#!/bin/bash

####################################################################################################
#### author: SlickStack ############################################################################
#### link: https://slickstack.io ###################################################################
#### mirror: https://mirrors.slickstack.io/bash/ss-install.txt #####################################
#### path: /var/www/ss-install #####################################################################
#### destination: n/a (not a boilerplate) ##########################################################
#### purpose: Reinstalls the entire SlickStack LEMP environment and all modules (idempotent) #######
#### module version: Ubuntu 20.04 LTS ##############################################################
#### sourced by: n/a (wget -O ss slick.fyi && bash ss) #############################################
#### bash aliases: ss install ######################################################################
####################################################################################################

## SS-CONFIG MUST BE PROPERLY CONFIGURED AND ON CURRENT BUILD BEFORE RUNNING SS-INSTALL ##
## ENSURE YOUR SS-CONFIG BUILD REMAINS CURRENT BY RUNNING SS-UPDATE OCCASIONALLY ##

## include SlickStack configuration (if exists) ##
SS_CONFIG="/var/www/ss-config"
test -f $SS_CONFIG && source $SS_CONFIG

####################################################################################################
#### SS-Functions: Critical Bash Variables #########################################################
####################################################################################################

## SNIPPET: ss-functions, ss-install

## these are kind of like enviroment variables that are used within various ss scripts ##
## we keep these variables together for easy reference and better organization ##

## ss variables ##
# SS_PS1=`PS1="\[\e[1;35m\]\u@$(hostname -f)\e[m\]:\[\e[45m\]\w\[\e[m\]$ "`
SS_LINUX_KERNEL=`uname -a`
SS_OS_VERSION=`lsb_release -ds`
SS_CPU_CORES=`grep -c ^processor /proc/cpuinfo 2>/dev/null || sysctl -n hw.ncpu || echo "$NUMBER_OF_PROCESSORS"`
SS_DISK_FREE=`df -k --output=avail "$PWD" | tail -n1`
# SS_MYSQL_VERSION=`mysqld --version`
# SS_MYSQL_SIZE=`mysql --execute="SELECT table_schema AS "wordpress", SUM(data_length + index_length) / 1024 / 1024 / 1024 AS "Size (GB)" FROM information_schema.TABLES GROUP BY table_schema";`
SS_NETWORK_INTERFACE=`ip route get 1.1.1.1 | head -n1 | awk '{print $5}'`
SS_IPV4_ADDRESS=`ip addr show $SS_NETWORK_INTERFACE | grep "inet " | awk '{ print $2;exit }' | cut -d/ -f1`
SS_IPV6_ADDRESS=`ip addr show $SS_NETWORK_INTERFACE | grep "inet6 " | awk '{ print $2;exit }' | cut -d/ -f1`
SS_HOSTNAME=`hostname -f`
SS_TLD=`hostname -d`
# SS_PHP_VERSION=`php -v | grep ^PHP | cut -d' ' -f2`
# SS_PHP_EXTENSIONS=`php -r "print_r(implode(', ', get_loaded_extensions()));"`

## old ##
UBUNTU_VERSION=`lsb_release -rs`
DISK_FREE=`df -k --output=avail "$PWD" | tail -n1`
NETWORK_INTERFACE=`ip route get 1.1.1.1 | head -n1 | awk '{print $5}'`
IPV4_ADDRESS=`ip addr show $NETWORK_INTERFACE | grep "inet " | awk '{ print $2;exit }' | cut -d/ -f1`
IPV6_ADDRESS=`ip addr show $NETWORK_INTERFACE | grep "inet6 " | awk '{ print $2;exit }' | cut -d/ -f1`

## ss-install-wordpress-config variables ##
TMP_WORDPRESS_CONFIG_PRODUCTION="/tmp/wp-config-production.txt"
TMP_WORDPRESS_CONFIG_STAGING="/tmp/wp-config-staging.txt"
TMP_WORDPRESS_CONFIG_DEV="/tmp/wp-config-dev.txt"

####################################################################################################
#### SS-Functions: Critical Bash Functions #########################################################
####################################################################################################

## SNIPPET: ss-functions, ss-install

## the below functions are sourced into every SlickStack script to ensure reliability ##
## this also speeds up processing times by avoiding repeated inline commands ##

## add-apt-repository alias flags ##
function add-apt-repository {
    export DEBIAN_FRONTEND=noninteractive
    export DEBIAN_PRIORITY=critical
    export PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
    command /usr/bin/add-apt-repository --yes "$@"
}

## apt alias flags ##
function apt {
    export DEBIAN_FRONTEND=noninteractive
    export DEBIAN_PRIORITY=critical
    export PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
    command /usr/bin/apt --yes --quiet --option Dpkg::Options::=--force-confold --option Dpkg::Options::=--force-confdef "$@"
}

## cp alias flags ##
function cp {
    command cp -R -f -d --no-preserve=mode,ownership "$@"
}

## ln alias flags ##
function ln {
    command ln -s -f "$@"
}

## mkdir alias flags ##
function mkdir {
    command mkdir -p "$@"
}

## mysql alias flags ##
function mysql {
    command mysql --user=root --host=localhost --protocol=socket --port=3306 --force "$@"
}

## mysqldump alias flags ##
function mysqldump {
    # /usr/bin/mysqldump
    command mysqldump --user=$DB_USER --password=$DB_PASSWORD --host=$DB_HOST --protocol=tcp --port=3306 --no-tablespaces --single-transaction --skip-lock-tables --dump-date --force "$@"
}

## rm alias flags ##
function rm {
    command rm -R -f "$@"
}

## rsync alias flags ##
function rsync {
    command rsync -aI --ignore-errors "$@"
}

## touch alias flags ##
function touch {
    command touch -a "$@"
}

## unzip alias flags ##
function unzip {
    command unzip -o "$@"
}

## wget alias flags ##
function wget {
    command wget --quiet --no-check-certificate --no-cache --no-cookies --tries=3 --timeout=15 "$@"
}

####################################################################################################
#### SS-Functions: Pretty Colors + Styles For The Shell ############################################
####################################################################################################

## SNIPPET: ss-functions, ss-install

## these color variables help maintain cleaner and prettier Bash scripts in SlickStack ##
## we substitute e.g. ${PINK} within any echo line then use ${RESET} to revert ##

