Loops and Iterations
Here is an example of a loop that will repeat some action until a condition is met:
number=0 while [ $number -lt 10 ]; do echo "Number = $number" number=$((number + 1)) done echo "Finished!" This produces:
Number = 0 Number = 1 Number = 2 Number = 3 Number = 4 Number = 5 Number = 6 Number = 7 Number = 8 Number = 9 Finished!
We assigned the value 0 to the variable
while command expects a
test, in this case whether
$number is less than 10.
The semicolon again breaks the line, and the
do command repeats everything up
done command until the
while condition is no longer true.
do loop, we repeat, or iterate, two lines. The first echoes the
number, and the second adds one to it. When
$number reaches 10, it is no longer
less than 10, the condition is false, and the
do loop quits. The program goes
on to the next line.