unexpand:tldr:c169f

The command "unexpand -a ${filename}" is used to convert spaces in a file to tabs.

Here's a breakdown of the command:

• "unexpand" is the name of the command. It is used to modify the spacing in a file.
• "-a" is an option or flag used along with the "unexpand" command. In this case, it tells the command to convert all occurrences of spaces to tabs.
• "${filename}" is a placeholder that represents the name of the file you want to modify. You should replace it with the actual file name or path.

So when you run this command, the "unexpand" utility will read the specified file and replace all spaces with tabs according to the "-a" option. This can be useful when you want to convert files with space indentation to tab indentation for better readability or consistency in coding.