## pretty colors ##
NOCOLOR='\033[0m'
DARKRED='\033[0;31m'
LIGHTRED='\033[1;31m'
ORANGE='\033[0;33m'
YELLOW='\033[1;33m'
DARKGREEN='\033[0;32m'
LIGHTGREEN='\033[1;32m'
DARKCYAN='\033[0;36m'
LIGHTCYAN='\033[1;36m'
DARKBLUE='\033[0;34m'
LIGHTBLUE='\033[1;34m'
DARKPURPLE='\033[0;35m'
LIGHTPURPLE='\033[1;35m'

PURPLE='\033[0;35m'

PINK='\033[1;35m'

DARKGRAY='\033[1;30m'
LIGHTGRAY='\033[0;37m'
WHITE='\033[1;37m'

BGBLACK=$(tput setab 0) # black
BGRED=$(tput setab 1) # red
BGGREEN=$(tput setab 2) # green
BGYELLOW=$(tput setab 3) # yellow
BGBLUE=$(tput setab 4) # blue
BGPINK=$(tput setab 5) # magenta (pink)
BGCYAN=$(tput setab 6) # cyan
BGWHITE=$(tput setab 7) # white

## pretty styles ##
BOLD=$(tput bold) # bold (strong)
DIM=$(tput dim) # dim (half-bright)
NORMAL=$(tput sgr0) # reset all styles (normal)
RESET=$(tput sgr0) # reset all styles (normal)
BLINK=$(tput blink) # blink
UNDERLINE=$(tput smul) # underline
ENDUNDER=$(tput rmul) # end underline
REVERSE=$(tput rev) # reverse
STANDOUT=$(tput smso) # standout (highlight)
ENDSTAND=$(tput rmso) # end standout

####################################################################################################
#### SS-Install: Verify Environment Compatibility Before Proceeding ################################
####################################################################################################

## never run ss-install unless the build version below matches current ss-config version ##
## in case of emergencies the SlickStack team might purposefully mismatch builds ##

## ensure ss-config (if exists) build matches ss-install ##
if [[ -f "/var/www/ss-config" ]] && [[ "$SS_BUILD" != "SEP2021BB" ]]; then 
    echo -e "${YELLOW}Exiting ss-install: Please run ss-update-config since your ss-config is outdated and try again... ${NOCOLOR}"
    exit 1
fi

## verify optimal Ubuntu version ##
if [[ "${UBUNTU_VERSION}" != @(20.04|18.04) ]]; then
    echo -e "${YELLOW}Exiting ss-install: SlickStack is designed for Ubuntu LTS (but this VPS is running ${UBUNTU_VERSION})... ${NOCOLOR}"
    exit 1
fi

## ensure at least 5GB free disk space remains ##
if [[ $DISK_FREE -lt 5242880 ]]; then # 10G = 10485760 / 5GB = 5242880
    echo -e ""
    echo -e "${YELLOW}Exiting ss-install: It looks like your server has less than 5GB free space available, please upgrade your server and then run ss-install again. ${NOCOLOR}"
    echo -e ""
    exit 1
fi

## ensure not running in docker/lxc/container ##
if [[ -f /.dockerenv ]] || grep -Eq '(lxc|docker)' /proc/1/cgroup; then 
    echo -e ""
    echo -e "${YELLOW}Exiting ss-install: It appears your server is running Docker or another container... but SlickStack requires normal Ubuntu LTS without containers. ${NOCOLOR}"
    echo -e ""
    exit 1
fi

####################################################################################################
#### SS-Update: Ensure Undefined Options Do Not Exist Before Proceeding ############################
####################################################################################################

## SNIPPET: ss-install, ss-update

## below snippet will warn you and exit if undefined ss-config options are found to exist ##
## this way our team can be aware of bugs and avoid implementing unwanted options ##

## warn if placeholders exist ##
SS_CONFIG_OPTION_PLACEHOLDER="$(grep -c '"@' /var/www/ss-config)"
if [[ "$SS_CONFIG_OPTION_PLACEHOLDER" -gt 0 ]]; then
    echo -e "${LIGHTRED}Exiting ss-install: Your ss-config contains "@..." placeholders. Please input values and try again... ${NOCOLOR}"
    exit 1
fi

####################################################################################################
#### SS-Install: Cleanup Temporary Files ###########################################################
####################################################################################################

## delete tmp files ##
rm /tmp/ss-config*
rm /tmp/config*

####################################################################################################
#### SS-Install: Interactive Bash Setup Wizard (Generate SS-Config) ################################
####################################################################################################

## this basic wizard will allow you to interactively setup your ss-config file options ##
## advanced users can setup ss-config before running ss-install to avoid this ##

## retrieve latest ss-config boilerplate (quietly) ##
wget -qO /tmp/ss-config https://raw.githubusercontent.com/littlebizzy/slickstack/master/bash/ss-config-sample.txt
    
## check build ver ##
SS_BUILD_NOW=$(source /tmp/ss-config; echo $SS_BUILD)

## rainbow colors test ##
WELCOME_RAINBOW="${DARKRED}welcome ${LIGHTRED}to ${ORANGE}the ${YELLOW}magical ${DARKGREEN}world ${LIGHTGREEN}of ${DARKCYAN}ss ${LIGHTCYAN}where ${DARKBLUE}all ${LIGHTBLUE}your ${DARKPURPLE}dreams ${LIGHTPURPLE}come ${LIGHTGRAY}true${NOCOLOR}"
echo -e ""
echo -e "$WELCOME_RAINBOW"

