PowerShell vs Linux Commands Guide

A comprehensive comparison between PowerShell and Linux/bash commands for system administrators working across platforms.

Philosophy Differences

| Aspect | PowerShell | Linux/Bash |

|--------|------------|------------|

| Data Type | Works with objects | Works with text streams |

| Output | Structured objects | Plain text |

| Approach | Verb-Noun commands | Short cryptic commands |

| Case Sensitivity | Case insensitive | Case sensitive |

| Help System | Built-in comprehensive help | Man pages + various docs |

---

Basic Navigation and File Operations

Directory Operations

| Task | PowerShell | Linux |

|------|------------|--------|

| Current directory | Get-Location or pwd | pwd |

| Change directory | Set-Location C:\temp or cd C:\temp | cd /tmp |

| List files | Get-ChildItem or ls or dir | ls |

| List with details | Get-ChildItem -Force | ls -la |

| List recursively | Get-ChildItem -Recurse | find . or ls -R |

Examples


# PowerShell
Get-ChildItem -Path C:\temp -Recurse -Force | Where-Object {$_.Extension -eq ".txt"}

# Linux equivalent
find /tmp -name "*.txt" -type f

File Operations

| Task | PowerShell | Linux |

|------|------------|--------|

| Create directory | New-Item -Type Directory -Path C:\folder | mkdir /folder |

| Create file | New-Item -Type File -Path C:\file.txt | touch /file.txt |

| Copy file | Copy-Item source.txt dest.txt | cp source.txt dest.txt |

| Copy directory | Copy-Item -Recurse C:\src C:\dest | cp -r /src /dest |

| Move/rename | Move-Item old.txt new.txt | mv old.txt new.txt |

| Delete file | Remove-Item file.txt | rm file.txt |

| Delete directory | Remove-Item -Recurse -Force folder | rm -rf folder |

Examples


# PowerShell - Copy all .txt files
Get-ChildItem *.txt | Copy-Item -Destination C:\backup

# Linux equivalent
cp *.txt /backup/

---

File Content Operations

Reading Files

| Task | PowerShell | Linux |

|------|------------|--------|

| Display file | Get-Content file.txt | cat file.txt |

| First 10 lines | Get-Content file.txt -TotalCount 10 | head file.txt |

| Last 10 lines | Get-Content file.txt -Tail 10 | tail file.txt |

| Follow/monitor | Get-Content file.txt -Wait | tail -f file.txt |

| Display with line numbers | Get-Content file.txt \| ForEach-Object {$i=1} {"$i: $_"; $i++} | cat -n file.txt` |

Writing Files

| Task | PowerShell | Linux |

|------|------------|--------|

Text Processing

| Task | PowerShell | Linux |

|------|------------|--------|

| Search in files | Select-String "pattern" .txt | grep "pattern" .txt |

| Case insensitive search | Select-String "pattern" .txt | grep -i "pattern" .txt |

| Count lines | (Get-Content file.txt).Count | wc -l file.txt |

| Replace text | (Get-Content file.txt) -replace "old","new" | sed 's/old/new/g' file.txt |

Examples


# PowerShell - Find files containing "error" and show line numbers
Get-ChildItem *.log | Select-String "error" | Select-Object Filename,LineNumber,Line

# Linux equivalent
grep -n "error" *.log

---

System Information

System Details

| Task | PowerShell | Linux |

|------|------------|--------|

| OS Information | Get-ComputerInfo | uname -a |

| Hostname | $env:COMPUTERNAME | hostname |

| Current user | $env:USERNAME | whoami |

| Uptime | (Get-CimInstance Win32_OperatingSystem).LastBootUpTime | uptime |

| System load | Get-Counter "\Processor(_Total)\% Processor Time" | top or htop |

| Memory usage | Get-CimInstance Win32_OperatingSystem | free -h |

| Disk usage | Get-CimInstance Win32_LogicalDisk | df -h |

Examples


# PowerShell - Memory usage percentage
$os = Get-CimInstance Win32_OperatingSystem
$memUsed = ($os.TotalVisibleMemorySize - $os.FreePhysicalMemory) / $os.TotalVisibleMemorySize * 100
Write-Host "Memory Usage: $([math]::Round($memUsed,1))%"

# Linux equivalent
free | awk 'NR==2{printf "Memory Usage: %.1f%%\n", $3*100/$2}'

---

Process Management

Process Operations

| Task | PowerShell | Linux |

|------|------------|--------|

| List processes | Get-Process | ps aux |

| Kill process by name | Stop-Process -Name "notepad" | pkill notepad |

| Kill process by PID | Stop-Process -Id 1234 | kill 1234 |

| Force kill | Stop-Process -Name "app" -Force | kill -9 1234 |

| Start process | Start-Process "notepad.exe" | notepad.exe & |

| Background process | Start-Job { Start-Process "app.exe" } | app.exe & |

Examples


# PowerShell - Find processes using most memory
Get-Process | Sort-Object WorkingSet -Descending | Select-Object -First 5 Name,WorkingSet

