[Feature Request] check output from command

[antedebaas]

I'd love a action type where i can just call a command and check if a value matches a certain output.
there are 2 use cases i would like to implement:

1. check logged in users count (eg. get a number and see if its greater than 0 in this case)
2. check if the command output contains a certain phrase

the first one is a count difference check, maybe a max_good and min_good value would be generic enough to make it into a check.
anything outside that range could be considered bad.

in the second one i would love a sub-string or regex matching so i just have to check if a certain content is present in the output and if not result in a bad state.

both could make use of the invert flag on the alarms inverting the good and bad states making it more usable.
let me know what you think about this.