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Windows Command Line & PowerShell

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CompTIA A+ 220-1201 & 220-1202

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1 Introduction & Exam Overview

About the CompTIA A+ Certification Exam Domains & Study Strategy

2 Core 1 Domain 1: Mobile Devices (13%)

Laptop Hardware & Components Laptop Features & Display Types Mobile Device Connectivity & Accessories Mobile Operating System Features Mobile Device Synchronization & Data Transfer

3 Core 1 Domain 2: Networking (23%)

TCP/IP Fundamentals & the OSI Model Common Ports & Protocols Wireless Networking Standards Network Hardware & Devices Network Configuration & Internet Connections Network Types & Topologies

4 Core 1 Domain 3: Hardware (25%)

Cables & Connectors RAM Types & Storage Devices Motherboards, CPUs & Power Supplies Printers & Multifunction Devices Peripheral Devices & Expansion Cards Network Cable Tools & Testing

5 Core 1 Domain 4: Virtualization & Cloud Computing (11%)

Virtualization Concepts Cloud Computing Models & Services Client-Side Virtualization in Practice

6 Core 1 Domain 5: Hardware & Network Troubleshooting (28%)

CompTIA Troubleshooting Methodology Hardware Troubleshooting Network Troubleshooting Printer Troubleshooting Display & Mobile Device Troubleshooting

7 Core 2 Domain 1: Operating Systems (28%)

Windows Editions & Features Windows Administrative Tools & Utilities Windows Command Line & PowerShell macOS & Linux Basics Windows Networking & File Sharing Windows Installation & Upgrade Methods

8 Core 2 Domain 2: Security (28%)

Physical & Logical Security Measures Malware Types & Threat Mitigation Wireless & Network Security Encryption & Data Protection

9 Core 2 Domain 3: Software Troubleshooting (23%)

Windows OS Troubleshooting Mobile OS & Application Troubleshooting Browser & Application Troubleshooting

10 Core 2 Domain 4: Operational Procedures (21%)

Documentation & Change Management Backup & Recovery Methods Safety & Environmental Procedures Scripting & Remote Access Technologies Privacy, Licensing & Organizational Policies

Windows Command Line & PowerShell

Key Takeaways Explain This Topic AI

Command Prompt (cmd.exe) uses legacy DOS-style commands while PowerShell uses Verb-Noun cmdlets (Get-Process, Stop-Service) and pipelines for automation.

File commands cd, dir, copy, xcopy, robocopy, md, rd, del, and ren handle navigation and file management; robocopy /mir mirrors directories and survives network interruptions.

Repair commands run elevated: sfc /scannow fixes protected system files, DISM /Online /Cleanup-Image /RestoreHealth repairs the component store, and chkdsk /f /r fixes errors and bad sectors.

When system files are corrupt, run DISM first to repair the source component store, then run sfc /scannow so it has a clean source to copy from.

Many commands (sfc, DISM, diskpart, chkdsk on the system drive, net stop) require an elevated 'Run as administrator' prompt or they fail with access-denied.

Last updated: October 2026

Command Prompt Essentials

The Command Prompt (cmd.exe) is the legacy DOS-style shell. Many commands need an elevated session — right-click and choose Run as administrator , or they fail with "Access is denied."

File and directory commands

  • Command Purpose Example
  • cd Change directory (cd .. goes up) cd C:\Users\Jo\Documents
  • dir List contents (/a shows hidden) dir /a
  • md / mkdir Make a directory md C:\Logs
  • rd / rmdir Remove a directory (/s = contents) rd C:\Old /s
  • copy Copy a single file copy a.txt D:\
  • xcopy Copy trees xcopy C:\Src D:\Dst /s /e
  • robocopy Robust mirror copy robocopy C:\Src D:\Dst /mir
  • move / ren Move or rename ren old.txt new.txt
  • del Delete files del *.tmp
  • type / cls Show file / clear screen type readme.txt

Why robocopy? For large data sets or flaky network shares, robocopy /mir mirrors a source to a destination, copies only changed files, retries on failure, and preserves attributes — far more reliable than copy or xcopy.

