cheatsheet apolzek

Cheatsheet

commands and tricks for day to day

Delete All Commit History on GitHub gitgithub

Reset a repository's commit history by creating an orphan branch

git checkout --orphan latest_branch
git add -A
git commit -am "reset configs"
git branch -D main
git branch -m main
git push -f origin main

Chrome Bookmarks (filter by folder) chromejqlinux

Extract URLs from a specific Chrome bookmark folder using jq

cat ~/.config/google-chrome/Default/Bookmarks \
  | jq -r '.roots.bookmark_bar.children[]
      | select(.name == "tree")
      | .children[]
      | .url'

Chrome Bookmarks (list all) chromejqlinux

List all bookmarks from Chrome's JSON file showing name and URL

cat ~/.config/google-chrome/Default/Bookmarks \
  | jq '.roots.bookmark_bar.children[] | {name: .name, url: .url}'

Chrome Bookmarks (list folders) chromejqlinux

List all Chrome bookmark folders using jq

cat ~/.config/google-chrome/Default/Bookmarks \
  | jq -r '[.. | objects | select(.type == "folder") | .name] | unique | sort | .[]'

Chrome Internals Pages chromedebug
Useful chrome:// internal pages for debugging DNS, events, and proxy settings
```
chrome://net-internals/#dns
chrome://net-internals/#events
chrome://net-internals/#proxy
```

Chrome Bookmarks MacOS(bookmark bar root) chromejqmacos

List all entries from the root of Chrome's bookmarks bar

jq -r '.roots.bookmark_bar.children[]' \
  "$HOME/Library/Application Support/Google/Chrome/Default/Bookmarks"

Post-install Docker dockerlinux
Add current user to docker group after installation
```
sudo usermod -aG docker $USER
exec su -l $USER
groups $USER
docker ps
```

k6 Load Testing k6testingperformance

Basic k6 script with ramp-up, sustained load, and ramp-down stages

import http from 'k6/http';
import { sleep } from 'k6';

export const options = {
    stages: [
        { duration: '10s', target: 100 },
        { duration: '30s', target: 100 },
        { duration: '10s', target: 0 }
    ]
}

export default function () {
    http.get('http://192.168.68.108:3000');
    sleep(1);
}

ntfy Send Notification curlnotification
Send a push notification via ntfy.sh using curl
```
curl -d "Backup successful" ntfy.sh/mytopic
```

curl with --resolve curlnetwork

Force curl to resolve a hostname to a specific IP address, bypassing DNS

curl --resolve
    ::://:
curl --resolve meuservidor.com:8080:192.168.0.100 http://meuservidor.com:8080
curl --resolve google.com:8888:127.0.0.1 https://google.com:8888

Windows Activation (massgrave) windowspowershell
Activate Windows using the massgrave open-source script
```
irm https://massgrave.dev/get | iex
```

View WiFi Passwords linuxwifinetwork

Retrieve saved WiFi passwords on Linux using NetworkManager

ls /etc/NetworkManager/system-connections/
sudo cat /etc/NetworkManager/system-connections/[network-name]
nmcli device wifi list
sudo nmcli connection show "" --show-secrets

Encrypt / Decrypt File with Password opensslsecuritylinux

Use OpenSSL AES-256-CBC with PBKDF2 to encrypt and decrypt files

# Encrypt
echo "Este é um arquivo de teste" > original.txt
openssl enc -aes-256-cbc -salt -pbkdf2 -in original.txt -out secreto.enc

# Decrypt
openssl enc -aes-256-cbc -d -salt -pbkdf2 -in secreto.enc

# Decrypt from remote URL
curl -s https://raw.githubusercontent.com/apolzek/apolzek.github.io/main/secreto.enc \
  | openssl enc -aes-256-cbc -d -salt -pbkdf2

