Control flow Structure

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1.if then Else statement

If condition 1

Then command 1

Elif Condition 2

Then command 2

else Command 3

Fi

If statements must be terminated with the word fi, elif and else are optional.

Simple If statement: if condition

Then command

Fi

When using the IF statement, then must be on a new line, otherwise an error is generated, and if no branch, the command delimiter must be used:

if condition; then

Command

Fi

2.if conditions

Then

Command 1

Else

Command 2

Fi

3.null command

The IF statement parts cannot be empty--some statements can already do so. To solve this problem, the shell provides: null command. Empty commands are always true.

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Control flow Structure