source is 1234567890, the regular expression ((?<=\d)\d{3})*\b can match: 234567890, so i think sed should replace 234567890 with TEST, but the result is: 1234567890, why?
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问题:
回答1:
look-behind is not supported by sed. you could try ssed (super sed), it supports perl mode, (-R) then you could pass perl style regex to it. e.g. look ahead/behind.
see the feature list:
https://launchpad.net/ssed
回答2:
You need to rewrite the regex without lookbehind:
s/(\d)(?:\d{3})*\b/\1TEST
