Thanks. Have learnt a lot from your replies. On Sat, Sep 21, 2019 at 5:34 PM Ilkka Virta <itvi...@iki.fi> wrote:
> On 21.9. 03:12, hk wrote: > > Thanks for the reply. I was wrong in my report. It does match values like > > aab and aaaaaab in its original form. > > In some systems, yes. (It does that on my Debian, but doesn't work at > all on my Mac.) > > > It is syntatically correct as a regular expression. > > [[:space:]]*?(a)b isn't a well-defined POSIX ERE: > > 9.4.6 EREs Matching Multiple Characters > > The behavior of multiple adjacent duplication symbols ( '+', '*', '?', > and intervals) produces undefined results. > > > https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/basedefs/V1_chap09.html > > > -- > Ilkka Virta / itvi...@iki.fi >
