enter-PSSession -HostName 192.168.0.15 -UserName techies

Here, we are login to an Ubuntu machine from the MAC PowerShell terminal. The above command asks for the password to login to the machine. The complete output is below.

PS /Users/admin> Enter-PSSession -HostName 192.168.0.15 -UserName techies
techies@192.168.0.15's password: 
[techies@192.168.0.15]: PS /home/techies> 
[techies@192.168.0.15]: PS /home/techies> hostname
techiescorner

It is now connected to the remote terminal. To connect to the Ubuntu machine, we have to add the following line at the sshd_config file of the Ubuntu machine and then restart the sshd service.

Subsystem powershell /usr/bin/pwsh -sshs -NoLogo -NoProfile

AZ module with PowerShell

Azure CLI is a command-line tool  (az tool)  to manage Azure cloud resources. To know more about Azure az I recommend you to read the below article.

Azure az introduction

To install the AZ module for Powershell execute below command.

Install-Module -Name Az -AllowClobber -Scope CurrentUser

The AllowClobber flag helps to override the similar installed module. The CurrentUser flag will install it only for the current logged in user.  To check the installed module execute below command

PS /home/techies> Get-InstalledModule -Name Az -AllVersions                                                                                                                                                        Version     Name        Repository              Description         -------     ----         ----------               -----------                                                                            3.5.0       Az         PSGallery         Microsoft Azure PowerShell - Cmdlets to manage resources in Azure. This module is com…                                                         

Powershell core authentication methods

In this section, we will understand various methods to login to the Azure cloud from the PowerShell command line.

  1. Connect-AzAccount : This is the easy method to connect to the Azure cloud. This command gives a token to authenticate with the cloud. Execute the command in the PowerShell terminal and copy the URL and token mentioned in the output. Once you paste the token in the mentioned URL it prompts to choose an Azure account. Select your account and then come back to the terminal and you can see it listed the Resource group.

2.  Service Principal:  The second method to authenticate with Azure cloud is Service Principle. For this, we need to create a Service Principal from the Azure portal.

To know how to create a service principal and authenticate it with cloud, refer below URL.

How to create an Azure Service Principal

Provisioning a VM from the Powershell.

We have learned basic command of Powershell, next we will a provision a ubuntu virtual machine using Powershell codes.

Login to the PowerShell and execute the below command to connect to the cloud.

PS /home/techies> Connect-AzAccount                                 WARNING: To sign in, use a web browser to open the page https://microsoft.com/devicelogin and enter the code GH5BQ6BZA to authenticate. 

Once you add the token, you can see all the subscriptions under the account.

To create a Virtual machine execute below command.

PS /home/techies> New-AzVM `
>> -Name pshvm `
>> -ResourceGroupName Techies_devops `
>> -Location eastus `
>> -ImageName UbuntuLTS
cmdlet New-AzVM at command pipeline position 1
Supply values for the following parameters:
Credential
User: techies
Password for user techies: *************

Use backquote to write code on a separate line. Also, use the tab for command completion.

The above command creates a VM with default values. Once the job is completed it will display information about the VM in the terminal.

To get complete details about the Virtual machine, log in to the Azure portal and select the resource group.

We have completed the provisioning of a virtual machine from the PowerShell, on the next page we will learn how to deploy a resource from the PowerShell using Azure Resource Manager (ARM)  template.

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