BMC Helix Network Management uses regular expressions (regex) in many areas throughout the product. But not all fields accept all regex. This page identifies the acceptable regex for different areas of the product.

Threshold Check Configuration

SUBSTRING field

The Substring field uses a regex rule to check each instance description and determine whether the threshold applies. Use the following rules to understand how the Substring field pattern works:

• Matching is case insensitive.
• If the pattern matches the instance description, the threshold applies.
• If the field is empty, the threshold applies to all instances.
• To exclude instances, use a negative lookahead pattern.

The table below shows examples of how different patterns match instance descriptions:

Pattern	What it matches	Notes
eth0	Any description containing “eth0”	Case insensitive
bandwidth	“Bandwidth on Netreo Core eth0”	Partial match
Latency.*Local	“Round trip Latency for Local1”	Matches “Latency” → any characters → “Local”
(empty)	All instances	No filtering

The table below shows how these patterns exclude certain instances:

Pattern	What it matches	Notes
^(?!.*eth0)	All instances except those containing “eth0”	Excludes eth0
^(?!.*swap)	All instances except those containing “swap”	Excludes swap