This repository was created to remember me regarding the powershell and its commands.

What is PowerShell

Microsoft learning platform stated that PowerShell is a cross-platform task automation solution made up of a command-line shell, a scripting language, and a configuration management framework. PowerShell runs on Windows, Linux, and macOS. It is used in many IT-related job roles for tasks that require system management, automation, and scripting.

who will need PowerShell

Cloud Engineers / DevOps Engineers, System Administrators, Network Administrators, Information Security Analysts, Database Administrators (DBAs), Software Engineers, and Data Engineers

1. How to open PowerShell

• PowerShell in Windows: Go to the Start menu, type “PowerShell,” and select Windows PowerShell or Windows PowerShell ISE (the Integrated Scripting Environment).
• Run as Administrator: Right-click on PowerShell and choose "Run as Administrator" if elevated permissions are needed.

2. Basic PowerShell Commands

Here are some basic commands to help you get familiar with PowerShell.

Command	Description
Get-Help	Displays help about commands and syntax.
Get-Command	Lists all available commands in PowerShell.
Get-Process	Displays currently running processes.
Get-Service	Lists all services on the computer.
Get-Location	Shows the current directory.
Set-Location	Changes the current directory (similar to cd).
Clear-Host (or cls)	Clears the console screen.
Get-Content	Reads the contents of a file.

Example:

Get-Help Get-Process

This displays information on how to use the Get-Process command.

3. Navigating the File System

PowerShell allows you to navigate the file system, just like you would in a traditional command line:

• Change directory: Set-Location or cd

  Set-Location "C:\path\to\your\directory"

• List files and folders: Get-ChildItem or ls

  Get-ChildItem

4. Managing Files and Folders

PowerShell provides simple commands to create, copy, move, and delete files and directories.

Command	Description
New-Item	Creates a new file or folder.
Copy-Item	Copies a file or folder.
Move-Item	Moves a file or folder.
Remove-Item	Deletes a file or folder.

Examples:

# Create a new text file
New-Item -Path "C:\path\to\your\file.txt" -ItemType File

# Copy a file
Copy-Item -Path "C:\path\to\your\file.txt" -Destination "C:\path\to\new\location\"

# Move a file
Move-Item -Path "C:\path\to\your\file.txt" -Destination "C:\path\to\new\location\"

# Delete a file
Remove-Item -Path "C:\path\to\your\file.txt"

5. Viewing and Filtering Data

PowerShell is highly effective for viewing and filtering data, especially for system information and file content.

• Filter with Where-Object:

  Get-Process | Where-Object { $_.CPU -gt 100 }

  This shows only processes using more than 100 units of CPU time.

• Select specific properties with Select-Object:

  Get-Process | Select-Object -Property Name, CPU

  This displays only the Name and CPU columns of each process.

6. Using Variables

You can store data in variables for later use in PowerShell by prefixing the variable name with $.

$myVariable = "Hello, PowerShell!"
$number = 42

To print a variable’s value:

Write-Output $myVariable

7. Writing and Reading Text Files

PowerShell makes it easy to create, write, and read text files.

• Write text to a file:

  "Hello, PowerShell!" | Out-File -FilePath "C:\path\to\your\file.txt"

• Read text from a file:

  Get-Content -Path "C:\path\to\your\file.txt"

8. Running Loops and Conditional Statements

PowerShell supports loops (for, foreach, while) and conditional statements (if, else) for automating tasks.

• For loop:

  for ($i = 1; $i -le 5; $i++) {
      Write-Output "Number: $i"
  }

• If statement:

  $num = 5
  if ($num -gt 3) {
      Write-Output "$num is greater than 3"
  } else {
      Write-Output "$num is less than or equal to 3"
  }

9. Working with Processes and Services

• List running processes:

  Get-Process

• Stop a process:

  Stop-Process -Name "notepad" -Force

• List services:

  Get-Service

• Start or stop a service:

  Start-Service -Name "wuauserv"   # Start Windows Update service
  Stop-Service -Name "wuauserv"    # Stop Windows Update service

10. Using PowerShell to Automate Tasks

PowerShell’s scripting capabilities let you automate complex tasks by writing scripts (.ps1 files) that run a series of commands.

• Create a Script:

  1. Open a text editor (such as Notepad) and write your commands.
  2. Save the file with a .ps1 extension, such as MyScript.ps1.

• Run a Script:

  .\MyScript.ps1

  Ensure that PowerShell’s execution policy allows scripts to run:

  Set-ExecutionPolicy RemoteSigned

11 monitor a text file for new lines

• to get all lines in txt file

Get-Content -Path "C:\path\to\your\file.txt" -Wait

• to append text to a file

Add-Content -Path "C:\path\to\your\file.txt" -Value "Your text to append"

• to replace text in a file

(Get-Content -Path "C:\path\to\your\file.txt") -replace 'old text', 'new text' | Set-Content -Path "C:\path\to\your\file.txt"

• to edit specific line

# Read the file into an array, where each line is an element
$file = Get-Content -Path "C:\path\to\your\file.txt"

# Modify a specific line (e.g., line 2)
$file[1] = "This is the new content for line 2"

# Write the modified content back to the file
$file | Set-Content -Path "C:\path\to\your\file.txt"

• to insert Text at a Specific Line

$file = Get-Content -Path "C:\path\to\your\file.txt"

# Insert text at a specific line (e.g., insert after line 2)
$newContent = @("Inserted line")
$file = $file[0..1] + $newContent + $file[2..($file.Count - 1)]

# Write the modified content back to the file
$file | Set-Content -Path "C:\path\to\your\file.txt"

• to remove Lines from a File

$file = Get-Content -Path "C:\path\to\your\file.txt"

# Remove line 2 (e.g., by omitting index 1)
$file = $file | Where-Object { $_ -ne $file[1] }

# Write the updated content back to the file
$file | Set-Content -Path "C:\path\to\your\file.txt"

• to monitor a File for Real-Time Updates

Get-Content -Path "C:\path\to\your\file.txt" -Tail 10 -Wait

12. Tips and Best Practices

• Use Aliases: Many common PowerShell commands have aliases (ls for Get-ChildItem, cd for Set-Location, cat for Get-Content). Use them for quicker access.
• Piping (|): Use the pipeline to chain commands together for efficient processing.
• Error Handling: Use Try and Catch blocks to manage errors in scripts.

Example Script: Automate Backup

To copy files from one folder to another, then create a backup:

$source = "C:\path\to\source\folder"
$destination = "C:\path\to\backup\folder"

# Create the backup folder if it doesn't exist
if (!(Test-Path -Path $destination)) {
    New-Item -ItemType Directory -Path $destination
}

# Copy files
Copy-Item -Path "$source\*" -Destination $destination -Recurse
Write-Output "Backup completed successfully!"

Further Learning

• Explore cmdlets: Use Get-Command and Get-Help to discover and learn new cmdlets.
• Microsoft PowerShell Documentation: Microsoft offers comprehensive documentation, tutorials, and example scripts.