v.1.0.1: New version install_appimage.sh

v1.0.1 (2025-03-06)

Added

• Optional Checksum Verification: Introduced -c (inline checksum) and -C (checksum file) flags to allow users to verify the integrity of AppImages using sha256sum.
• Fallback .desktop Creation: Added logic to create a minimal .desktop file if the AppImage does not provide one (can be disabled via --no-fallback-desktop).
• Reinstall & Update Flags: Implemented -r (reinstall) and -u (update) options to handle existing installations.
• Dry-Run Mode: Enhanced the -n flag to simulate all file operations without actually modifying the system.
• Verbose Debug Mode: Added -v flag for more granular logging and troubleshooting.
• Distinct Exit Codes: Defined specific exit codes for common failure points (e.g., missing dependencies, extraction failure, checksum mismatch).

Changed

• Removed eval: Replaced all eval "$*" commands with a safer function that calls commands directly, preventing possible command injection vulnerabilities.
• Improved Error Handling: Script now provides clearer, more descriptive messages and exits early with the relevant exit code when critical steps fail (e.g., .desktop file not found, extraction failure).
• Better Maintainability: Refactored functions to be smaller and more focused, making the script easier to read and modify.

Fixed

• Permissions Handling: Ensured that the AppImage is set as executable (chmod +x) before extraction and after copying to the install location.
• Dependency Checks: Added checks for mktemp, find, grep, file, and sha256sum to ensure the user’s system is properly configured.