## f*ck containers (first things first) ##
echo -e ""
echo -e "${LIGHTPURPLE} _____________________________ ${NOCOLOR}"
echo -e "${LIGHTPURPLE}< screw containers! excelsior > ${NOCOLOR}"
echo -e "${LIGHTPURPLE} ----------------------------- ${NOCOLOR}"
echo -e "${LIGHTPURPLE}        \   ^__^ ${NOCOLOR}"
echo -e "${LIGHTPURPLE}         \  (oo)\_______ ${NOCOLOR}"
echo -e "${LIGHTPURPLE}            (__)\       )\/\ ${NOCOLOR}"
echo -e "${LIGHTPURPLE}                ||----w | ${NOCOLOR}"
echo -e "${LIGHTPURPLE}                ||     || ${NOCOLOR}"
echo -e ""
echo -e ""

if [[ ! -f "/var/www/ss-config" ]]; then
    echo -e "${LIGHTGRAY}################################################################################${NOCOLOR}"
    echo -e "${LIGHTGRAY}SlickStack build   :  ${LIGHTGREEN}$SS_BUILD_NOW${NOCOLOR}"
    echo -e "${LIGHTGRAY}Ubuntu version     :  ${LIGHTGREEN}${UBUNTU_VERSION} LTS${NOCOLOR}"
    echo -e "${LIGHTGRAY}Hostname (FQDN)    :  ${LIGHTGREEN}$SS_HOSTNAME${NOCOLOR}"
    echo -e "${LIGHTGRAY}IP Address (IPv4)  :  ${LIGHTGREEN}$SS_IPV4_ADDRESS${NOCOLOR}"
    echo -e "${LIGHTGRAY}IP Address (IPv6)  :  ${LIGHTGREEN}$SS_IPV6_ADDRESS${NOCOLOR}"
    echo -e "${LIGHTGRAY}################################################################################${NOCOLOR}"
    echo -e ""
    echo -e "${YELLOW}Welcome to SlickStack! It appears that your ss-config file has not been ${NOCOLOR}"
    echo -e "${YELLOW}setup yet. Please use the wizard to configure required options, or hit ${NOCOLOR}"
  
    wait_time=30 # seconds
    temp_cnt=${wait_time}
    while [[ ${temp_cnt} -gt 0 ]];
    do
        printf "${YELLOW}\rCtrl+C to cancel wizard and configure ss-config manually: ${LIGHTGREEN}%2d ${NOCOLOR}" ${temp_cnt}
        sleep 1
        ((temp_cnt--))
    done
    echo -e ""
    echo -e ""
    echo -e "${LIGHTPURPLE}###########################################################################${NOCOLOR}"
    echo -e "${LIGHTPURPLE}#### SlickStack Interactive Setup Wizard (SS-Config) ######################${NOCOLOR}"
    echo -e "${LIGHTPURPLE}###########################################################################${NOCOLOR}"
    echo -e ""
    
    ## replace root password fields with random strings ##
    sed -i "s/@ROOT_PASSWORD/$(openssl rand -hex 12)/g" /tmp/ss-config
    sed -i "s/@DB_PASSWORD_ROOT/$(openssl rand -hex 12)/g" /tmp/ss-config
    
    ## PROMPT: choose sudo username (default = batman) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose sudo username (for SSH): "$NORMAL)" -e -i 'batman' ss_var_sudo_user || ss_var_sudo_user=batman
    sed -i "s/@SUDO_USER/$ss_var_sudo_user/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose sudo password (default = random) ##
    sudopass_random=$(openssl rand -hex 12)
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose sudo password (should be strong): "$NORMAL)" -e -i ${sudopass_random} ss_var_sudo_password || ss_var_sudo_password=${sudopass_random}
    sed -i "s/@SUDO_PASSWORD/$ss_var_sudo_password/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose SSH port number (default = 22) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose SSH port (use 22 for best compatibility): "$NORMAL)" -e -i '22' ss_var_ssh_port || ss_var_ssh_port=22
    sed -i "s/@SSH_PORT/$ss_var_ssh_port/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: enable SSH keys (default = false) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Enable SSH keys (advanced users only): "$NORMAL)" -e -i 'false' ss_var_ssh_keys || ss_var_ssh_keys=false
    sed -i "s/@SSH_KEYS/$ss_var_ssh_keys/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose SFTP username (default = robin) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose SFTP username (limited access): "$NORMAL)" -e -i 'robin' ss_var_sftp_user || ss_var_sftp_user=robin
    sed -i "s/@SFTP_USER/$ss_var_sftp_user/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose SFTP password (default = random) ##
    sftp_pass_random=$(openssl rand -hex 12)
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose SFTP password (should be strong): "$NORMAL)" -e -i ${sftp_pass_random} ss_var_sftp_password || ss_var_sftp_password=${sftp_pass_random}
    sed -i "s/@SFTP_PASSWORD/$ss_var_sftp_password/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose app (default = wordpress) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose app (only wordpress supported currently): "$NORMAL)" -e -i 'wordpress' ss_var_app_name || ss_var_app_name=wordpress
    sed -i "s/@SS_APP/$ss_var_app_name/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: enable plugin blacklist (default = true) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Enable the WordPress plugin blacklist: "$NORMAL)" -e -i 'true' ss_var_plugin_blacklist || ss_var_plugin_blacklist=true
    sed -i "s/@SS_WORDPRESS_PLUGIN_BLACKLIST/$ss_var_plugin_blacklist/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: link your pilot file (default = blank) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Link to your pilot file (leave blank if none): "$NORMAL)" -e -i 'https://gist.githubusercontent.com/...' ss_var_pilot_file || ss_var_pilot_file=
    sed -i "s/@SS_PILOT_FILE/$ss_var_pilot_file/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: using a remote database (default = wordpress) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Are you using a remote database: "$NORMAL)" -e -i 'false' ss_var_database_remote || ss_var_database_remote=false
    sed -i "s/@SS_DATABASE_REMOTE/$ss_var_database_remote/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose database name (default = production) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose database name (single database): "$NORMAL)" -e -i 'production' ss_var_db_name || ss_var_db_name=production
    sed -i "s/@DB_NAME/$ss_var_db_name/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose database user (default = robin) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose database user (non-root user): "$NORMAL)" -e -i 'robin' ss_var_db_user || ss_var_db_user=robin
    sed -i "s/@DB_USER/$ss_var_db_user/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose database user password (default = random) ##
    db_pass_random=$(openssl rand -hex 12)
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose database user password (should be strong): "$NORMAL)" -e -i ${db_pass_random} ss_var_db_password || ss_var_db_password=${db_pass_random}
    sed -i "s/@DB_PASSWORD_USER/$ss_var_db_password/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose database host ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose database host (IP address): "$NORMAL)" -e -i '127.0.0.1' ss_var_db_host || ss_var_db_host=127.0.0.1
    sed -i "s/@DB_HOST/$ss_var_db_host/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose database prefix ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose database table prefix: "$NORMAL)" -e -i 'wp_' ss_var_db_prefix || ss_var_db_prefix=wp_
    sed -i "s/@DB_PREFIX/$ss_var_db_prefix/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose site TLD (otherwise example.com) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose site TLD (subdomains not allowed): "$NORMAL)" -e -i "$SS_TLD" ss_var_site_tld || ss_var_site_tld="$SS_TLD"
    sed -i "s/@SITE_TLD/$ss_var_site_tld/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose site domain (otherwise www.example.com) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose site domain (subdirectories not allowed): "$NORMAL)" -e -i "$SS_HOSTNAME" ss_var_site_domain || ss_var_site_domain="$SS_HOSTNAME"
    sed -i "s/@SITE_DOMAIN/$ss_var_site_domain/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: enable noindex server (default = false) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Enable site noindexing (block robots): "$NORMAL)" -e -i 'false' ss_var_site_noindex || ss_var_site_noindex=false
    sed -i "s/@SITE_NOINDEX/$ss_var_site_noindex/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: which SSL do you want ##
    read -t 300 -p "$(echo -e $PINK"Choose SSL cert [openssl|certbot]: "$NORMAL)" -e -i 'openssl' ss_var_ssl_type || ss_var_ssl_type=openssl
    sed -i "s/@SSL_TYPE/$ss_var_ssl_type/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## Multisite not supported yet ##
    ## PROMPT: enable WP multisite (otherwise disabled) ##
    # read -p 'Enable WP multisite (no): ' ss_var_wp_multisite
    
