Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

while

while performs a block of statements as long as a particular condition is true:

while ($x<10) {     print "$x\n";     $x++;}

Remember that the condition can be anything that returns a true or false value. For example, it could be a function call:

while ( InvalidPassword($user, $password) )        {        print "You've entered an invalid password. Please try again.\n";        $password = GetPassword;}