mwc

A Go implementation of the Unix wc (word count) command line tool.

Description

mwc is a custom implementation of the Unix wc command, written in Go. It provides functionality to count bytes, lines, words, and characters in text files or from standard input.

Features

• Count bytes (-c)
• Count lines (-l)
• Count words (-w)
• Count characters (-m)
• Read from files or standard input
• Process multiple files
• Handles both ASCII and Unicode text
• Default behavior (equivalent to -c, -l, and -w options)
• Help option for usage information

Installation

To install mwc, make sure you have Go installed on your system, then run:

go get github.com/mvk059/mwc

Usage

mwc [-lwcm] [file ...]

Options:

• -l: Count lines
• -w: Count words
• -c: Count bytes
• -m: Count characters
• -h, --help: Display help message

If no options are specified, mwc defaults to counting lines, words, and bytes (equivalent to -lwc).

If no filename is provided, mwc reads from standard input.

Examples:

1. Count lines, words, and bytes in a file:

   mwc file.txt
   

2. Count only characters in multiple files:

   mwc -m file1.txt file2.txt
   

3. Count lines from standard input:

   cat file.txt | mwc -l
   

4. Count words and characters in multiple files:

   mwc -wm file1.txt file2.txt file3.txt
   

5. Use with echo command:

   echo 'Hello World!' | mwc
   

6. Display help message:

   mwc -h
   

   or

   mwc --help
   

Output

The output format is:

  <count1> <count2> ... <filename>

Where <count1>, <count2>, etc., are the counts for each specified option, in the order they were provided. The counts are right-aligned in 8-character wide fields.

If multiple files are provided, a total count is displayed at the end.

Implementation Details

This implementation addresses common mistakes often made in similar projects. For a detailed discussion of these mistakes, see From The Challenges: wc.

1. Efficient File Reading: The program reads files incrementally, avoiding loading entire files into memory. This allows it to handle files of arbitrary size without running out of memory.

2. Locale and Unicode Support: The character counting option (-m) correctly handles multi-byte Unicode characters, ensuring accurate counts across different locales.

3. Standard Input Support: The program can read from both files and standard input, allowing it to be used in command pipelines.

4. Comprehensive Testing: The project includes a robust test suite (mwc_test.go) that covers various scenarios, including edge cases and different input types.

Project Structure

• mwc.go: Main implementation of the word count functionality.
• mwc_test.go: Comprehensive test suite for the project.
• go.yml: GitHub Actions workflow for continuous integration.

Error Handling

• If an invalid option is provided, an error message is displayed, and the program exits.
• If a file cannot be opened or read, an error message is displayed, but the program continues processing other files if any.

Limitations

• Unicode handling might not be perfect for all edge cases.

Contributing

Contributions to mwc are welcome! Please feel free to submit a Pull Request.

License

This project is open source and available under the MIT License.

Acknowledgments

This project was created as an exercise in Go programming and to understand the inner workings of the wc command.

This project was also inspired by and developed as part of the Coding Challenges series. This is my solution to the "Build Your Own wc Tool" challenge.