    ## PROMPT: disable WP multisite subdomains (otherwise enabled) ##
    # read -p 'Enable WP multisite subdomains (yes): ' ss_var_wp_multisite_subdomains
    
    ## PROMPT: enable WP multisite domain mapping (otherwise disabled) ##
    # read -p 'Enable WP multisite domain mapping (no): ' ss_var_wp_multisite_domain_mapping
    
    ## PROMPT: choose Cloudflare API key (otherwise 123456789) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose Cloudflare API key (account profile): "$NORMAL)" -e -i '123456789' ss_var_cloudflare_api_key || ss_var_cloudflare_api_key=123456789
    sed -i "s/@CLOUDFLARE_API_KEY/$ss_var_cloudflare_api_key/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose Cloudflare API email (otherwise user@example.com) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose Cloudflare API email (account profile): "$NORMAL)" -e -i 'user@example.com' ss_var_cloudflare_api_email || ss_var_cloudflare_api_email=user@example.com
    sed -i "s/@CLOUDFLARE_API_EMAIL/$ss_var_cloudflare_api_email/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: enable staging site ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Enable staging site (subdomain): "$NORMAL)" -e -i 'false' ss_var_staging_site || ss_var_staging_site=false
    sed -i "s/@STAGING_SITE_STATUS/$ss_var_staging_site/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: protect staging site ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Password protect staging site: "$NORMAL)" -e -i 'false' ss_var_staging_site_protect || ss_var_staging_site_protect=false
    sed -i "s/@STAGING_SITE_PROTECT/$ss_var_staging_site_protect/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: enable dev site ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Enable dev site (subdomain): "$NORMAL)" -e -i 'false' ss_var_dev_site || ss_var_dev_site=false
    sed -i "s/@DEV_SITE_STATUS/$ss_var_dev_site/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: protect dev site ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Password protect dev site: "$NORMAL)" -e -i 'false' ss_var_dev_site_protect || ss_var_dev_site_protect=false
    sed -i "s/@DEV_SITE_PROTECT/$ss_var_dev_site_protect/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose guest username (default = guest) ##
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose guest username (to view staging/dev): "$NORMAL)" -e -i 'guest' ss_var_guest_user || ss_var_guest_user=guest
    sed -i "s/@GUEST_USER/$ss_var_guest_user/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## PROMPT: choose guest password (default = random) ##
    guest_pass_random=$(openssl rand -hex 12)
    read -t 300 -p "$(echo -e $LIGHTPURPLE"Choose guest password (easy is fine): "$NORMAL)" -e -i ${guest_pass_random} ss_var_guest_password || ss_var_guest_password=${guest_pass_random}
    sed -i "s/@GUEST_PASSWORD/$ss_var_guest_password/g" /tmp/ss-config
    
    ## new line ##
    printf "\n"
    
    ## copy files to their destinations ##
    mkdir /var/www
    cp /tmp/ss-config /var/www/ss-config
    
####################################################################################################
#### SS-Install: Message (Last Chance To Exit) #####################################################
####################################################################################################

## this is a simple message that announces to the shell the purpose of this bash script ##
## it will only be noticed by sudo users who manually call ss core bash scripts ##

## force exit if SSH keys chosen ##
SSHKEYS_CHOSEN=$(source /var/www/ss-config; echo $SSH_KEYS)
if [[ "$SSHKEYS_CHOSEN" == "true" ]] && [[ ! -f "/var/www/auth/id_rsa.pub" ]]; then
    echo -e "${YELLOW}Exiting ss-install: Please upload your /var/www/auth/id_rsa.pub file before proceeding... ${NOCOLOR}"
    echo -e "${YELLOW}Alternatively SlickStack will create a new key pair for you (just run ss-install again now)... ${NOCOLOR}"
fi

## force exit if thirdparty SSL chosen ##
THIRDPARTY_CHOSEN=$(source /var/www/ss-config; echo $SSL_TYPE)
if [[ "$THIRDPARTY_CHOSEN" == "thirdparty" ]] && [[ ! -f "/var/www/certs/thirdparty.pem" || ! -f "/var/www/certs/keys/thirdparty.key" ]]; then
    echo -e "${YELLOW}Exiting ss-install: Since you chose thirdparty SSL please upload your cert/key before proceeding... ${NOCOLOR}"
fi

    ## echo message ##
    echo -e "${YELLOW}Your /var/www/ss-config file is now setup, yay! Ctrl+C to exit now if you  ${NOCOLOR}"

    WAIT_TIME_LAST_CHANCE="15" # seconds
    WAIT_TIME_LAST_CHANCE_TMP="${WAIT_TIME_LAST_CHANCE}"
    while [[ ${WAIT_TIME_LAST_CHANCE_TMP} -gt 0 ]];
    do
        printf "${YELLOW}\rwant to review all options before proceeding, otherwise wait... ${LIGHTGREEN}%2d ${NOCOLOR}" ${WAIT_TIME_LAST_CHANCE_TMP}
        sleep 1
        ((WAIT_TIME_LAST_CHANCE_TMP--))
    done

    echo -e ""
    