System and repair commands (elevated)

  • Command Purpose
  • sfc /scannow Scan and repair protected system files
  • DISM /Online /Cleanup-Image /RestoreHealth Repair the Windows component store
  • chkdsk C: /f /r Fix file-system errors (/f) and locate bad sectors (/r)
  • shutdown /s /t 0 Shut down now (/r restarts)
  • tasklist / taskkill /PID n /F List / force-kill processes
  • systeminfo / winver System details / Windows version
  • gpupdate /force / gpresult /r Refresh / report applied Group Policy
  • Disk and network commands
  • Command Purpose
  • diskpart Interactive command-line disk management
  • format D: /FS:NTFS Format a volume as NTFS
  • convert D: /FS:NTFS Convert FAT32 to NTFS without data loss
  • ipconfig / ping / tracert / nslookup / netstat Network diagnostics
  • net user / net share / net use Z: \\SRV\Share Accounts, shares, mapped drives
  • System File Checker, DISM, and Order of Operations

System File Checker (sfc /scannow) replaces corrupt or missing protected OS files using copies from the local component store . If that store is itself damaged, sfc cannot repair and reports it could not fix some files.

DISM (Deployment Image Servicing and Management) with /Online /Cleanup-Image /RestoreHealth repairs the component store, pulling clean files from Windows Update.

Correct order: Run DISM /RestoreHealth first to heal the component store, then run sfc /scannow so it has a trustworthy source to copy from. Running sfc first on a corrupt store wastes time.

For disk-level corruption (bad sectors, file-table errors) the tool is chkdsk , not sfc. chkdsk C: /f /r schedules a check at next reboot because the system volume is locked while Windows runs.

PowerShell

PowerShell is the modern object-oriented shell built on .NET. Its commands are cmdlets in a strict Verb-Noun format, which makes them discoverable.

  • Cmdlet cmd equivalent Purpose
  • Get-Process tasklist List processes
  • Stop-Process taskkill End a process
  • Get-Service / Start-Service / Stop-Service net start/stop Manage services
  • Get-ChildItem dir List items
  • Copy-Item / Remove-Item copy / del Copy / delete
  • Get-Help help Command help

Key concepts:

The pipeline (|) passes objects, not just text: Get-Process | Sort-Object CPU -Descending .

Execution Policy governs whether scripts run: Set-ExecutionPolicy RemoteSigned allows local scripts plus signed remote ones, a common secure default.

Because PowerShell handles .NET objects , you can filter and format properties directly rather than parsing screen text.

Elevation, Switches, and Common Exam Traps

The most frequent command-line mistake on the exam is forgetting elevation . Commands that touch protected system state — sfc , DISM , diskpart , chkdsk on the system volume, net stop/start of a service, and format of a system disk — must run in a prompt opened with Run as administrator . If a scenario says a technician ran sfc /scannow and got "You must be an administrator," the fix is not a different command; it is reopening the prompt elevated. Standard cmd and PowerShell windows run with the user's normal token and will refuse these operations.

Switches change behavior in ways the exam loves to test. For chkdsk , /f fixes file-system metadata while /r additionally scans for and recovers data from bad sectors (and implies /f); because /r reads the entire surface it is far slower. For xcopy and robocopy , the difference is durability: xcopy /s /e copies subdirectories (including empty ones with /e), whereas robocopy /mir mirrors a tree, deletes destination files no longer in the source, retries on failure, and is the right answer for large or networked transfers. For shutdown , /s shuts down, /r restarts, and /t 0 removes the countdown delay.

A subtle distinction is gpupdate versus gpresult . gpupdate /force re-applies Group Policy immediately, which you run after a policy change has not taken effect; gpresult /r only reports which policies currently apply, which you run to diagnose why a setting did or did not land. Confusing the two is a common wrong answer.

PowerShell vs. cmd choice: When a task is a one-off interactive command, either shell works, but anything involving filtering objects, scripting, or remote management favors PowerShell. A scenario that asks you to "get the top five processes by memory and stop one" is naturally a PowerShell pipeline ( Get-Process | Sort-Object WS -Descending ), not a cmd task. Also recall that Set-ExecutionPolicy gates whether scripts run at all — a script that fails with "running scripts is disabled on this system" is an execution-policy problem, fixed with RemoteSigned, not a syntax error in the script.