Use a negative zero-width lookahead assertion:

perl -E '$x="test: 111\ntest: 222 test: 333"; $x=~/test:\s+(\d{3})(?!t
+est:\s+\d{3})$/s; say $1';
333

[download]

What the

/test:\s+(\d{3})(?!test:\s+\d{3})$/s

regex does is looks for test:, and captures the following three digits, so long as there's not another test: NNN anywhere else after it (meaning the last one in the string). The /s modifier allows you to search across newlines. I've used \s+ instead of a literal space just to ensure that it'll match any type of whitespace (tab, multiple consecutive spaces etc).

In reply to Re: Match only last occurrence by stevieb
in thread Match only last occurrence by sotona

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