####################################################################################################
#### SS-Install: Welcome Back (If SS-Config Exists) ################################################
####################################################################################################

else
    echo -e "${LIGHTGRAY}################################################################################${NOCOLOR}"
    echo -e "${LIGHTGRAY}SlickStack build   :  ${LIGHTGREEN}$SS_BUILD_NOW${NOCOLOR}"
    echo -e "${LIGHTGRAY}Ubuntu version     :  ${LIGHTGREEN}${UBUNTU_VERSION} LTS${NOCOLOR}"
    echo -e "${LIGHTGRAY}Hostname (FQDN)    :  ${LIGHTGREEN}$SS_HOSTNAME${NOCOLOR}"
    echo -e "${LIGHTGRAY}IP Address (IPv4)  :  ${LIGHTGREEN}$SS_IPV4_ADDRESS${NOCOLOR}"
    echo -e "${LIGHTGRAY}IP Address (IPv6)  :  ${LIGHTGREEN}$SS_IPV6_ADDRESS${NOCOLOR}"
    echo -e "${LIGHTGRAY}################################################################################${NOCOLOR}"
    echo -e ""
    echo -e "${PURPLE}Running ss-install: An ss-config file already exists so we will proceed using existing settings... ${NOCOLOR}"
    sleep 10s
fi

####################################################################################################
#### SS-Install: Source SS-Config (After Setup Wizard Complete) ####################################
####################################################################################################

## here we must source ss-config again after the setup wizard has completed generation ##
## this is different than the conditional sourcing at the top of this script ##

## include SlickStack configuration ##
source /var/www/ss-config

####################################################################################################
#### SS-Install: Ensure Chosen Site Domain Is Not Sub-Subdomain (Unsupported) ######################
####################################################################################################

## for compatibility and stability reasons SlickStack does not support sub-subdomains ##
## this ensures that your SSL and Cloudflare especially will function properly ##

## calculate how many dots in chosen site domain ##
CALC_DOMAIN=${SITE_DOMAIN//$SITE_TLD/}
CALC_DOMAIN_SUB=$(echo "$CALC_DOMAIN" | grep -o "\." | wc -l)

## exit if the local domain (besides TLD) contains more than one dot ##
if [[ $CALC_DOMAIN_SUB -gt 1 ]]; then 
    echo -e ""
    echo -e "${YELLOW}It appears your SITE_DOMAIN value is a sub-subdomain or is otherwise not ${NOCOLOR}"
    echo -e "${YELLOW}compatible with SlickStack. Please edit ss-config and try again. ${NOCOLOR}"
    echo -e ""
    exit 1
fi

####################################################################################################
#### SS-Install: Retrieve Latest SS Core Cron Jobs + SS Core Bash Scripts ##########################
####################################################################################################

## now that ss-config is ready we must retrieve the latest core cron jobs and scripts ##


## download latest versions ##
wget -O /tmp/ss-functions https://raw.githubusercontent.com/littlebizzy/slickstack/master/bash/ss-functions.txt

wget -O /tmp/ss-check https://raw.githubusercontent.com/littlebizzy/slickstack/master/bash/ss-check.txt

## copy files to their destinations ##
cp /tmp/ss-functions /var/www/ss-functions
cp /tmp/ss-check /var/www/ss-check

## reset permissions ##
chown root:root /var/www/ss* ## must be root:root
chmod 0700 /var/www/ss* ## 0700 means root can execute

## run scripts ##
source /var/www/ss-check


source /var/www/ss-functions

####################################################################################################
#### SS-Install: Set Confold As Ubuntu Dpkg Default ################################################
####################################################################################################

## the first time you run ss-install we want to ensure that confold is dpkg default ##
## this helps to avoid overwriting module config files that SlickStack uses ##

## set confold as dpkg default (fail-safe in case apt upgrade called directly) ##
DEBIAN_FRONTEND=noninteractive dpkg --configure -a --force-confold

## update Ubuntu repo cache ##
apt update

## upgrade installed Ubuntu packages (LEMP modules) + but now Linux kernel (full-upgrade) ##
apt upgrade

####################################################################################################
#### SS-Install: Configure Ubuntu ##################################################################
####################################################################################################

## first we need to setup all users and passwords for Ubuntu and set sudo permissions ##
## this process will also set the default SSH port and disable root logins ##

## run ss-install-ubuntu-users ##
source "$PATH_SS_INSTALL_UBUNTU_USERS"

## SlickStack aims to emphasize traditional bash scripts but we still support aliases ##
## in most cases using aliases are not necessary but can help you save time ##

## run ss-install-ubuntu-bash ##
source "$PATH_SS_INSTALL_UBUNTU_BASH"

## run ss-install-ubuntu-ssh ##
source "$PATH_SS_INSTALL_UBUNTU_SSH"

## cron should be installed by default on Ubuntu but this script will install otherwise ##
## it will also install a crontab file and cron jobs from SlickStack mirrors ##

## run ss-install-ubuntu-crontab ##
source "$PATH_SS_INSTALL_UBUNTU_CRONTAB"

## run ss-install-ubuntu-swapfile ##
source "$PATH_SS_INSTALL_UBUNTU_SWAPFILE"

## run ss-install-ubuntu-utils ##
source "$PATH_SS_INSTALL_UBUNTU_UTILS"

## we save this for near last just in case the kernel gets messed up and requires fixing ##
## in SlickStack the kernel is modified to pretty much uncap all limitations ##

## run ss-install-ubuntu-kernel ##
source "$PATH_SS_INSTALL_UBUNTU_KERNEL"

####################################################################################################
#### SS-Install: Install PHP-FPM ###################################################################
####################################################################################################

## here we install the PHP-FPM module which includes OPcache for better performance ##
## FastCGI is configured to interface with Nginx using TCP (127.0.0.1:9000) ##

if [[ "$SS_APP" != "mysql" ]]; then

    ## run ss-install-php-packages ##
    source "$PATH_SS_INSTALL_PHP_PACKAGES"

    ## run ss-install-php-config ##
    source "$PATH_SS_INSTALL_PHP_CONFIG"

fi

####################################################################################################
#### SS-Install: Install Nginx + SSL Certificates ##################################################
####################################################################################################

