Installation

OS Detection Library for Install Scripts

The Talawa Admin repository includes a robust OS detection library (scripts/install/lib/os-detect.sh) that provides reliable cross-platform OS identification for bash installation scripts. This library is used internally by the automated installer and can be leveraged by developers creating custom installation or setup scripts.

Overview

The OS detection library provides:

• Cross-platform OS detection for macOS, Debian/Ubuntu, RHEL/Fedora, and WSL variants
• Cached results for performance (subsequent calls are instant)
• Safe handling of missing system files
• Alignment with the TypeScript OS detector (src/install/os/detector.ts)

Usage

To use the OS detection library in your bash scripts:

# Source the library
source ./scripts/install/lib/os-detect.sh

# Detect the operating system
detect_os

# Access the results
echo "$OS_TYPE"           # e.g., "macos", "debian", "wsl-debian"
echo "$OS_DISPLAY_NAME"   # e.g., "macOS", "WSL (Debian/Ubuntu)"
echo "$IS_WSL"            # "true" or "false"

Exported Variables

After calling detect_os, the following variables are available:

Variable	Type	Description	Example Values
OS_TYPE	String	OS type identifier	macos, debian, redhat, wsl-debian, wsl-redhat, wsl-unknown, unknown
OS_DISPLAY_NAME	String	Human-readable OS name	macOS, Debian/Ubuntu, WSL (Debian/Ubuntu)
IS_WSL	Boolean	Whether running in WSL	true, false

Exported Functions

Function	Description	Returns
detect_os	Detects OS and sets exported variables. Idempotent (cached after first call).	Always returns 0
get_os_display_name	Calls detect_os and returns the human-readable OS name	OS display name via stdout

Supported Operating Systems

The library detects the following operating system types:

• macOS (OS_TYPE="macos") - Native macOS systems
• Debian/Ubuntu (OS_TYPE="debian") - Native Debian-based Linux systems
• RHEL/Fedora (OS_TYPE="redhat") - Native RHEL-based Linux systems
• WSL Debian (OS_TYPE="wsl-debian") - Windows Subsystem for Linux running Debian/Ubuntu
• WSL RHEL (OS_TYPE="wsl-redhat") - Windows Subsystem for Linux running RHEL/Fedora
• WSL Unknown (OS_TYPE="wsl-unknown") - Windows Subsystem for Linux with unrecognized distro
• Unknown (OS_TYPE="unknown") - Fallback for unsupported systems

Example Script

#!/bin/bash
set -euo pipefail

# Source the OS detection library
source "$(dirname "$0")/scripts/install/lib/os-detect.sh"

# Detect the operating system
detect_os

# Use OS information to customize installation
case "$OS_TYPE" in
    macos)
        echo "Installing for macOS..."
        brew install package-name
        ;;
    debian)
        echo "Installing for Debian/Ubuntu..."
        sudo apt-get install -y package-name
        ;;
    redhat)
        echo "Installing for RHEL/Fedora..."
        sudo dnf install -y package-name
        ;;
    wsl-*)
        echo "Detected WSL environment: $OS_DISPLAY_NAME"
        # Special handling for WSL
        ;;
    *)
        echo "Unsupported OS: $OS_DISPLAY_NAME"
        exit 1
        ;;
esac

Important Notes

• Multiple Sourcing: The library is safe to source multiple times - it will only execute once per shell session
• Caching: The detect_os function caches results after the first call for performance
• Bash Compatibility: Compatible with Bash 3.2+ (macOS default) and later versions
• No System Modifications: The library only reads system files and never modifies them

Testing

The library includes a comprehensive test suite at scripts/install/lib/os-detect.spec.sh:

# Run all tests
bash scripts/install/lib/os-detect.spec.sh

# Or make it executable and run
chmod +x scripts/install/lib/os-detect.spec.sh
./scripts/install/lib/os-detect.spec.sh

The test suite covers:

• Detection for all supported OS types
• WSL detection (via environment variable and /proc/version)
• Caching and idempotency behavior
• Variable exports and function behavior
• Edge cases and unknown OS handling