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CLI Tools Implementation

Implement simplified versions of the classic Unix command-line tools: ls, grep, and wc. These projects will help you master basic C++ concepts and file system operations.

Project Structure​

The CLI tools are organized as follows:

phase1/cli-tools/
├── CMakeLists.txt
├── include/
│   ├── ls.h      # Header for ls functionality
│   ├── grep.h    # Header for grep functionality
│   └── wc.h      # Header for wc functionality
└── src/
    ├── ls_lib.cpp       # Implementation for ls functionality
    ├── ls_main.cpp      # Main entry point for ls command
    ├── grep_lib.cpp     # Implementation for grep functionality
    ├── grep_main.cpp    # Main entry point for grep command
    ├── wc_lib.cpp       # Implementation for wc functionality
    └── wc_main.cpp      # Main entry point for wc command

ls Command Implementation​

The my_ls command implements basic directory listing functionality.

Features to Implement​

  • List files in current directory by default
  • Accept directory path as argument
  • Show detailed file information (size, permissions, timestamps)
  • Support common flags like -l for long format

Sample Implementation Approach​

// Example: Basic ls functionality
#include <filesystem>
#include <iostream>

void list_directory(const std::string& path) {
    for (const auto& entry : std::filesystem::directory_iterator(path)) {
        std::cout << entry.path().filename() << std::endl;
    }
}

grep Command Implementation​

The my_grep command implements pattern matching in files.

Features to Implement​

  • Search for patterns in specified files
  • Support for regular expressions
  • Recursive directory search option
  • Line number and file name reporting

Sample Implementation Approach​

// Example: Basic grep functionality
#include <fstream>
#include <regex>
#include <string>

bool search_pattern(const std::string& filename, const std::string& pattern) {
    std::ifstream file(filename);
    std::string line;
    std::regex reg(pattern);
    
    int line_num = 1;
    while (std::getline(file, line)) {
        if (std::regex_search(line, reg)) {
            std::cout << filename << ":" << line_num << ":" << line << std::endl;
        }
        ++line_num;
    }
    return true;
}

wc Command Implementation​

The my_wc command implements word count functionality.

Features to Implement​

  • Count words, lines, and characters in files
  • Support multiple file inputs
  • Display total counts when multiple files are provided
  • Support options like -w, -l, -c for specific counts

Sample Implementation Approach​

// Example: Basic wc functionality
#include <fstream>
#include <string>

struct Counts {
    int lines = 0;
    int words = 0;
    int chars = 0;
};

Counts count_file(const std::string& filename) {
    std::ifstream file(filename);
    Counts counts;
    std::string line;
    
    while (std::getline(file, line)) {
        counts.lines++;
        counts.chars += line.length() + 1;  // +1 for newline
        
        // Count words by splitting on whitespace
        // Implementation depends on your approach
    }
    
    return counts;
}

Building and Running​

To build and run the CLI tools:

# In the Docker container
cd /app

# Build the project
mkdir -p build && cd build
cmake ..
make -j4

# Run specific commands
./phase1/cli-tools/my_ls [directory_path]
./phase1/cli-tools/my_grep [pattern] [file_path]
./phase1/cli-tools/my_wc [file_path]

Development Tips​

  • Use C++20 features like ranges when appropriate
  • Implement proper error handling for file operations
  • Pay attention to performance, especially for large files
  • Follow the project's code standards and documentation guidelines

Next Steps​

After implementing the CLI tools, move on to the JSON Parser project to tackle structured data parsing.