n:tldr:3e862

The command "n use ${version} ${file-js}" is not a standard Unix command, but it appears to be a command that uses the "n" package manager/tool for managing Node.js versions.

Here's a breakdown of the command:

• "n" is the name of the package manager/tool that is being used.
• "use" is a command or subcommand of the "n" tool that instructs it to use a specific version of Node.js.
• "${version}" is a placeholder that should be replaced with the actual version number of Node.js you want to use. For example, "${version}" could be something like "10.15.3" which represents Node.js version 10.15.3.
• "${file-js}" is another placeholder that should be replaced with the path or name of a JavaScript file that you want to execute using the specified version of Node.js. For example, "${file-js}" could be something like "app.js" which represents a file named "app.js" in the current working directory.

The command instructs the "n" tool to use a specific version of Node.js and then execute a JavaScript file with that version.