Linux Network Connections linuxnetwork
View all saved NetworkManager connection configs
```
sudo cat /etc/NetworkManager/system-connections/*
```
Set Network Interface MTU linuxnetworkmtu
Lower the MTU on a network interface to avoid packet drops (e.g. on iPhone tethering)
```
sudo ip link set wlp3s0 mtu 1280
```

macOS DNS Commands macosdnsnetwork

Commands for viewing, configuring, and troubleshooting DNS on macOS

# Show current DNS resolver configuration (system-wide)
scutil --dns

# Display DNS servers currently in use (per interface)
networksetup -getdnsservers Wi-Fi

# Set custom DNS servers for Wi-Fi (replace with your desired servers)
sudo networksetup -setdnsservers Wi-Fi 1.1.1.1 8.8.8.8

# Reset DNS back to automatic (DHCP-provided DNS)
sudo networksetup -setdnsservers Wi-Fi empty

# Flush DNS cache (modern macOS)
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

# Query DNS resolution for a domain (low-level system resolver test)
dig example.com

# Alternative DNS lookup tool (simpler output)
nslookup example.com

# Test which DNS server is resolving a domain
dig example.com +short

# Show detailed resolver behavior and search domains
scutil --dns | grep 'nameserver'

# Check current network services (to identify correct interface name)
networksetup -listallnetworkservices

# View DNS configuration for a specific interface (example: Ethernet)
networksetup -getdnsservers Ethernet

# Set DNS for Ethernet interface
sudo networksetup -setdnsservers Ethernet 9.9.9.9 1.1.1.1

Ubuntu Linux DNS Commands linuxubuntudnsnetwork

Commands for viewing, configuring, and troubleshooting DNS on Ubuntu (systemd-resolved and NetworkManager based systems)

# Show current DNS configuration (systemd-resolved)
resolvectl status

# Alternative command (older systems)
systemd-resolve --status

# Show DNS servers currently in use per interface
nmcli dev show | grep DNS

# Show NetworkManager connection profiles
nmcli connection show

# Set DNS servers for a specific connection (replace 'Wired connection 1')
sudo nmcli connection modify "Wired connection 1" ipv4.dns "1.1.1.1 8.8.8.8"

# Ignore DHCP-provided DNS and use manual DNS
sudo nmcli connection modify "Wired connection 1" ipv4.ignore-auto-dns yes

# Restart connection to apply DNS changes
sudo nmcli connection down "Wired connection 1" && sudo nmcli connection up "Wired connection 1"

# Flush DNS cache (systemd-resolved)
sudo resolvectl flush-caches

# Alternative cache restart (forces full reload of resolver)
sudo systemctl restart systemd-resolved

# Query DNS resolution using system resolver
getent hosts example.com

# Query DNS records with dig (recommended tool)
dig example.com

# Query specific DNS record type (A record)
dig example.com A

# Show trace of DNS resolution path
dig example.com +trace

# Simple DNS lookup tool (basic output)
nslookup example.com

# Check /etc/resolv.conf (often symlinked to systemd stub)
cat /etc/resolv.conf

# Verify if systemd stub resolver is active
ls -l /etc/resolv.conf

# Temporarily set DNS by editing resolv.conf (not persistent on most modern systems)
sudo bash -c 'echo -e "nameserver 1.1.1.1\nnameserver 8.8.8.8" > /etc/resolv.conf'

macOS Clipboard Basic Commands macosterminalclipboard
Minimal commands to copy file content to clipboard and paste it back
```
# Copy file content to clipboard using pipe
cat arquivo.txt | pbcopy

# Paste clipboard content in terminal
pbpaste
```

Linux Clipboard (Ubuntu) Equivalent to pbcopy/pbpaste linuxubuntuclipboard

Setup and commands to copy file content to clipboard and paste it back on Ubuntu using xclip or xsel

# Install clipboard utility (xclip)
sudo apt update && sudo apt install -y xclip

# Copy file content to clipboard (equivalent to: cat arquivo.txt | pbcopy)
cat arquivo.txt | xclip -selection clipboard

# Paste clipboard content to terminal (equivalent to pbpaste)
xclip -selection clipboard -o

# Alternative install (xsel instead of xclip)
sudo apt install -y xsel

# Copy file content using xsel
cat arquivo.txt | xsel --clipboard --input

# Paste clipboard content using xsel
xsel --clipboard --output

# Optional aliases for convenience (add to ~/.bashrc or ~/.zshrc)
alias pbcopy='xclip -selection clipboard'
alias pbpaste='xclip -selection clipboard -o'