Multithreaded Grep

A high-performance, multithreaded, recursive file search tool for text patterns, similar to Unix grep, written in Java.

Features

• Recursive search through directories
• Multithreaded for fast performance
• Case-insensitive matching by default
• Only .txt files are searched by default

Note: The tool currently counts and displays matches per line, not per occurrence. If a word appears multiple times in the same line, it will be reported as a single match for that line, not as multiple matches.

Example: If a line in the file is:

Hello world! This line says hello again: hello.

and you search for hello, this line will be counted as one match, even though hello appears three times in the line. And the output will look like:

./bin/multithreaded-grep test-data "HeLLo"
Total match(es): 1
test-data/sample0.txt:1:Hello world! This line says hello again: hello

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Out of Scope

• Regex support: The tool does not support regular expressions; only plain-text search is available.
• Escape sequence support: Patterns are matched as plain text; escape sequences like \t, \n, etc., are not interpreted.
• Counting actual occurrences: The tool does not count or display the number of times a pattern appears within a single line; it only reports per-line matches.

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Requirements

• Java 17 or higher
• Maven 3.x

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Setup

1. Clone the repository:

   git clone <your-repo-url>
   cd multithreaded-grep

2. Build the project with Maven:

   mvn clean package

   This will generate the executable JAR at target/multithreaded-grep-1.0-SNAPSHOT.jar.

3. (Optional) Make the bin tool executable:

   chmod +x bin/multithreaded-grep

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Usage

Command Line

Run the tool using the provided script:

./bin/multithreaded-grep <root_directory> <search_pattern>

Arguments

• <root_directory>: The directory to search recursively (e.g., test-data)
• <search_pattern>: The text pattern to search for (e.g., hello world)

Options

• -h, --help: Show usage instructions

Examples

Search for the phrase "hello world" in all .txt files under test-data/:

./bin/multithreaded-grep test-data "hello world"

Search for lines containing an email address:

./bin/multithreaded-grep test-data "[email protected]"

Sample Output

Total match(es): 2
test-data/sample0.txt:3:Hello world! This line contains the word "Hello".
test-data/sample1.txt:5:Double Quoted text: "hello world" in quotes

If no matches are found:

No matches found for pattern: <search_pattern>

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Development & Testing

• Run all tests:

  mvn test

• Test files are located in src/test/java/ and sample data in test-data/.

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Project Structure

multithreaded-grep/
├── bin/                  # Executable script for running the tool
├── src/
│   ├── main/java/        # Application source code
│   └── test/java/        # Unit and integration tests
├── test-data/            # Sample .txt files for testing/demo
├── pom.xml               # Maven build file
└── README.md             # Project documentation

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