fswatch:tldr:d1ad2

This command involves the usage of multiple commands in a pipeline. Let's break it down step by step:

1. fswatch is a command-line utility used for monitoring changes in a directory. It can detect events like file creation, modification, deletion, etc. The --event option specifies the type of event you want to monitor. In this command, ${select} is a variable that represents the desired event to watch for.

2. ${path-to-directory} is another variable that represents the path of the directory you want to monitor.

3. The | symbol is a pipe that redirects the output of the previous command to the input of the next command.

4. xargs -n 1 is a command used to build and execute commands from standard input. The -n 1 option tells xargs to execute the following command once for each item received.

5. ${bash_command} is a variable that represents the command you want to execute for each detected event. This can be any valid shell command or a custom script.

So, in summary, this command sets up a file system watcher (fswatch) to monitor a specific type of event (${select}) in a given directory (${path-to-directory}). Whenever an event occurs, the output is passed to xargs, which then executes the specified ${bash_command} for each event detected.