Shell flow control statements

Conditional statement if-then Structure

If [condition]
Then
Commands
Fi

Note: To put then and if in the same row, you need to write the following:If [condition]; thenIn shell.

In addition,There must be a space between [] and condition !!!For more information about condition, see here.

If-then-else Structure

If [condition]
Then
True-Commands
Else
False-Commands
Fi

If-then-Elif Structure

If [condition_1]
Then
Commands_1
Elif [condition_2]
Then
Commands_2
Elif [condition_3]
Then
Commands_3
...
...
Else
Commnads_n
Fi

Loop statement for loop: For-in-done Structure

For variable in list-of-Values
Do
Commands
Done

While loop: While-do-done Structure

While [condition]
Do
Commands
Done

Until loop: Until-do-done Structure

Until [condition]
Do
Commands
Done