YubiKey 4 series GPG and SSH setup guide

Written for fairly adept technical users, preferably of Debian GNU/Linux, not for absolute beginners.

You'll probably be working with a single smartcard, so you'll want only one primary key (1. Sign & Certify) and two associated subkeys (2. Encrypt, 3. Authenticate). I've published a Bash function which automates this slightly special key generation process.

YouSysAdmin / fix.sh

Created March 25, 2025 20:39

Fix for using MacOS as remote DOCKER_HOST

	# Context:
	# make sure the URL is valid, and Docker 18.09 or later is installed on the remote host.
	# zsh:1: command not found: docker

	# Add /usr/local/bin to PATH for SSH session
	echo 'PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin' >> ~/.ssh/environment

	# Permit set user environment for SSH session
	sudo sh -c 'echo "PermitUserEnvironment PATH" >> /private/etc/ssh/sshd_config'

YouSysAdmin / theme.yml

Created March 2, 2025 09:24 — forked from r-darwish/theme.yml

Alacritty One Dark Theme


	colors:
	# Default colors
	primary:
	background: '0x1e2127'
	foreground: '0xabb2bf'

	# Bright and dim foreground colors
	#
	# The dimmed foreground color is calculated automatically if it is not present.

YouSysAdmin / schema_auto_increment_columns.sql

Created December 2, 2024 11:28 — forked from bennadel/schema_auto_increment_columns.sql

Looking For Database Performance Bottlenecks And Optimizations Using The Sys Schema In MySQL 5.7

	/**
	* Find the amount of auto-increment "space" has been used. This may can help identify
	* tables that are running out of available ID values.
	*/
	SELECT
	t.table_name,
	t.column_name,
	-- The highest possible ID that can be created with this data-type.
	t.max_value,
	-- The last ID created in this table.

YouSysAdmin / print.go

Last active September 17, 2024 21:29

	// Database Information about RDS instance
	type Database struct {
	// Database identifier
	Identifier string
	// Database ARN
	Arn string
	// Database engine (mysql2, postgres, etc.)
	Engine string
	// Database engine version
	EngineVersion string

YouSysAdmin / mysql-memoryusage.sh

Created August 4, 2023 19:55

Script to get information about used memory by a MySQL server

	#!/bin/sh
	# you might want to add some user authentication here
	mysql -e "show variables; show status" \| awk '
	{
	VAR[$1]=$2
	}
	END {
	MAX_CONN = VAR["max_connections"]
	MAX_USED_CONN = VAR["Max_used_connections"]
	BASE_MEM=VAR["key_buffer_size"] + VAR["query_cache_size"] + VAR["innodb_buffer_pool_size"] + VAR["innodb_additional_mem_pool_size"] + VAR["innodb_log_buffer_size"]

YouSysAdmin / phpenv_macos.md

Created September 21, 2022 08:15

PHPENV + MacOS

Install PHPENV

https://github.com/phpenv/phpenv

Install additional pkg's

brew install \
    autoconf \
 bzip2 \

YouSysAdmin / remove_old_builds.sql

Created March 28, 2021 07:34 — forked from david-zw-liu/remove_old_builds.sql

Keep 1000 builds per repos for DroneCI (sqlite3 version >= 3.25 required)

	-- Thank @sbengo to figure out foreign_keys constraints is defaults to false in sqlite
	-- Enable to delete logs by cascading delete
	PRAGMA foreign_keys = ON;

	WITH n_build_ids_per_repo as (
	SELECT build_id
	FROM (
	SELECT
	build_id,
	build_repo_id,

YouSysAdmin / run-before-shutdown.service

Created October 28, 2020 07:54

Systemd - Run before shutdown/reboot

	# systemd unit file
	# /etc/systemd/system/run-before-shutdown.service
	# TimeoutStartSec - set a timeout for your task or set "0" to disable.
	# When the timeout is turned off and the task "hangs",
	# the process will never be interrupted and the system
	# shutdown will stop
	# Before - Specify the services before which the task should run

	# after add unit file in systemd/system catalogue, "run systemctl daemon-reload"
	# and enable new service "systemctl enable run-before-shutdown.service"

YouSysAdmin / hackthebox.go

Last active March 25, 2020 19:40

	package main

	import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"

Oleksii Samoliuk YouSysAdmin

YubiKey 4 series GPG and SSH setup guide

Written for fairly adept technical users, preferably of Debian GNU/Linux, not for absolute beginners.

PHPENV + MacOS

Install PHPENV

Install additional pkg's