fmt:tldr:bcc2d

The command fmt -w ${n} ${filename} is used to format and wrap text in a file named ${filename} to a specified width ${n}.

Here is what each part of the command does:

• fmt is the command itself, which is used to format text files.
• -w is an option or flag for fmt, which specifies the maximum width the text should be wrapped to.
• ${n} is a placeholder variable that should be replaced with a specific number. It represents the maximum width at which the text should be wrapped.
• ${filename} is also a placeholder variable that should be replaced with the actual name of the file on which the command needs to be applied.

So, when you run the command with the appropriate values, it will format the text in the specified file ${filename} and wrap it to the maximum width ${n}.