expand:tldr:3d74e

The command "expand -t=${number} ${filename}" is used to modify the whitespace indentation of a file.

Here is a breakdown of each component of the command:

• "expand" is the command itself, which is used to expand tabs to spaces.
• "-t=${number}" specifies the width of the tabs in spaces. "${number}" is a placeholder for the desired number of spaces for each tab. For example, if you want each tab to be equivalent to 4 spaces, you would replace "${number}" with "4".
• "${filename}" is the name of the file you want to modify. You need to replace "${filename}" with the actual name of the file you want to work on.

When you run this command, it will take the specified file and replace all tab characters with the desired number of spaces specified by ${number} within the file. This can be useful for standardizing the indentation of a file or converting tabs to spaces in a consistent manner.