while(1)                                                       while(1)

  while

  NAME

    while - execute commands while a condition is met

  SYNOPSIS

  C shell

    while (expr)
    ...
    end

  Korn shell

    while list do list done

  DESCRIPTION

    This command is a built-in command in the C shell and the Korn shell.

  C shell

    The while(1) command executes the commands between the while and the
    matching end while expr (an expression, as described in the section on
    expressions) evaluates non-zero. The elements while and end must appear
    alone on their input lines. The break(1) and continue(1) commands can be
    used to terminate or continue the loop prematurely. If the input is a
    terminal, the user is prompted the first time through the loop (as with
    foreach(1)).

  Korn shell

    A while is a prechecked loop. Its body is executed as often as the exit
    status of the first list is zero. The exit status of a while statement is
    the last exit status of the list in the body of the loop. If the body is
    not executed, the exit status is zero.