I want to extract the content after the :, but there can be only one :.

Examples:

foo:bar             # match, extract 'bar'
foo:123             # match, extract '123'

foo:bar:123         # do not match

So that last example should not match because it has multiple :.

I tried a negative lookbehind ^. (?<!:):(. )$ but that nonetheless matches and extracts from that last example.

Here's a demo.

CodePudding user response：

Try (regex101):

^[^:] :([^:] )$

This will match only lines with one : and get the string after the :