Fortsh - Fortran Shell

A modern Unix shell implementation written in Fortran 2018 that demonstrates Fortran's capability for system programming.

Features

🔧 Advanced I/O Redirection

• Pipes and pipeline processing
• Here-strings (<<<) and here-documents (<<)
• Process substitution and combined redirections
• File redirection with append and truncate modes

📜 Full Scripting Support

• For-in loops, while loops, and control flow
• Functions with local variables
• Variable expansion and environment management
• Conditional execution (if/then/else/fi)

⚙️ Job Control

• Background job execution (&)
• Suspend/resume functionality
• Process group management
• Built-in commands: jobs, fg, bg, kill, wait

🔍 Pattern Matching & Globbing

• Wildcard patterns: *, ?, [abc], [a-z]
• Recursive pattern matching algorithm
• Sorted glob expansion results
• Directory-aware pattern matching

📊 Performance Monitoring

• Real-time execution timing
• Memory allocation tracking
• Built-in performance commands (perf, memory)
• Memory pool optimization
• Runtime statistics and profiling

🛡️ Error Handling

• Comprehensive test suite
• Robust error categorization
• Memory leak prevention
• Signal handling and cleanup

Quick Start

Installation

From Repository (Recommended)

# Add repository
sudo wget -O /etc/yum.repos.d/fortsh.repo https://repos.musicsian.com/fortsh.repo

# Install fortsh  
sudo dnf install fortsh

Build from Source

git clone https://github.com/FortranGoingOnForty/fortsh.git
cd fortsh
make all
make dev-install

Usage Examples

# Start the shell
fortsh

# Enable performance monitoring
export FORTSH_PERF=1
fortsh

# Basic scripting
for file in *.txt; do
    echo "Processing: $file"
done

# Job control
command &    # Background execution
jobs         # List active jobs
fg %1        # Bring job to foreground

# Pattern matching
echo *.{txt,log}    # Multiple extensions
echo test-[0-9]*    # Character ranges

Performance Features

# Runtime performance monitoring
perf on              # Enable monitoring
perf                 # Show statistics
memory               # Memory usage info

# Example output:
# ====================================
# FORTSH PERFORMANCE STATISTICS  
# ====================================
# Uptime:           .002 seconds
# Total commands:   9
# Avg parse time:   .009 ms
# Avg exec time:    .115 ms
# Current memory:   4608 bytes
# Peak memory:      14592 bytes

Architecture

Fortsh is built with a modular architecture:

• Common: Core types, error handling, performance monitoring
• System: OS interface layer, signal handling
• Parsing: Command parsing, glob expansion
• Execution: Command execution, job control, built-ins
• Scripting: Variables, control flow, configuration
• I/O: Readline interface and input handling

Requirements

• Operating System: Linux (RHEL 9, CentOS Stream 9, Rocky Linux 9, AlmaLinux 9, Fedora)
• Architecture: x86_64
• Build Dependencies: gfortran >= 11.0, make, gcc
• Runtime Dependencies: glibc

Development

Building

make all        # Build the shell
make test       # Run integration tests
make check      # Run comprehensive checks
make smoke-test # Basic functionality tests

Packaging

make dist       # Create distribution tarball
make rpm        # Build RPM packages

Installation

make install       # System-wide installation (/usr/local/bin)
make dev-install   # User installation (~/.local/bin)
make uninstall     # Remove installation

Performance

Fortsh includes comprehensive performance monitoring:

• Parsing: ~0.009ms average per command
• Execution: ~0.115ms average per command
• Memory: Automatic optimization with pools
• Profiling: Built-in timing and allocation tracking

Testing

Comprehensive test suite with:

• Integration tests for all major features
• Memory leak detection
• Performance regression testing
• Error condition handling

./tests/integration_test.sh    # Full test suite
make smoke-test                # Quick verification

License

MIT License - See LICENSE file for details.

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes with tests
4. Submit a pull request

Support

• Issues: https://github.com/FortranGoingOnForty/fortsh/issues
• Documentation: https://repos.musicsian.com/fortsh.html
• Repository: https://repos.musicsian.com/

Fortsh demonstrates that Fortran is not just for scientific computing - it's capable of modern system programming and can compete with traditional system languages for shell implementation.