What does esac mean?

What does esac mean?

 

Some people who have just been familiar with Bash programming are always very strange about some keywords in Bash. They know its functions, but they don't know why to write them like this. For example:

 

#! /Bin/bash

 

If [! -N "$1"]

Then

Echo "Usage: $0 [insert | remove]";

Exit 1

Fi

 

Action = "$1"

Case $ action in

Insert) echo "device inserted .";;

Remove) echo "device removed .";;

*) Echo "invalid option .";;

Esac

 

FI is the end of the IF statement, and esac is the end of the case statement. Isn't the keyword like Fi and esac weird? Oh, think about it for a moment. I don't blame it at all. Consider {} [] and so on. {And} are vertical axial symmetry, and [and] are vertical axial symmetry. Now, if, Fi, case, and esac are the same? They are reversed, indicating start and end respectively.