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Until Loops: Repeat Until True

Until loops repeat until condition is true. Opposite of while.

Here's the thing: Until loops are like while, but inverted. Use them when it makes sense.

Basic Syntax​

until [ condition ]; do
    # commands
done

My take: Until repeats until true. Opposite of while.

Common Patterns​

Wait For Service​

until systemctl is-active nginx; do
    echo "Waiting for nginx..."
    sleep 1
done

My take: Until is good for waiting. Use it.

Retry Until Success​

until curl -f http://example.com; do
    echo "Retrying..."
    sleep 5
done

When to Use​

Use until when:

  • Waiting for something
  • Retrying until success
  • Inverted logic makes sense

Use while when:

  • Repeating while true
  • Normal iteration
  • Standard loops

My take: Use until when it makes sense. While is more common.

What's Next?​

Now that you understand until loops, let's talk about Break And Continue.

Personal note: Until loops seemed unnecessary at first. Then I used them for waiting. Now I use them when they fit. They're useful. Learn them.