## the Nginx installer includes OpenSSL and Lets Encrypt generation to avoid conflicts ##
## default settings allow for very high-traffic so CloudFlare is recommended ##

if [[ "$SS_APP" != "mysql" ]]; then

    ## run ss-install-nginx-packages ##
    source "$PATH_SS_INSTALL_NGINX_PACKAGES"

    ## run ss-install-nginx-config ##
    source "$PATH_SS_INSTALL_NGINX_CONFIG"

    ## run ss-install-nginx-ssl ##
    # source "$PATH_SS_INSTALL_NGINX_SSL"

fi

####################################################################################################
#### SS-Install: Enable Maintenance Mode ###########################################################
####################################################################################################

## this is a nifty snippet that will put up a public maintenance page during install ##
## it helps prevent users from interacting with your website at this stage ##

if [[ "$SS_APP" != "mysql" ]]; then

    ## run ss-maintenance-enable ##
    source "$PATH_SS_MAINTENANCE_ENABLE"

fi

####################################################################################################
#### SS-Install: Install MySQL #####################################################################
####################################################################################################

## here we install MySQL server (no client) and users based on the ss-config settings ##
## root@localhost will use sockets and PHP apps will connect via 127.0.0.1 ##

## run ss-install-mysql-packages ##
source "$PATH_SS_INSTALL_MYSQL_PACKAGES"

## run ss-install-mysql-config ##
source "$PATH_SS_INSTALL_MYSQL_CONFIG"

## run ss-install-mysql-database ##
# source "$PATH_SS_INSTALL_MYSQL_DATABASE"

####################################################################################################
#### SS-Install: Install Redis #####################################################################
####################################################################################################

## Redis is only installed to enable object caching in WordPress (if plugin exists) ##
## full page caching is provided solely by Nginx FastCGI and not by Redis ##

if [[ "$SS_APP" != "mysql" ]]; then

    ## run ss-install-redis-packages ##
    source "$PATH_SS_INSTALL_REDIS_PACKAGES"

    ## run ss-install-redis-config ##
    source "$PATH_SS_INSTALL_REDIS_CONFIG"

fi

####################################################################################################
#### SS-Install: Install Adminer ###################################################################
####################################################################################################

## should be installed after PHP-FPM and Nginx modules to ensure seamless installation ##
## Adminer (similar to phpMyAdmin) can be publicly accessed at /adminer URI ##

## run ss-install-adminer ##
source "$PATH_SS_INSTALL_ADMINER"
 
####################################################################################################
#### SS-Install: Install CMS (WordPress, PrestaShop, MediaWiki, Etc) ###############################
####################################################################################################

## SNIPPET: ss-install, ss-update

## this snippet fetches the latest stable version of WordPress from SlickStack mirrors ##
## major CMS releases (unpatched) are never considered stable for our purposes ##
    
if [[ "$SS_APP" == "wordpress" || -z "$SS_APP"  ]]; then

    ## run ss-install-wordpress-core ##
    source "$PATH_SS_INSTALL_WORDPRESS_CORE"

    ## here we retrieve latest wp-config.php boilerplate and customize per ss-config settings ##
    ## you should never make changes directly to wp-config.php in SlickStack servers ##

    ## run ss-install-wordpress-config ##
    source "$PATH_SS_INSTALL_WORDPRESS_CONFIG"

    ## this will install the designated MU plugins and also Custom Functions and Object Cache ##
    ## with a few exceptions these can all be customized using ss-config settings ##

    ## run ss-install-wordpress-mu-plugins ##
    source "$PATH_SS_INSTALL_WORDPRESS_MU_PLUGINS"
    
    ## run ss-install-wordpress-cli ##
    source "$PATH_SS_INSTALL_WORDPRESS_CLI"

fi

## this snippet fetches the latest stable version of PrestaShop from SlickStack mirrors ##
## major CMS releases (unpatched) are never considered stable for our purposes ##

if [[ "$SS_APP" == "prestashop" ]]; then

    ## run ss-install-prestashop-core ##
    source "$PATH_SS_INSTALL_PRESTASHOP_CORE"
    
    ## run ss-install-prestashop-config ##
    source "$PATH_SS_INSTALL_PRESTASHOP_CONFIG"
    
fi

## this snippet fetches the latest stable version of MediaWiki from SlickStack mirrors ##
## major CMS releases (unpatched) are never considered stable for our purposes ##

if [[ "$SS_APP" == "mediawiki" ]]; then

    ## run ss-install-prestashop-core ##
    source "$PATH_SS_INSTALL_MEDIAWIKI_CORE"
    
    ## run ss-install-prestashop-config ##
    source "$PATH_SS_INSTALL_MEDIAWIKI_CONFIG"
    
fi

####################################################################################################
#### SS-Install: Install Rclone ########################################################
####################################################################################################

## run ss-install-rclone-packages ##
source "$PATH_SS_INSTALL_RCLONE_PACKAGES"

## run ss-install-rclone-config ##
source "$PATH_SS_INSTALL_RCLONE_CONFIG"

####################################################################################################
#### SS-Install: Install ClamAV ####################################################################
####################################################################################################

## this will install ClamAV for occassional malware logging: /var/www/logs/clamav.log ##
## keep in mind that infected files are not automatically cleaned or deleted ##

## run ss-install-clamav ##
source "$PATH_SS_INSTALL_CLAMAV"

####################################################################################################
#### SS-Install: Install UFW Firewall ##############################################################
####################################################################################################

## here we install and configure the very simple UFW Firewall that Ubuntu maintains ##
## only ports 80, 443, and your designated SSH port (22) will be allowed ##

## run ss-install-ufw-packages ##
source "$PATH_SS_INSTALL_UFW_PACKAGES"

## run ss-install-ufw-config ##
source "$PATH_SS_INSTALL_UFW_CONFIG"

####################################################################################################
#### SS-Install: Reset All Logs To NULL ############################################################
####################################################################################################

## run ss-empty-logs ##
source "$PATH_SS_EMPTY_LOGS"

####################################################################################################
#### SS-Install: Reset Permissions (All Permissions) ###############################################
####################################################################################################

## intuitively resets all file and user permissions across the entire SlickStack server ##
## depending on the CMS installed it will also reset those permissions as well ##

