When I was writing the applet that should stop accidental scheduled router reloads, I wanted to use the action string match command to perform pattern matching on the output of the show reload command. Somehow the applet didn’t want to work as expected, so I checked the documentation on Cisco’s web site.

Reading the command description, I should have realized the whole thing must be broken. It looks like the documentation writer was fast asleep; even someone with a major in classical philosophy and zero exposure to networking should be able to spot the glaring logical inconsistencies.

Judging by the quality of the documentation, I started wondering if someone mixed up the order of parameters, so I swapped the pattern and the string. No luck. Totally fed up, I spent 30 seconds cut-and-pasting together a short test case:

event manager applet CheckMatchCommand
 event none
 action 1.0 string match "a" "a"
 action 1.1 puts "match: -a- versus -a- result: $_string_result"
 action 2.0 string match "aa" "a"
 action 2.1 puts "match: -aa- versus -a- result: $_string_result"
 action 3.0 string match "a" "aa"
 action 3.1 puts "match: -a- versus -aa- result: $_string_result"
 action 4.0 string match "a." "aa"
 action 4.1 puts "match: -a.- versus -aa- result: $_string_result"
 action 5.0 string match "aa" "a."
 action 5.1 puts "match: -aa- versus -a.- result: $_string_result"
 action 6.0 string match "." "a"
 action 6.1 puts "match: -.- versus -a- result: $_string_result"
 action 7.0 string match "a" "."
 action 7.1 puts "match: -a- versus -.- result: $_string_result"

Here are the results:

EEM#show version | inc IOS Software
Cisco IOS Software, 7200 Software (C7200-ADVIPSERVICESK9-M), Version 15.0(1)M4
EEM#event man run CheckMatchCommand
match: -a- versus -a- result: 1
match: -aa- versus -a- result: 0
match: -a- versus -aa- result: 0
match: -a.- versus -aa- result: 0
match: -aa- versus -a.- result: 0
match: -.- versus -a- result: 0
match: -a- versus -.- result: 0

As you can see, the string match command has nothing to do with pattern matching. It’s a simple string comparison, returning 1 if the two strings are equal and 0 if they are not.

Faced with such a huge discrepancy between documentation and actual behavior, one is forced to ask: what was the QA team doing? Did anyone ever test this feature? And last but not least: does this mean that nobody is using EEM 3.0 features or writing EEM applets? EEM 3.0 is almost two years old; such an obvious bug should have been reported and fixed by now.