while <condition> [loopname <loopname>] "{" ... "}"
The while command executes a block of commands repeatedly, checking the provided condition at the start of each iteration. If the condition is true, the loop executes again. This is similar to a do loop, except that the contents of a while loop may not be executed at all if the iteration criterion tests false upon the first iteration. For example, the following code prints out the low-valued Fibonacci numbers:
i = 1 j = 1 while (j < 50) { print j i = i + j print i j = j + i }