Master Linux fmt: Format Text, Adjust Width, and Highlight Lines

The fmt command is a simple yet powerful Linux utility for reformatting plain‑text files, making paragraphs tidy and improving readability. By default it wraps lines to 75 characters, but you can customize the width and other formatting options.

Basic Usage

The general syntax is: fmt [-WIDTH] [OPTION]... [FILE]... It reads each paragraph, reformats it, and writes the result to standard output. The -WIDTH option lets you set a specific line width.

Q1: How to format a file into a single line?

Running fmt without options collapses the entire file into one continuous line: fmt filename The original file remains unchanged.

Q2: How to change the maximum line width?

Use the -w option followed by a number to set a custom width, e.g., 20 characters:

fmt -w 20 filename

Q3: How to highlight the first line?

Apply the -t option to give the first line a different indentation, making it stand out:

fmt -t filename

Q4: How to split overly long lines?

The -s option forces fmt to break lines that exceed the specified width, improving paragraph structure:

fmt -s filename

Q5: How to set word and sentence spacing?

With the -u option, fmt inserts a single space between words and two spaces between sentences, which is enabled by default:

fmt -u filename

Summary

Although fmt offers a modest feature set, it remains an effective tool for quick text reformatting, line‑width adjustment, and consistent typography. For more advanced options, consult the manual page.