Bash Run While Loop - Shell/Bash

The while loop is a fundamental feature of Shell/Bash programming. It is used to repeat a block of code while a certain condition is true. This allows you to automate tasks and save time.

Syntax

The syntax for a while loop in Shell/Bash programming is as follows:

while [ condition ]
do
    # Code to repeat while condition is true
done

The condition in the square brackets is evaluated each time the loop iterates. If the condition is true, the code inside the do and done statements will be executed. Once the code inside the loop has finished executing, the condition is evaluated again. This continues until the condition is false.

Example

Let's see an example of a while loop in action. The following code prompts the user to enter a number, and then prints the number and increments it by one until it reaches 10:

#!/bin/bash

echo "Enter a number:"
read num

while [ $num -le 10 ]
do
    echo $num
    num=$((num+1))
done

In this example, we first prompt the user to enter a number using the echo and read statements. Then, in the while loop, we check if the value of num is less than or equal to 10. If it is, we print the value of num using the echo statement and then increment it by one using the num=$((num+1)) statement. This process continues until the value of num reaches 11, at which point the while loop terminates.

Conclusion

In conclusion, the while loop is an important feature of Shell/Bash programming that allows you to automate tasks and save time. By understanding the syntax and examples of while loops, you can become a more efficient and effective Shell/Bash programmer.