du:tldr:87c2b

This command is used to estimate and display the disk usage of a particular directory.

Here's a breakdown of each part of the command:

• du: Stands for "disk usage", it is a command-line utility in Unix/Linux systems used to determine the disk usage of files and directories.
• -: This is an option (or flag) used to specify additional behavior for the du command. In this case, the actual option is not mentioned so the behavior will depend on the value given for ${select}.
• ${select}: Here, ${select} is a placeholder that represents a variable. It is not an actual part of the command. The value of this variable is expected to be specified by the user when running the command. The value provided for ${select} will determine the behavior of the du command for the specified directory.
• ${path-to-directory}: Similar to ${select}, ${path-to-directory} is another placeholder representing a variable. It also needs to be replaced with an actual directory path when executing the command. This variable represents the path to the directory for which you want to estimate the disk usage.

So, if you were to use the command like du -${select} ${path-to-directory}, you would replace ${select} with an appropriate option (or value) and ${path-to-directory} with the actual path to the desired directory.