# Linux equivalent
ps aux --sort=-%mem | head -5

---

Services Management

| Task | PowerShell | Linux (systemd) |

|------|------------|-----------------|

| List services | Get-Service | systemctl list-units --type=service |

| Service status | Get-Service -Name "Spooler" | systemctl status sshd |

| Start service | Start-Service -Name "Spooler" | systemctl start sshd |

| Stop service | Stop-Service -Name "Spooler" | systemctl stop sshd |

| Restart service | Restart-Service -Name "Spooler" | systemctl restart sshd |

| Enable at boot | Set-Service -Name "Spooler" -StartupType Automatic | systemctl enable sshd |

| Disable at boot | Set-Service -Name "Spooler" -StartupType Disabled | systemctl disable sshd |

---

Network Operations

Network Commands

| Task | PowerShell | Linux |

|------|------------|--------|

| Test connectivity | Test-NetConnection google.com | ping google.com |

| Test specific port | Test-NetConnection google.com -Port 80 | telnet google.com 80 |

| Show IP config | Get-NetIPAddress | ip addr show |

| Show routing table | Get-NetRoute | ip route show |

| DNS lookup | Resolve-DnsName google.com | nslookup google.com |

| Download file | Invoke-WebRequest url -OutFile file | wget url or curl -o file url |

| Show open ports | Get-NetTCPConnection | netstat -tuln |

Examples


# PowerShell - Check if multiple servers are reachable
$servers = @("server1", "server2", "server3")
$servers | ForEach-Object { 
  $result = Test-NetConnection $_ -Port 80 -WarningAction SilentlyContinue
  [PSCustomObject]@{Server=$_; Reachable=$result.TcpTestSucceeded}
}

# Linux equivalent
for server in server1 server2 server3; do
  if timeout 5 bash -c "</dev/tcp/$server/80"; then
    echo "$server: Reachable"
  else
    echo "$server: Not reachable"
  fi
done

---

Variables and Environment

Variable Syntax

| Concept | PowerShell | Linux/Bash |

|---------|------------|------------|

| Variable assignment | $name = "John" | name="John" |

| Variable access | $name | $name |

| Environment variables | $env:PATH | $PATH |

| Command substitution | $date = Get-Date | date=$(date) |

| Array | $arr = @("a","b","c") | arr=("a" "b" "c") |

| Array access | $arr[0] | ${arr[0]} |

Environment Variables

| Task | PowerShell | Linux |

|------|------------|--------|

| List all env vars | Get-ChildItem env: | env or printenv |

| Get specific var | $env:PATH | echo $PATH |

| Set env var | $env:MYVAR = "value" | export MYVAR="value" |

| Set permanent var | [Environment]::SetEnvironmentVariable("MYVAR","value","User") | Add to ~/.bashrc |

---

Scripting Concepts

Basic Script Structure

PowerShell Script (.ps1)


#!/usr/bin/env pwsh

# Parameters
param(
    [string]$ServerName = "localhost",
    [int]$Port = 80
)

# Function
function Test-Connection {
    param($Server, $Port)
    $result = Test-NetConnection $Server -Port $Port
    return $result.TcpTestSucceeded
}

# Main logic
if (Test-Connection $ServerName $Port) {
    Write-Host "Server $ServerName is reachable on port $Port" -ForegroundColor Green
} else {
    Write-Host "Server $ServerName is NOT reachable on port $Port" -ForegroundColor Red
}

Bash Script (.sh)


#!/bin/bash

# Parameters with defaults
SERVER_NAME=${1:-localhost}
PORT=${2:-80}

# Function
test_connection() {
    local server=$1
    local port=$2
    timeout 5 bash -c "</dev/tcp/$server/$port" 2>/dev/null
    return $?
}

# Main logic
if test_connection "$SERVER_NAME" "$PORT"; then
    echo -e "\033[32mServer $SERVER_NAME is reachable on port $PORT\033[0m"
else
    echo -e "\033[31mServer $SERVER_NAME is NOT reachable on port $PORT\033[0m"
fi

Conditional Logic

PowerShell


if ($age -ge 18) {
    Write-Host "Adult"
} elseif ($age -ge 13) {
    Write-Host "Teenager"
} else {
    Write-Host "Child"
}

# Switch statement
switch ($day) {
    "Monday" { "Start of work week" }
    "Friday" { "TGIF!" }
    default { "Regular day" }
}

Bash


if [ $age -ge 18 ]; then
    echo "Adult"
elif [ $age -ge 13 ]; then
    echo "Teenager"
else
    echo "Child"
fi

