In programming, a loop statement is a control structure used to repeat the execution of a set of instructions multiple times until a certain condition is met.

The while loop

The while loop is used to execute a set of instructions specified between the do and done keywords, for as long as the condition remains true.

while [[ condition ]];do  instructionsdone

This structure is often used to create long-running processes or to process data of unknown length.

Note: In programming, the cycle in which a loop executes its instructions — whether partially or completely — is called an iteration. For example, if a loop executes the specified instructions 3 times, we'll say that it performed 3 iterations.

Example

Let's consider this script, that outputs the elements of an array of strings:

#!/bin/bashguests=("John Doe" "James Higgins" "Alice Peterson")total=${#guests[@]}index=0