Earlier, I wrote “:for loops are a strange beast so I will elaborate on those in a separate post.” so now is the time to do that.
The :for loop documentation is very dense:
Command Syntax Description for :for <var> from=<int> to=<int> step=<int> do={ <commands> }execute commands over a given number of iterations
So a for loop has these elements:
- from=
- to=
- step=
- do=
Luckily, the old RouterOS 2.7 documentation on loops (which they’ve revamped after Router OS 2.7 removing many useful examples) has this:
:for – It has one unnamed argument, the name of the loop variable. from argument is the starting value for the loop counter, tovalue is the final value. This command counts loop variable up or down starting at from and ending with to, inclusive, and for each value it executes the do statement. It is possible to change the increment from the default 1 (or -1), by specifying the stepargument.
[admin@MikroTik] > :for i from=1 to=100 step=37 do={:put ($i . " - " . 1000/$i)} 1 - 1000 38 - 26 75 - 13 [admin@MikroTik] >
You might think that from= the start value, to= the finish value and the loop won’t execute when step= a positive value and from= larger than to=. Or that without a step= the loop will always iterate in ascending order.
Wrong! And wrong!
So it’s time for some…
