Linux-Server-Management-Toolkit/docs/VARIABLES-QUICK-REFERENCE.md

System Variables - Quick Reference Card

Use this card when updating scripts to find the right variable to use

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Just Add This to Your Script

#!/bin/bash
set -eo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
BASE_DIR="$(cd "$SCRIPT_DIR/../.." && pwd)"
source "$BASE_DIR/lib/system-variables.sh"

# Now all SYS_* variables are available

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Lookup: What Variable Do I Need?

"I need to read/write to ___"

Web Server Logs

Task	Variable	Notes
Main access log	$SYS_LOG_WEB_ACCESS	Works on all platforms
Main error log	$SYS_LOG_WEB_ERROR	Works on all platforms
Domain-specific logs	$SYS_LOG_WEB_DOMAIN_ACCESS	cPanel, Plesk, InterWorx
Domain error logs	$SYS_LOG_WEB_DOMAIN_ERROR	cPanel, Plesk, InterWorx

Auth/System Logs

Task	Variable	Notes
SSH/sudo/login log	$SYS_LOG_AUTH	/var/log/auth.log or /var/log/secure
Failed logins (binary)	$SYS_LOG_BTMP	Binary file - use lastb
Successful logins (binary)	$SYS_LOG_WTMP	Binary file - use last

Mail Logs

Task	Variable	Notes
Mail server log	$SYS_LOG_MAIL_MAIN	Main mail log
Mail rejects (Exim)	$SYS_LOG_MAIL_REJECT	Only on Exim systems
Mail panic (Exim)	$SYS_LOG_MAIL_PANIC	Only on Exim systems
Mail queue directory	$SYS_MAIL_QUEUE_DIR	Varies by mail system

Firewall Logs

Task	Variable	Notes
Firewall log	$SYS_LOG_FIREWALL	CSF, firewalld, iptables, UFW
Firewall blocks	$SYS_LOG_FIREWALL_BLOCK	Block events (CSF only)

Database Logs

Task	Variable	Notes
MySQL error log	$SYS_LOG_DB_ERROR	Error and warnings
Slow query log	$SYS_LOG_DB_SLOW	Queries slower than threshold

Control Panel Logs

Task	Variable	Notes
cPanel WHM log	$SYS_LOG_PANEL	cPanel logs directory
cPanel access log	$SYS_LOG_PANEL_ACCESS	cPanel access log
cPanel error log	$SYS_LOG_PANEL_ERROR	cPanel error log

Security/System Logs

Task	Variable	Notes
System log	$SYS_LOG_SYSTEM	syslog or messages
Kernel log	$SYS_LOG_KERN	Kernel messages
Audit log	$SYS_LOG_AUDIT	SELinux/audit log
Package manager log	$SYS_LOG_PKG_MGR	apt or yum history

Scanner Logs

Task	Variable	Notes
ClamAV log	$SYS_LOG_CLAMAV	Antivirus
Maldet log	$SYS_LOG_MALDET	Linux Malware Detect
Rkhunter log	$SYS_LOG_RKHUNTER	Rootkit Hunter
Imunify log	$SYS_LOG_IMUNIFY	Imunify360

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"I need to connect to ___"

MySQL/MariaDB

Task	Variable	Notes
Database socket	$SYS_DB_SOCKET	Use with -S flag in mysql
Database config	$SYS_DB_CONFIG	MySQL config file
Database error log	$SYS_LOG_DB_ERROR	Check for connection errors

Example:

mysql -S "$SYS_DB_SOCKET" -u root -e "SHOW DATABASES"
tail -f "$SYS_LOG_DB_ERROR"

PostgreSQL

Task	Variable	Notes
PostgreSQL socket	$SYS_PG_SOCKET	Socket directory
PostgreSQL config	$SYS_PG_CONFIG	PostgreSQL config dir
PostgreSQL data	$SYS_PG_DATA_DIR	Data directory

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"I need to work with ___"

