Quotation on a Linux system can be a source of confusion at first. Single quotes
' and double quotes
" are treated differently in Bash, and you will need to know the difference if you are writing a Bash script.
ACPI is the acronym for Advanced Configuration and Power Interface; as a standard, it was first implemented in the year 1996, as a successor to APM (Advanced Power Management). As a main feature, it brought the ability to handle power management at the operating system level, whereas before it was handled in BIOS. Some ACPI events on Linux are, by default, handled via systemd-logind, but more complex configurations can be achieved by installing and running the acpid service.