In Bash, the until loop is similar to the while loop, but it repeatedly executes a block of code as long as a condition is false. It is useful when you want to execute a loop until a particular condition becomes true. Here’s the basic syntax of an until loop in Bash:
until [ condition ]; do
# Code to execute
done
The loop continues executing the code block as long as the condition remains false. Once the condition becomes true, the loop terminates, and the program execution continues with the next statement after the loop.
Here’s an example that demonstrates the usage of an until loop in Bash:
#!/bin/bash
count=1
until [ $count -gt 5 ]; do
echo "Count: $count"
((count++))
done
In this example, the until loop starts with an initial value of count set to 1. The condition [ $count -gt 5 ] checks if the value of count is greater than 5. Since the initial value of count is not greater than 5, the loop executes the code block, which consists of printing the value of count and incrementing it by 1 using ((count++)).
When you run this script, it will output:
Count: 1
Count: 2
Count: 3
Count: 4
Count: 5
The loop iterates five times, printing the value of count from 1 to 5, similar to the while loop example.
The until loop can be handy when you want to execute a block of code until a specific condition becomes true. You can modify the condition inside the until loop to suit your specific needs and control the loop based on your requirements.