User Home Directories

Task	Variable	Notes
Base home path	$SYS_USER_HOME_BASE	/home or /var/www/vhosts or /chroot/home
cPanel users dir	$SYS_CPANEL_USERS_DIR	/var/cpanel/users (cPanel only)
cPanel user data	$SYS_CPANEL_USERDATA_DIR	/var/cpanel/userdata (cPanel only)
Plesk vhosts base	$SYS_PLESK_VHOSTS_BASE	/var/www/vhosts (Plesk only)
InterWorx chroot	$SYS_INTERWORX_CHROOT_BASE	/chroot/home (InterWorx only)

cPanel Specific

Task	Variable	Notes
cPanel version	$SYS_CPANEL_VERSION_FILE	Read to get version
cPanel scripts	$SYS_CPANEL_SCRIPTS_DIR	cPanel scripts directory
cPanel tools	$SYS_CPANEL_HULK_CTL	cPHulk control tool
cPanel main IP	$SYS_CPANEL_MAINIP_FILE	Read to get main IP
Domain logs	$SYS_CPANEL_DOMAIN_LOGS	Per-domain log directory

Plesk Specific

Task	Variable	Notes
Plesk version	$SYS_PLESK_VERSION_FILE	Read to get version
Plesk log version	$SYS_PLESK_LOG_STRUCTURE	"new" (18.0.50+) or "old"
Plesk logs base	$SYS_PLESK_VHOSTS_LOGS_BASE	/var/www/vhosts/system or /var/www/vhosts

InterWorx Specific

Task	Variable	Notes
InterWorx logs	$SYS_INTERWORX_LOGS_DIR	InterWorx log directory
iworx log	$SYS_INTERWORX_IWORX_LOG	Panel log
siteworx log	$SYS_INTERWORX_SITEWORX_LOG	Site log

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"I need to manage a service"

Service Names

Service	Variable	Values
Web server	$SYS_WEB_SERVICE	"httpd", "apache2", "nginx", "lsws"
Database	$SYS_DB_SERVICE	"mysqld", "mariadb", "postgresql"
Mail	$SYS_MAIL_SERVICE	"exim", "postfix", "sendmail"
SSH	$SYS_AUTH_SERVICE	"sshd"
Firewall	$SYS_FIREWALL_SERVICE	"csf", "firewalld", etc.

Use with:

restart_service "$SYS_WEB_SERVICE"
is_service_running "$SYS_DB_SERVICE"

Service Control Commands

Task	Variable	Usage
Restart	$SYS_SERVICE_RESTART	"$SYS_SERVICE_RESTART" "$SYS_WEB_SERVICE"
Start	$SYS_SERVICE_START	"$SYS_SERVICE_START" "$SYS_WEB_SERVICE"
Stop	$SYS_SERVICE_STOP	"$SYS_SERVICE_STOP" "$SYS_WEB_SERVICE"
Status	$SYS_SERVICE_STATUS	"$SYS_SERVICE_STATUS" "$SYS_WEB_SERVICE"
Enable	$SYS_SERVICE_ENABLE	"$SYS_SERVICE_ENABLE" "$SYS_WEB_SERVICE"

Or use convenience function:

restart_service "$SYS_WEB_SERVICE"  # Works on all systems

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"I need to check/install/configure ___"

Web Server Configuration

Task	Variable	Notes
Apache main config	$SYS_APACHE_MAIN_CONFIG	Apache only
Apache config dir	$SYS_APACHE_CONFIG_DIR	Apache only
Apache mods enabled	$SYS_APACHE_MODS_DIR	Apache only
Nginx main config	$SYS_NGINX_MAIN_CONFIG	Nginx only
Nginx config dir	$SYS_NGINX_CONFIG_DIR	Nginx only

Security/Firewall Configuration

Task	Variable	Notes
ModSecurity config	$SYS_MODSECURITY_CONF	If installed
CSF config	$SYS_CSF_CONFIG	CSF firewall
CSF allow list	$SYS_CSF_ALLOW	CSF whitelist
CSF deny list	$SYS_CSF_DENY	CSF blacklist

SSL/TLS Certificates

Task	Variable	Notes
Certificate dir	$SYS_SSL_CERT_DIR	/etc/ssl/certs
Private keys dir	$SYS_SSL_KEY_DIR	/etc/ssl/private
Let's Encrypt live	$SYS_LETSENCRYPT_LIVE	Live certificates
cPanel SSL dir	$SYS_CPANEL_SSL_DIR	cPanel only

