Python Grep Implementation

A Python implementation of the Unix grep command line tool, following the Coding Challenges specification.

Features

• Basic pattern matching with regular expressions
• Support for special patterns:
  • \d - matches any digit
  • \w - matches any word character
  • ^ - matches start of line
  • $ - matches end of line
• Command line options:
  • -i, --ignore-case: Case insensitive search
  • -n, --line-number: Show line numbers
  • -c, --count: Show only count of matching lines
  • -r, --recursive: Recursively search directories
  • -v, --invert-match: Show non-matching lines

Installation

No installation required. Just make sure you have Python 3.x installed on your system.

Usage

python grep.py [OPTIONS] PATTERN [FILE...]

Examples

1. Search for a simple pattern:

python grep.py "pattern" file.txt

2. Case-insensitive search:

python grep.py -i "Pattern" file.txt

3. Show line numbers:

python grep.py -n "pattern" file.txt

4. Count matching lines:

python grep.py -c "pattern" file.txt

5. Recursive search:

python grep.py -r "pattern" directory/

6. Invert match (show non-matching lines):

python grep.py -v "pattern" file.txt

7. Using special patterns:

python grep.py "\d" file.txt     # Match lines containing digits
python grep.py "\w" file.txt     # Match lines containing word characters
python grep.py "^Start" file.txt # Match lines starting with "Start"
python grep.py "End$" file.txt   # Match lines ending with "End"

Exit Codes

• 0: Match found
• 1: No match found
• 2: File not found or other error

Implementation Details

• Written in Python 3
• Uses built-in re module for regular expressions
• Handles binary files gracefully
• Supports UTF-8 encoded text files
• Windows PowerShell compatible

Limitations

• Only supports UTF-8 encoded text files
• Regular expression syntax is limited to basic patterns
• No support for multiple patterns

Contributing

Feel free to submit issues and enhancement requests!