📁 OpenTTY File System

The OpenTTY file system is a virtual file system that provides a unified interface to access different types of storage resources within the J2ME environment. It combines RMS storage, device file systems, virtual directories, and temporary storage into a single hierarchical structure.

🗂️ File System Structure

📍 Root Directories

/
├── /home/          # 📝 RMS Record Stores (User Files)
├── /tmp/           # 🗑️ Temporary In-Memory Storage
├── /mnt/           # 💾 Device File System (JSR-75)
├── /bin/           # ⚡ Executable Scripts & Applications
├── /lib/           # 📚 Library Packages
├── /dev/           # 🔧 Special Devices
└── /res/           # 📦 Resource Files (JAR Resources)

🔧 Directory Details

🏠 `/home/` - User Storage

Storage: RMS Record Stores
Permissions: Read/Write for current user
Features:
- Persistent storage across sessions
- File management via RecordStore API
- User-specific data storage

🗑️ `/tmp/` - Temporary Storage

Storage: In-memory Hashtable
Permissions: Read/Write
Features:
- Volatile storage (lost on exit)
- Fast access for temporary files
- Session-specific data

💾 `/mnt/` - Device File System

Storage: JSR-75 FileConnection API
Permissions: Device-dependent
Features:
- Access to device file system
- Directory listing and file operations
- Cross-platform file access

⚡ `/bin/` - Executables

Storage: Packaged scripts in RMS
Permissions: Read-only (root can modify)
Features:
- Shell commands and scripts
- Auto-execution via classpath
- System utilities

📚 `/lib/` - Libraries

Storage: Packaged libraries in RMS
Permissions: Read-only (root can modify)
Features:
- Shared packages and modules
- Function libraries
- Extension packages

🔧 `/dev/` - Special Devices

Virtual Devices:
- stdin - Command input field
- stdout - Output display
- null - Empty device
- random - Random number generator
- zero - Zero byte source
- tty - Terminal source

🛠️ File Operations

📋 Listing Files

ls /home/          # List user files
ls /mnt/           # List device roots
dir                # GUI file browser

📄 Reading Files

cat /home/notes.txt     # Read RMS file
cat /mnt/root/file.txt  # Read device file
cat /tmp/buffer         # Read temporary file

✏️ Writing Files

install /home/script.sh         # Install from nano buffer
touch /tmp/tempfile             # Create temporary file

🗑️ Deleting Files

rm /home/oldfile.txt    # Delete RMS record
rm /mnt/file.txt       # Delete device file
rm /tmp/tempfile       # Remove temporary file

🔐 Permissions Model

👤 User Types

Root (id=0): Full system access
Regular User (id=1000): Limited access

🔒 Permission Rules

/home/: User can read/write their own files
/tmp/: User can read/write all files
/mnt/: Device-dependent permissions
/bin/, /lib/: Read-only for users, writable by root
System files: Read-only for all users

🎮 Special Features

📁 Virtual Directories

Mount System: Create virtual directories via configuration
Path Resolution: Automatic path completion
Directory Stack: pushd/popd for navigation

🔄 File Types & Detection

Automatic MIME type detection
File extension mapping
Binary vs Text classification

💽 Storage Management

RMS Compression: Multiple files in single RecordStore
Memory Management: Automatic garbage collection
Storage Quotas: Configurable limits

🚀 Usage Examples

pwd                    # Show current directory
cd /home/              # Change to home directory
ls -a                  # List all files (including hidden)

📊 File Information

file /home/document.txt    # Get file type information
wc /home/script.sh         # Count lines, words, characters
du /mnt/file.txt          # Get file size

🔄 Advanced Operations

cp /home/source.txt /tmp/copy.txt    # Copy files
mount /home/filesystem.conf          # Mount virtual directories
rmsfix swap /bin/ /home/backup/      # Backup system files

⚠️ Limitations

J2ME Constraints: Limited by device capabilities
Storage Size: RMS storage limitations apply
File Size: Memory constraints for large files
Permissions: Device security restrictions

The OpenTTY file system provides a Unix-like experience within J2ME constraints, enabling powerful file management capabilities on mobile devices!

🎯 Overview