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🐚 🌍 TuskLang Bash @env Function Guide

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🌍 TuskLang Bash @env Function Guide

"We don't bow to any king" – Environment variables are your configuration's lifeblood.

The @env function in TuskLang is your gateway to dynamic, environment-aware configuration. Whether you're managing different deployment environments, handling sensitive data, or building portable applications, @env provides the flexibility to adapt your configuration to any environment without code changes.

🎯 What is @env?

The @env function accesses environment variables with optional fallback values. It provides: - Environment awareness - Different values for different environments - Security - Access to sensitive configuration data - Portability - Configuration that works across systems - Flexibility - Optional fallbacks for missing variables - Type safety - Automatic type conversion for common types

📝 Basic @env Syntax

Simple Environment Access

[basic]

Access environment variables

api_key: @env("API_KEY")
database_url: @env("DATABASE_URL")
debug_mode: @env("DEBUG")

With Fallback Values

[with_fallbacks]

Provide default values when environment variables are not set

host: @env("HOST", "localhost")
port: @env("PORT", "8080")
timeout: @env("TIMEOUT", "30")

Type-Specific Access

[typed]

Convert to specific types

port: @int(@env("PORT", "8080"))
timeout: @float(@env("TIMEOUT", "30.0"))
debug: @bool(@env("DEBUG", "false"))
workers: @int(@env("WORKERS", "4"))

🚀 Quick Start Example

#!/bin/bash
source tusk-bash.sh
Set some environment variables for testing

export APP_ENV="development"
export API_KEY="test_api_key_12345"
export DB_HOST="localhost"
export DEBUG="true"
cat > env-quickstart.tsk << 'EOF'
[application]
name: "TuskApp"
version: "2.1.0"
environment: @env("APP_ENV", "production")
debug_mode: @bool(@env("DEBUG", "false"))
[api]
key: @env("API_KEY")
base_url: @env("API_BASE_URL", "https://api.example.com")
timeout: @int(@env("API_TIMEOUT", "30"))
[database]
host: @env("DB_HOST", "localhost")
port: @int(@env("DB_PORT", "5432"))
name: @env("DB_NAME", "tuskapp")
user: @env("DB_USER", "postgres")
password: @env("DB_PASSWORD", "")
[server]
host: @env("SERVER_HOST", "0.0.0.0")
port: @int(@env("SERVER_PORT", "8080"))
workers: @int(@env("WORKERS", "4"))
EOF
config=$(tusk_parse env-quickstart.tsk)
echo "Application: $(tusk_get "$config" application.name) v$(tusk_get "$config" application.version)"
echo "Environment: $(tusk_get "$config" application.environment)"
echo "Debug Mode: $(tusk_get "$config" application.debug_mode)"
echo "API Key: $(tusk_get "$config" api.key)"
echo "Database: $(tusk_get "$config" database.host):$(tusk_get "$config" database.port)"
echo "Server: $(tusk_get "$config" server.host):$(tusk_get "$config" server.port)"

🔗 Real-World Use Cases

1. Environment-Specific Configuration

[environment_config]

Different settings for different environments

environment: @env("APP_ENV", "development")
Environment-specific database settings

database_host: @if($environment == "production", 
    @env("PROD_DB_HOST", "prod-db.example.com"),
    @env("DEV_DB_HOST", "localhost")
)
database_port: @if($environment == "production", 
    @int(@env("PROD_DB_PORT", "5432")),
    @int(@env("DEV_DB_PORT", "5432"))
)
Environment-specific logging

log_level: @if($environment == "production", "error", "debug")
log_file: @if($environment == "production", "/var/log/app.log", "/tmp/app.log")

2. Secure Configuration Management

[secure_config]

Use secure environment variables for sensitive data

encryption_key: @env.secure("ENCRYPTION_KEY")
api_secret: @env.secure("API_SECRET")
database_password: @env.secure("DB_PASSWORD")
session_secret: @env.secure("SESSION_SECRET")
Regular environment variables for non-sensitive data

app_name: @env("APP_NAME", "TuskApp")
app_version: @env("APP_VERSION", "2.1.0")
debug_mode: @bool(@env("DEBUG", "false"))

3. Docker and Container Configuration

[container_config]

Container-aware configuration

container_id: @env("HOSTNAME", "unknown")
pod_name: @env("POD_NAME", "unknown")
namespace: @env("NAMESPACE", "default")
Resource limits from environment

memory_limit: @env("MEMORY_LIMIT", "512Mi")
cpu_limit: @env("CPU_LIMIT", "500m")
max_workers: @int(@env("MAX_WORKERS", "4"))
Service discovery

database_host: @env("DB_HOST", "localhost")
redis_host: @env("REDIS_HOST", "localhost")
api_gateway: @env("API_GATEWAY", "http://localhost:8080")

4. Feature Flags and A/B Testing

[feature_flags]

