Switching case

Apart from simple branches with if, it is also possible to process multiple decision-making operations using the case command. In a case statement, the expression contained in a variable is compared with a number of expressions, and for each expression matched, a command is executed.

It is possible to have multiple branching using the if/elif/else commands. But if more than two or three elif commands are used, then code becomes very complex. When all the different conditions are depending on a single variable, in such cases, the esac statement is used. The interpreter checks the value of the case variable against value1, value2, value3, and so on, till the match is found. If the value is matched then all the statements after that case value are executed till the double semicolon is reached. If nothing is matched then statements after esac are executed. Wildcard characters and pipe (vertical bar for ORing two values) are allowed in the case statement.

A case statement has the...