Unix Utilities

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Overview

This project involves building simple versions of common UNIX command-line utilities in C++, Trying to deepen understanding of UNIX systems programming.

The utilities implemented include:

• wcat: Simplified implementation of the UNIX cat command.
• wgrep: A minimalistic version of the UNIX grep command.
• wzip & wunzip: Basic compression and decompression utilities for file management.

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Objectives

Through this project, I aim to:

• Strengthen proficiency in C/C++ programming.
• Enhance familiarity with UNIX shell and command-line environments.
• Master fundamental file I/O operations using system calls (open, read, write, close).
• Understand basic text processing and file manipulation techniques.
• Develop experience in writing robust, error-handling code compliant with UNIX standards.

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Project Structure

project_root/
├── wcat.cpp    # Reads and prints file contents (simplified cat)
├── wgrep.cpp   # Searches text files for matching patterns
├── wzip.cpp    # Simple run-length file compression
└── wunzip.cpp  # Decompression utility for files compressed with wzip

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Compiling the Utilities

To compile each utility, use the provided flags for warnings and errors:

g++ -g -Wall -Werror -o wcat wcat.cpp

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Utility Details

1. wcat

• Purpose: Reads specified files and prints their contents.
• Usage:

  ./wcat file1.cpp file2.cpp

• Error Handling: Outputs "wcat: cannot open file" if file open operation fails.

Core Learning Points:

• Using file descriptors and system calls (open, read, write, close).
• Handling command-line arguments in C++.

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wgrep Utility

• Description: Searches for lines containing a specific string across multiple files.
• Usage:

  ./wgrep "search_term" file.txt

• Error Handling: Outputs "wgrep: cannot open file" on failure to open files.

Core Learning Points:

• Buffer management for processing arbitrary-length lines.
• Using standard input/output for flexible I/O operations.

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File Compression: wzip & wunzip

• wzip compresses files using run-length encoding, writing output in binary format.
• wunzip decompresses files compressed with wzip.

Example usage:

./wzip file.txt > compressed.z
./wunzip compressed.z

Core Learning Points:

• Binary I/O operations and handling non-ASCII data.
• Implementing compression algorithms (run-length encoding).

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Technical Requirements

Each utility must:

• Compile without warnings/errors (-Wall, -Werror).
• Pass provided test cases and handle additional custom tests.

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Technical Skills & Tools

• Languages: C/C++
• System Calls: open, read, write, close
• Tools: GCC/G++ compiler, Unix command-line interface
• Editor: Familiarity with editors such as Emacs or Vim

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Future Improvements

• Extend utilities with additional features (e.g., command-line flags).
• Implement advanced compression algorithms.
• Enhance error handling robustness.

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License

Licensed under the MIT License - see LICENSE file for details.

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