# Case statement
case $day in
    "Monday") echo "Start of work week" ;;
    "Friday") echo "TGIF!" ;;
    *) echo "Regular day" ;;
esac

Loops

PowerShell


# ForEach
$fruits = @("apple", "banana", "cherry")
foreach ($fruit in $fruits) {
    Write-Host "I like $fruit"
}

# For loop
for ($i = 1; $i -le 10; $i++) {
    Write-Host "Count: $i"
}

# While loop
$count = 1
while ($count -le 5) {
    Write-Host "Count: $count"
    $count++
}

Bash


# For loop with array
fruits=("apple" "banana" "cherry")
for fruit in "${fruits[@]}"; do
    echo "I like $fruit"
done

# For loop with range
for i in {1..10}; do
    echo "Count: $i"
done

# While loop
count=1
while [ $count -le 5 ]; do
    echo "Count: $count"
    ((count++))
done

---

Error Handling

PowerShell


try {
    $result = Get-Content "nonexistent.txt"
} catch {
    Write-Error "File not found: $($_.Exception.Message)"
} finally {
    Write-Host "Cleanup code here"
}

# Check last command success
if ($?) {
    Write-Host "Command succeeded"
} else {
    Write-Host "Command failed"
}

Bash


# Simple error handling
if ! cp source.txt dest.txt 2>/dev/null; then
    echo "Copy failed" >&2
    exit 1
fi

# Check exit code
if [ $? -eq 0 ]; then
    echo "Command succeeded"
else
    echo "Command failed"
fi

# Set error handling
set -e  # Exit on any error
set -u  # Exit on undefined variable

---

Package Management

|------|------------|----------------------|-------------------|

---

File Permissions and Users

Permissions

| Task | PowerShell | Linux |

|------|------------|--------|

| Show permissions | Get-Acl C:\file.txt | ls -l file.txt |

| Change permissions | Set-Acl -Path C:\file.txt -AclObject $acl | chmod 755 file.txt |

| Change owner | Complex ACL operations | chown user:group file.txt |

User Management

| Task | PowerShell | Linux |

|------|------------|--------|

| Current user | $env:USERNAME | whoami |

| List users | Get-LocalUser | cat /etc/passwd |

| Add user | New-LocalUser -Name "user" | useradd user |

| User groups | Get-LocalGroup | groups or id |

---

Useful One-liners

PowerShell


# Find large files
Get-ChildItem C:\ -Recurse | Where-Object {$_.Length -gt 100MB} | Sort-Object Length -Descending

# Find files modified in last 7 days
Get-ChildItem -Recurse | Where-Object {$_.LastWriteTime -gt (Get-Date).AddDays(-7)}

# Check disk space on all drives
Get-CimInstance Win32_LogicalDisk | Select-Object DeviceID,@{n='Size(GB)';e={[math]::Round($_.Size/1GB,2)}},@{n='Free(GB)';e={[math]::Round($_.FreeSpace/1GB,2)}}

# Find duplicate files by hash
Get-ChildItem -Recurse | Get-FileHash | Group-Object Hash | Where-Object {$_.Count -gt 1}

Linux


# Find large files
find / -type f -size +100M -exec ls -lh {} \; 2>/dev/null | sort -k5 -hr

# Find files modified in last 7 days
find . -type f -mtime -7

# Check disk space
df -h

# Find duplicate files by hash
find . -type f -exec md5sum {} \; | sort | uniq -d -w 32

---

Key Differences Summary

PowerShell Advantages

Object-oriented: Rich data structures, easy property access
Consistent syntax: Verb-Noun pattern, predictable parameters
Built-in help: Comprehensive documentation with examples
Cross-platform: Runs on Windows, Linux, macOS
Integration: Deep Windows system integration
Type safety: Strong typing prevents many errors

Linux/Bash Advantages

Performance: Generally faster for text processing
Ubiquity: Available on virtually all Unix-like systems
Simplicity: Short commands for common tasks
Pipes: Excellent text stream processing
History: Decades of scripts and knowledge
Resource usage: Lower memory footprint

When to Use What

Use PowerShell when:

Working primarily on Windows
Need rich object manipulation
Want consistent, discoverable commands
Working with .NET applications
Need strong error handling

Use Linux/Bash when:

Working on Unix-like systems
Processing large text files
Need maximum performance
Working with traditional Unix tools
Want minimal system dependencies

---

Cross-Platform PowerShell

PowerShell Core (6+) runs on Linux too! Install with:


# Ubuntu/Debian
sudo apt install powershell

# RHEL/CentOS
sudo yum install powershell

# Run PowerShell on Linux
pwsh

This gives you PowerShell's object-oriented approach on Linux systems, combining the best of both worlds!