PowerShell vs Bash vs CMD comparison

Introduction

You want to know the differences between PowerShell, Bash, and CMD so you can pick the right tool for your tasks.

You need to automate tasks on Windows computers.

You want to write scripts that work on Linux or macOS.

You want to run simple commands quickly on Windows.

You want to manage system settings or files with powerful commands.

You want to understand which shell fits your daily work best.

Syntax

PowerShell

PowerShell: Uses cmdlets like Get-Process
Bash: Uses commands like ls, grep
CMD: Uses commands like dir, copy

PowerShell uses objects, not just text, which makes it powerful.

Bash is common on Linux and macOS, CMD is older and Windows-only.

Examples

Lists processes using more than 100 CPU seconds.

PowerShell

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

Shows processes related to Firefox.

PowerShell

Bash:
ps aux | grep firefox

Finds Firefox processes in the task list.

PowerShell

CMD:
tasklist | findstr firefox

Sample Program

This script shows how to list files in each shell. PowerShell uses Get-ChildItem, Bash uses ls, CMD uses dir.

PowerShell

Write-Output "PowerShell: List files"
Get-ChildItem

Write-Output "Bash: List files"
# bash command: ls -l

Write-Output "CMD: List files"
# cmd command: dir

Important Notes

PowerShell works well on Windows and now also on Linux and macOS.

Bash is great for Linux/macOS but can be installed on Windows too.

CMD is simple but less powerful than PowerShell or Bash.

Summary

PowerShell is object-based and powerful for Windows automation.

Bash is text-based and common on Linux/macOS for scripting.

CMD is basic and mostly used for simple Windows commands.

Practice

1. Which shell is object-based and primarily designed for Windows automation?

easy

A. CMD

B. Bash

C. PowerShell

D. Zsh

Solution

1. Step 1: Understand shell types

   PowerShell is known for handling objects, unlike Bash and CMD which handle text.

2. Step 2: Identify platform focus

   PowerShell is designed mainly for Windows automation, while Bash is common on Linux/macOS and CMD is basic Windows shell.

3. Final Answer:

   PowerShell -> Option C

4. Quick Check:

   Object-based Windows shell = PowerShell [OK]

Hint: PowerShell = objects + Windows automation [OK]

Common Mistakes:

• Confusing Bash as object-based
• Thinking CMD is object-based
• Selecting shells not related to Windows

2. Which of the following is the correct way to list files in PowerShell?

easy

A. ls -l

B. listfiles

C. dir /w

D. Get-ChildItem

Solution

1. Step 1: Recall PowerShell commands

   PowerShell uses cmdlets like Get-ChildItem to list files.

2. Step 2: Compare with other shells

   ls -l is Bash/Linux syntax, dir /w is CMD syntax, listfiles is invalid.

3. Final Answer:

   Get-ChildItem -> Option D

4. Quick Check:

   PowerShell file list = Get-ChildItem [OK]

Hint: PowerShell cmdlets start with Get- or Set- [OK]

Common Mistakes:

• Using Bash command ls -l in PowerShell
• Using CMD dir /w in PowerShell
• Typing invalid commands like listfiles

3. What will be the output of this PowerShell command?

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

medium

A. Lists all processes with CPU usage less than 100 seconds

B. Lists all processes with CPU usage greater than 100 seconds

C. Shows an error because CPU property does not exist

D. Lists all processes regardless of CPU usage

Solution

1. Step 1: Understand Get-Process output

   Get-Process returns process objects with a CPU property showing CPU time in seconds.

2. Step 2: Analyze Where-Object filter

   The filter $_.CPU -gt 100 selects processes with CPU time greater than 100 seconds.

3. Final Answer:

   Lists all processes with CPU usage greater than 100 seconds -> Option B

4. Quick Check:

   Filter CPU > 100 seconds = Lists all processes with CPU usage greater than 100 seconds [OK]

Hint: Where-Object filters objects by property conditions [OK]

Common Mistakes:

• Confusing greater than (gt) with less than
• Assuming CPU property is missing
• Thinking it lists all processes without filtering

4. Identify the error in this PowerShell command that tries to list files:

ls -l | grep ".txt"

medium

A. PowerShell does not support ls -l syntax

B. grep is not a native PowerShell command

C. Quotes around .txt should be single quotes

D. The pipe symbol | is invalid in PowerShell

Solution

1. Step 1: Check command compatibility

   PowerShell supports ls alias but not with -l option; it uses Get-ChildItem instead.

2. Step 2: Identify grep usage

   grep is a Linux command, not native in PowerShell; PowerShell uses Where-Object or Select-String.

3. Final Answer:

   PowerShell does not support ls -l syntax -> Option A

4. Quick Check:

   ls -l syntax unsupported = PowerShell does not support ls -l syntax [OK]

Hint: PowerShell ls alias lacks Bash -l flag [OK]

Common Mistakes:

• Assuming ls -l works fully in PowerShell
• Thinking pipe | is invalid
• Believing quote style causes error here

5. You want to write a script that works on Windows and Linux to list files. Which approach is best?

hard

A. Write a PowerShell script using Get-ChildItem and run PowerShell Core on both OS

B. Write a Bash script using ls and run it only on Linux

C. Write a CMD batch file using dir and run it on Windows only

D. Write separate scripts for each OS and manually switch

Solution

1. Step 1: Consider cross-platform support

   PowerShell Core (PowerShell 7+) runs on Windows and Linux, supporting Get-ChildItem on both.

2. Step 2: Evaluate other options

   Bash scripts work only on Linux/macOS; CMD batch files only on Windows; separate scripts add complexity.

3. Final Answer:

   Write a PowerShell script using Get-ChildItem and run PowerShell Core on both OS -> Option A

4. Quick Check:

   Cross-platform scripting = PowerShell Core + Get-ChildItem [OK]

Hint: PowerShell Core runs cross-platform, unlike CMD or Bash alone [OK]

Common Mistakes:

• Assuming Bash works on Windows by default
• Thinking CMD scripts run on Linux
• Ignoring cross-platform PowerShell Core availability