## run ss-perms ##
source "$PATH_SS_PERMS"

####################################################################################################
#### SS-Install: Disable Maintenance Mode ##########################################################
####################################################################################################

## run ss-maintenance-disable ##
source "$PATH_SS_MAINTENANCE_DISABLE"

####################################################################################################
#### SS-Install: Clear Caches (All Caches) #########################################################
####################################################################################################

## this clears all caches i.e. Nginx, OPcache, Redis object cache, and WP transients ##
## we run this after ss-perms and before ss-restart-modules to avoid conflicts ##

if [[ "$SS_APP" != "mysql" ]]; then

    ## run ss-purge-nginx ##
    source "$PATH_SS_PURGE_NGINX"

    ## run ss-purge-opcache ##
    source "$PATH_SS_PURGE_OPCACHE"

    ## run ss-purge-redis ##
    source "$PATH_SS_PURGE_REDIS"

    ## run ss-purge-transients ##
    source "$PATH_SS_PURGE_TRANSIENTS"

fi

####################################################################################################
#### SS-Install: Restart Modules (All Modules) #####################################################
####################################################################################################

## this script is using init.d instead of systemd shortcuts to allow for absolute paths ##
## we are looking into including other snippets here such as unmasking (etc) ##

if [[ "$SS_APP" != "mysql" ]]; then

    ## run ss-restart-php ##
    source "$PATH_SS_RESTART_PHP"

    ## run ss-restart-nginx ##
    source "$PATH_SS_RESTART_NGINX"

    ## run ss-restart-redis ##
    source "$PATH_SS_RESTART_REDIS"

fi

## run ss-restart-mysql ##
source "$PATH_SS_RESTART_MYSQL"

## run ss-restart-ufw ##
source "$PATH_SS_RESTART_UFW"

####################################################################################################
#### SS-Install: Run SS-Worker #########################################
####################################################################################################

## just in case any random things need to be done ##

## run ss-worker ##
source "$PATH_SS_WORKER"


####################################################################################################
#### SS-Install: Validate Crontab ##################################################################
####################################################################################################

## this is a final check to ensure the root crontab was installed properly by ss-install ##
## otherwise it will attempt to reinstall the crontab one more time here ##

## validate crontab ##
VALIDATE_CRONTAB=$(grep 'SS_EOF' /var/spool/cron/crontabs/root)
if [[ -z "$VALIDATE_CRONTAB" ]]; then
    source "$PATH_SS_INSTALL_UBUNTU_CRONTAB"
fi

####################################################################################################
#### SS-Install: Display SlickStack Configuration Overview #########################################
####################################################################################################

## the shell will echo the most important ss-config settings (and beyond) currently used ##
## this allows you to easily copy/paste for your records or for your clients ##

## run ss-stack-overview ##
source "$PATH_SS_STACK_OVERVIEW"

####################################################################################################
#### SS-Install: MESSAGE (End) #####################################################################
####################################################################################################

if [[ "$SSH_KEYS" == "true" ]]; then 
    echo -e ""
    echo -e "${YELLOW}Since you enabled SSH keys be sure to add your public key to: ${PATH_SSH_AUTHORIZED_KEYS_FILE}${NOCOLOR}"
    echo -e "${YELLOW}...or simply use the default public key if you prefer (we added it already).${NOCOLOR}"
    echo -e ""
fi
    
## confirm installation complete ##
echo -e ""
echo -e "${YELLOW}SlickStack install complete! Please note the sudo user and password above ${NOCOLOR}"
echo -e "${YELLOW}to avoid being locked out of your new server (the root user is disabled). ${NOCOLOR}"
echo -e "${YELLOW}Also, be sure to enable [Full SSL] mode in CloudFlare to avoid redirect ${NOCOLOR}"
echo -e "${YELLOW}loops (we do not recommend enabling HSTS, however). For an extra boost, ${NOCOLOR}"
echo -e "${YELLOW}use CloudFlare Page Rules to [cache all] for /wp-content/* requests, and ${NOCOLOR}"
echo -e "${YELLOW}to force-redirect (non)www domain requests too. Lastly be sure to set TLS ${NOCOLOR}"
echo -e "${YELLOW}version to 1.2+ in Cloudflare for top SSL Labs score. Cheers! ${NOCOLOR}"
echo -e ""

####################################################################################################
#### SS-Install: Cleanup Temporary Files ###########################################################
####################################################################################################

## delete tmp files ##
rm /tmp/config
rm /tmp/ss

####################################################################################################
#### SS-Install: Touch Timestamp File (End Script) #################################################
####################################################################################################

## this is a dummy timestamp file that will remember the last time this script was run ##
## it can be useful for developer reference and is sometimes used by SlickStack ##

## script timestamp ##
touch "$TIMESTAMP_SS_INSTALL"

####################################################################################################
#### SlickStack: External References Used To Improve This Script (Thanks, Interwebz) ###############
####################################################################################################

