todo

[node] Run and understand. Execute functions in external packages with the node command

[npm] Run and understand. Execute default script with npm command

[shell script] Run and understand. Execute shell script within script

[trap] Run and understand. Execute error processing with the trap command

[shellscript] Run and understand. Receive the results of a shellscript

[source] Run and understand. Loading shellscript within shellscript

[find] Run and understand. Use the path output by the find command in other commands

[cut] Run and understand. Split and display strings in a file with the cut command

[chsh] Run and understand. Change the default shell with the chsh command

[chown] Run and understand. Change user and group of a file with the chown command