Package Manager

Task	Variable	Notes
Install cmd	$SYS_PKG_MANAGER_INSTALL	With flags
Remove cmd	$SYS_PKG_MANAGER_REMOVE	With flags
Update cmd	$SYS_PKG_MANAGER_UPDATE	With flags
Cache dir	$SYS_PACKAGE_CACHE	/var/cache/apt or /var/cache/yum

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Detection Variables (For Conditionals)

# What platform detected?
if [ "$SYS_CONTROL_PANEL" = "cpanel" ]; then
    # cPanel-specific code
fi

# What OS?
if [ "$SYS_OS_TYPE" = "ubuntu" ]; then
    # Debian-specific code
fi

# What web server?
if [ "$SYS_WEB_SERVER" = "nginx" ]; then
    # Nginx-specific code
fi

# What database?
if [ "$SYS_DB_TYPE" = "postgresql" ]; then
    # PostgreSQL-specific code
fi

# What init system?
if [ "$SYS_INIT_SYSTEM" = "systemd" ]; then
    # systemd-specific code
fi

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Common Patterns

Check if service is installed

if [ -n "$SYS_WEB_SERVICE" ]; then
    echo "Web server installed: $SYS_WEB_SERVICE"
fi

Check if log file exists and is readable

if [ -f "$SYS_LOG_WEB_ERROR" ]; then
    tail -f "$SYS_LOG_WEB_ERROR"
fi

Work with domain-specific logs (varies by platform)

if [ -n "$SYS_LOG_WEB_DOMAIN_ACCESS" ]; then
    find "$SYS_LOG_WEB_DOMAIN_ACCESS" -name "*.log"
fi

Database operations

# Read-only check
mysql -S "$SYS_DB_SOCKET" -u root -e "SELECT COUNT(*) FROM information_schema.SCHEMATA"

# Monitor errors
tail -f "$SYS_LOG_DB_ERROR"

Service management

# Restart web server (works on systemd and sysvinit)
restart_service "$SYS_WEB_SERVICE"

# Or manual
"$SYS_SERVICE_RESTART" "$SYS_WEB_SERVICE"

cPanel operations

# List all users (cPanel)
if [ "$SYS_CONTROL_PANEL" = "cpanel" ]; then
    ls "$SYS_CPANEL_USERS_DIR"
fi

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Error Handling Template

#!/bin/bash
set -eo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
BASE_DIR="$(cd "$SCRIPT_DIR/../.." && pwd)"
source "$BASE_DIR/lib/system-variables.sh"

# Check if required log exists
if [ -z "$SYS_LOG_WEB_ACCESS" ] || [ ! -f "$SYS_LOG_WEB_ACCESS" ]; then
    echo "ERROR: Web access log not found at $SYS_LOG_WEB_ACCESS"
    exit 1
fi

# Check if required variable is set
if [ -z "$SYS_DB_SOCKET" ]; then
    echo "ERROR: Database not detected on this system"
    exit 1
fi

# Your script code here

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When Variables Are Empty

Some variables may be empty on certain systems:

Variable	Empty When
SYS_CPANEL_*	Not on cPanel
SYS_PLESK_*	Not on Plesk
SYS_INTERWORX_*	Not on InterWorx
SYS_LOG_MAIL_REJECT	Not Exim mail system
SYS_LOG_DB_SLOW	Database not detected
SYS_NGINX_*	Not using Nginx
SYS_APACHE_*	Not using Apache

Always check before using:

if [ -n "$SYS_CPANEL_USERS_DIR" ]; then
    # cPanel specific code
fi

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Full Reference

For complete documentation with examples, see:

• docs/SYSTEM-VARIABLES-REFERENCE.md - All 140+ variables documented
• docs/SYSTEM-VARIABLES-MAPPING-COMPLETE.md - Coverage and examples
• docs/SYSTEM-VARIABLES-READY-FOR-UPDATES.md - Migration guide