netdata_netdata/libnetdata/simple_pattern

Simple patterns

Unix prefers regular expressions. But they are just too hard, too cryptic to use, write and understand.

So, Netdata supports simple patterns.

Simple patterns are a space separated list of words, that can have * as a wildcard. Each word may use any number of *. Simple patterns allow negative matches by prefixing a word with !.

So, pattern = !*bad* * will match anything, except all those that contain the word bad.

Simple patterns are quite powerful: pattern = *foobar* !foo* !*bar * matches everything containing foobar, except strings that start with foo or end with bar.

You can use the Netdata command line to check simple patterns, like this:

# netdata -W simple-pattern '*foobar* !foo* !*bar *' 'hello world'
RESULT: MATCHED - pattern '*foobar* !foo* !*bar *' matches 'hello world'

# netdata -W simple-pattern '*foobar* !foo* !*bar *' 'hello world bar'
RESULT: NOT MATCHED - pattern '*foobar* !foo* !*bar *' does not match 'hello world bar'

# netdata -W simple-pattern '*foobar* !foo* !*bar *' 'hello world foobar'
RESULT: MATCHED - pattern '*foobar* !foo* !*bar *' matches 'hello world foobar'

Netdata stops processing to the first positive or negative match (left to right). If it is not matched by either positive or negative patterns, it is denied at the end.