Feature flags from environment variables

feature_new_ui: @bool(@env("FEATURE_NEW_UI", "false"))
feature_analytics: @bool(@env("FEATURE_ANALYTICS", "true"))
feature_beta: @bool(@env("FEATURE_BETA", "false"))
A/B testing configuration

ab_test_group: @env("AB_TEST_GROUP", "control")
ab_test_percentage: @int(@env("AB_TEST_PERCENTAGE", "50"))
Dynamic feature configuration

max_upload_size: @int(@env("MAX_UPLOAD_SIZE", "100"))
cache_ttl: @int(@env("CACHE_TTL", "300"))
rate_limit: @int(@env("RATE_LIMIT", "1000"))

🧠 Advanced @env Patterns

Conditional Configuration

#!/bin/bash
source tusk-bash.sh
cat > conditional-env.tsk << 'EOF'
[conditional]
environment: @env("APP_ENV", "development")
Conditional database configuration

database_config: @if($environment == "production", {
    "host": @env("PROD_DB_HOST", "prod-db.example.com"),
    "port": @int(@env("PROD_DB_PORT", "5432")),
    "ssl": true
}, {
    "host": @env("DEV_DB_HOST", "localhost"),
    "port": @int(@env("DEV_DB_PORT", "5432")),
    "ssl": false
})
Conditional API configuration

api_config: @if($environment == "production", {
    "base_url": @env("PROD_API_URL", "https://api.example.com"),
    "timeout": @int(@env("PROD_API_TIMEOUT", "30")),
    "retries": @int(@env("PROD_API_RETRIES", "3"))
}, {
    "base_url": @env("DEV_API_URL", "http://localhost:3000"),
    "timeout": @int(@env("DEV_API_TIMEOUT", "10")),
    "retries": @int(@env("DEV_API_RETRIES", "1"))
})
EOF
config=$(tusk_parse conditional-env.tsk)
echo "Environment: $(tusk_get "$config" conditional.environment)"
echo "Database Host: $(tusk_get "$config" conditional.database_config.host)"
echo "API Base URL: $(tusk_get "$config" conditional.api_config.base_url)"

Environment Variable Validation

#!/bin/bash
source tusk-bash.sh
cat > env-validation.tsk << 'EOF'
[validation]

Required environment variables

api_key: @env("API_KEY")
database_url: @env("DATABASE_URL")
encryption_key: @env.secure("ENCRYPTION_KEY")
Validate required variables

@validate.required(["api_key", "database_url", "encryption_key"])
Optional variables with validation

port: @int(@env("PORT", "8080"))
@validate.range("port", 1, 65535)
timeout: @float(@env("TIMEOUT", "30.0"))
@validate.range("timeout", 1.0, 300.0)
email: @env("ADMIN_EMAIL", "admin@example.com")
@validate.email("email")
EOF
config=$(tusk_parse env-validation.tsk)
echo "API Key: $(tusk_get "$config" validation.api_key)"
echo "Port: $(tusk_get "$config" validation.port)"
echo "Timeout: $(tusk_get "$config" validation.timeout)"

Dynamic Configuration Loading

#!/bin/bash
source tusk-bash.sh
Function to load environment-specific configuration

load_env_config() {
    local env=${1:-development}
    local config_file="config/${env}.tsk"
    
    if [[ -f "$config_file" ]]; then
        echo "Loading configuration for environment: $env"
        tusk_parse "$config_file"
    else
        echo "Configuration file $config_file not found, using defaults" >&2
        # Return default configuration
        cat > /tmp/default.tsk << 'EOF'
[app]
name: "TuskApp"
environment: "default"
debug: false
EOF
        tusk_parse /tmp/default.tsk
    fi
}
Usage

config=$(load_env_config "$APP_ENV")
echo "Loaded configuration for: $(tusk_get "$config" app.environment)"

🛡️ Security & Performance Notes

- Secure environment variables: Use @env.secure for sensitive data like passwords and API keys - Validation: Always validate environment variables before using them - Fallbacks: Provide sensible default values for all environment variables - Type safety: Use type conversion functions (@int, @bool, @float) for proper type handling - Performance: Environment variable access is fast and cached

🐞 Troubleshooting

- Missing variables: Always provide fallback values to prevent configuration errors - Type mismatches: Use type conversion functions to ensure proper data types - Permission issues: Ensure proper permissions for accessing environment variables - Scope issues: Environment variables are process-scoped; child processes inherit them

💡 Best Practices

- Use descriptive names: Choose clear, descriptive environment variable names - Provide fallbacks: Always provide default values for optional environment variables - Validate inputs: Use @validate functions to ensure environment variables meet requirements - Document variables: Document all required and optional environment variables - Use secure variants: Use @env.secure for sensitive data - Type conversion: Use appropriate type conversion functions for data types

🔗 Cross-References

- @ Operator Introduction - @shell Operator - Validation - Security

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Master @env in TuskLang and build environment-aware, secure configurations. 🌍

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