CLI Windows Powershell Mastery

CLI, Windows & PowerShell Mastery

Purpose

Master command-line operations across all major platforms — Linux/macOS (Bash/Zsh), Windows (PowerShell/CMD), and cross-platform tools — for system administration, automation, development, and troubleshooting.

Bash/Linux Shell Mastery

Essential Patterns

• Piping: command1 | command2 | command3 — chain operations
• Redirection: > (overwrite), >> (append), 2>&1 (stderr to stdout), 2>/dev/null (suppress errors)
• Process substitution: diff <(command1) <(command2)
• Command substitution: result=$(command) or result=`command`
• Here documents: cat <<EOF ... EOF
• Background jobs: command &, nohup command &, jobs, fg, bg

Power Tools

• find: find /path -name "*.py" -mtime -7 -exec grep -l "pattern" {} \;
• grep/ripgrep: rg -i --type py "pattern" /path (ripgrep is 10x faster)
• sed: sed -i 's/old/new/g' file (in-place substitution)
• awk: awk -F',' '{print $2, $4}' data.csv (column extraction)
• xargs: find . -name "*.log" | xargs rm (parallel execution with -P)
• jq: cat data.json | jq '.results[] | {name, value}' (JSON processing)
• curl: curl -s -H "Authorization: Bearer $TOKEN" https://api.example.com/data | jq .
• watch: watch -n 5 'command' (repeat every 5 seconds)
• tmux/screen: Session persistence, split panes, detach/reattach

Shell Scripting Best Practices

• Always use set -euo pipefail at the top of scripts
• Quote all variables: "$variable" not $variable
• Use [[ ]] instead of [ ] for conditionals
• Use $(command) instead of backticks
• Use functions for reusable logic
• Add trap for cleanup on exit
• Use shellcheck for linting

File System Operations

• Disk usage: du -sh */ | sort -rh | head -20
• File counting: find . -type f | wc -l
• Large files: find / -type f -size +100M -exec ls -lh {} \;
• Permissions: chmod, chown, umask
• Links: ln -s target link (symbolic), ln target link (hard)
• Archives: tar -czf archive.tar.gz dir/, tar -xzf archive.tar.gz

Windows PowerShell Mastery

Core Concepts

• Everything is an object — not text streams like Bash
• Verb-Noun naming: Get-Process, Set-Location, New-Item
• Pipeline passes objects: Get-Process | Where-Object {$_.CPU -gt 100} | Sort-Object CPU -Descending
• Aliases exist: ls → Get-ChildItem, cd → Set-Location, cat → Get-Content

Essential Cmdlets

• Get-Help: Get-Help Get-Process -Full (documentation)
• Get-Command: Get-Command *service* (discover commands)
• Get-Member: Get-Process | Get-Member (inspect object properties)
• Select-Object: Get-Process | Select-Object Name, CPU, WorkingSet
• Where-Object: Get-Service | Where-Object {$_.Status -eq 'Running'}
• ForEach-Object: 1..10 | ForEach-Object { $_ * 2 }
• Measure-Object: Get-ChildItem | Measure-Object -Property Length -Sum

System Administration

• Services: Get-Service, Start-Service, Stop-Service, Restart-Service
• Processes: Get-Process, Stop-Process, Start-Process
• Registry: Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion
• Event Logs: Get-EventLog -LogName System -Newest 50
• Network: Test-NetConnection, Get-NetAdapter, Get-NetIPAddress
• Firewall: Get-NetFirewallRule, New-NetFirewallRule
• Users/Groups: Get-LocalUser, Get-LocalGroup, Add-LocalGroupMember
• Scheduled Tasks: Get-ScheduledTask, Register-ScheduledTask

PowerShell Scripting

• Use $ErrorActionPreference = 'Stop' for strict error handling
• Use try/catch/finally for error handling
• Use [CmdletBinding()] for advanced functions
• Use [Parameter(Mandatory)] for required parameters
• Use -WhatIf and -Confirm for destructive operations
• Use Write-Verbose for debug output

Remote Operations

• PSRemoting: Enter-PSSession -ComputerName server01
• Invoke-Command: Invoke-Command -ComputerName server01 -ScriptBlock { Get-Process }
• WinRM: Configure with Enable-PSRemoting -Force

Windows CMD (Legacy but Essential)

Key Commands

• dir: dir /s /b *.txt (recursive, bare format)
• findstr: findstr /s /i "pattern" *.log (grep equivalent)
• robocopy: robocopy source dest /mir /mt:8 (robust file copy)
• netstat: netstat -ano | findstr :80 (network connections)
• tasklist/taskkill: tasklist /fi "imagename eq chrome.exe"
• sfc: sfc /scannow (system file checker)
• DISM: DISM /Online /Cleanup-Image /RestoreHealth
• wmic: wmic os get caption,version (system info)

Cross-Platform Patterns

Equivalent Commands

MCP Integration for Desktop Operations

When operating on a user's Windows computer via MCP:

• Use desktop:{sessionId} prefix for shell sessions
• Files are mounted at /mnt/desktop/C:\
• Prefer PowerShell over CMD for modern Windows
• Always test commands non-destructively first
• Use -WhatIf flag before destructive PowerShell operations
• Check execution policy: Get-ExecutionPolicy
• For GUI automation, use PowerShell with COM objects or UIAutomation

Automation Patterns

Task Automation Checklist

1. Can this be done with a one-liner? (prefer simplicity)
2. Will this be repeated? (write a script)
3. Does it need error handling? (add try/catch or set -e)
4. Does it need logging? (add timestamps and output capture)
5. Does it need scheduling? (cron on Linux, Task Scheduler on Windows)
6. Does it need to be cross-platform? (use Python or Node.js instead)