## Ref: http://wproller.com ##
## Ref: https://github.com/bjornjohansen/deploy-wp-on-vps/blob/master/deploy.sh ##
## Ref: https://github.com/sm0k3net/Useful-Scripts/blob/master/wordpress.sh ##
## Ref: https://github.com/techandme/wordpress-vm ##
## Ref: https://github.com/QROkes/webinoly ##
## Ref: https://github.com/WordOps/WordOps ##
## Ref: https://www.isicca.com/en/lemp-howto-install-nginx-php7-mariadb/ ##
## Ref: https://gist.github.com/FeChagas/54b0cdf354b197dc8e417357d7687e8b ##
## Ref: https://github.com/GeekPress/WP-Quick-Install ##
## Ref: https://github.com/bajpangosh/High-Traffic-wordpress-server-configuration ##
## Ref: https://gist.github.com/nickfox-taterli/2c283d73ba817392fb0f9f15d9cfa514 ##
## Ref: https://gist.github.com/beardedinbinary/79d7ad34f9980f0a4c23 ##
## Ref: https://www.linuxbabe.com/security/letsencrypt-webroot-tls-certificate
## Ref: https://stackoverflow.com/questions/49668542/create-a-script-that-adds-lines-of-code-to-bashrc-then-reloads-the-terminal
## Ref: https://peteris.rocks/blog/unattended-installation-of-wordpress-on-ubuntu-server/
## Ref: https://serverfault.com/questions/783527/non-interactive-silent-install-of-mysql-5-7-on-ubuntu-16-04-lts/830352#830352
## Ref: https://www.percona.com/blog/2016/10/18/upgrading-to-mysql-5-7-beware-of-the-new-strict-mode/
## Ref: https://stackoverflow.com/questions/3601515/how-to-check-if-a-variable-is-set-in-bash
## Ref: https://serverfault.com/questions/773964/calculating-the-percentage-of-the-total-available-memory-on-linux-as-an-integer
## Ref: https://stackoverflow.com/questions/29271593/bash-check-for-amount-of-memory-installed-on-a-system-as-sanity-check
## Ref: https://stackoverflow.com/questions/50177216/how-to-grant-all-privileges-to-root-user-in-mysql-8-0
## Ref: https://stackoverflow.com/questions/28118296/bash-script-is-super-slow
## Ref: https://stackoverflow.com/questions/15445361/speeding-up-bash-scripts
## Ref: https://unix.stackexchange.com/questions/67057/bash-script-optimization-of-processing-speed
## Ref: https://unix.stackexchange.com/questions/313256/why-write-an-entire-bash-script-in-functions
## Ref: http://nginx.org/en/linux_packages.html
## Ref: https://www.digitalocean.com/community/questions/nginx-stable-or-mainline-for-production-server
## Ref: https://precisionsec.com/changing-the-wordpress-site-url-using-the-mysql-command-line/
## Ref: https://magc.co/box/notes/change-wp-urls-mysql/
## Ref: https://wordpress.stackexchange.com/questions/281814/wordpress-multisite-redirecting-to-wp-signup-php
## Ref: https://wordpress.stackexchange.com/questions/165507/site-redirecting-to-wp-signup-php
## Ref: https://askubuntu.com/questions/86849/how-to-unzip-a-zip-file-from-the-terminal
## Ref: https://www.computerhope.com/unix/rsync.htm
## Ref: https://lowendbox.com/blog/wordpress-cheap-vps-lowendscript/
## Ref: https://unix.stackexchange.com/questions/67057/bash-script-optimization-of-processing-speed
## Ref: http://www.los-gatos.ca.us/davidbu/faster_sh.html
## Ref: https://blog.eduonix.com/shell-scripting/learn-how-to-write-interactive-shell-scripts/
## Ref: https://www.stefanjudis.com/today-i-learned/how-to-add-interactive-questions-to-bash-scripts/
## Ref: https://askubuntu.com/questions/998640/bash-interactive-script
## Ref: https://ryanstutorials.net/bash-scripting-tutorial/bash-input.php
## Ref: http://www.linfo.org/clear.html
## Ref: https://gist.github.com/jonsuh/3c89c004888dfc7352be
## Ref: https://stackoverflow.com/questions/2924697/how-does-one-output-bold-text-in-bash/2924755
## Ref: https://medium.com/@jasonrigden/cowsay-is-the-most-important-unix-like-command-ever-35abdbc22b7f
## Ref: https://stackoverflow.com/questions/37052899/what-is-the-preferred-method-to-echo-a-blank-line-in-a-shell-script
## Ref: https://tldp.org/LDP/abs/html/options.html
## Ref: https://fernandobasso.dev/shell/shell-script-input-default-values.html
## Ref: https://stackoverflow.com/questions/10735574/include-source-script-if-it-exists-in-bash
## Ref: https://scripter.co/count-down-timer-in-shell/
## Ref: https://stackoverflow.com/questions/4332478/read-the-current-text-color-in-a-xterm/4332530#4332530
## Ref: https://stackoverflow.com/questions/24998434/read-command-display-the-prompt-in-color-or-enable-interpretation-of-backslas
## Ref: https://stackoverflow.com/questions/714915/using-the-passwd-command-from-within-a-shell-script/715802#comment52196688_19745733
## Ref: https://askubuntu.com/questions/1214103/how-to-automate-changing-old-password
## Ref: https://unix.stackexchange.com/questions/223965/i-cant-change-users-passwd-on-ubuntu
## Ref: https://www.tecmint.com/fix-passwd-authentication-token-manipulation-error-in-linux/
## Ref: https://stackoverflow.com/questions/4332478/read-the-current-text-color-in-a-xterm/4332530#4332530
## Ref: https://medium.com/@smohajer85/bash-scripting-tutorial-part-11-8ce0c17b01c1
## Ref: https://linuxhint.com/tput-printf-and-shell-expansions-how-to-create-awesome-outputs-with-bash-scripts/
## Ref: https://stackoverflow.com/questions/8467424/echo-newline-in-bash-prints-literal-n
## Ref: https://askubuntu.com/questions/420784/what-do-the-disabled-login-and-gecos-options-of-adduser-command-stand
## Ref: https://stackoverflow.com/questions/55822739/does-echo-userpass-usr-sbin-chpasswd-override-the-root-password
## Ref: https://stackoverflow.com/questions/8110530/check-free-disk-space-for-current-partition-in-bash
## Ref: https://unix.stackexchange.com/questions/14961/how-to-find-out-which-interface-am-i-using-for-connecting-to-the-internet
## Ref: https://unix.stackexchange.com/questions/297139/sourcing-a-file-multiple-times-in-a-bash-script
## Ref: https://stackoverflow.com/questions/23513045/how-to-check-if-a-process-is-running-inside-docker-container
## Ref: https://stackoverflow.com/questions/20010199/how-to-determine-if-a-process-runs-inside-lxc-docker
## Ref: https://unix.stackexchange.com/questions/343942/shell-check-if-docker-container-is-existing
## Ref: https://stackoverflow.com/questions/20406134/read-a-bash-variable-assignment-from-other-file
## Ref: https://unix.stackexchange.com/questions/311758/remove-specific-word-in-variable
## Ref: https://stackoverflow.com/questions/13210880/replace-one-substring-for-another-string-in-shell-script
## Ref: https://stackoverflow.com/questions/11953185/counting-the-number-of-dots-in-a-string
## Ref: https://stackoverflow.com/questions/21157435/how-can-i-compare-a-string-to-multiple-correct-values-in-bash
## Ref: https://stackoverflow.com/questions/4792434/redis-on-web-server-front-end-or-database-server-back-end

## SS_EOF