Date: Mon, 02 Sep 2013 17:54:11 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: FreeBSD Current <freebsd-current@FreeBSD.org>, freebsd-standards@FreeBSD.org Subject: bug with special bracket expressions in regular expressions Message-ID: <5224A693.3000904@FreeBSD.org>
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re_format(7) says:
There are two special cases‡ of bracket expressions: the bracket expres‐
sions ‘[[:<:]]’ and ‘[[:>:]]’ match the null string at the beginning and
end of a word respectively. A word is defined as a sequence of word
characters which is neither preceded nor followed by word characters. A
word character is an alnum character (as defined by ctype(3)) or an
underscore. This is an extension, compatible with but not specified by
IEEE Std 1003.2 (“POSIX.2”), and should be used with caution in software
intended to be portable to other systems.
However I observe the following:
$ echo "cd0 cd1 xx" | sed 's/cd[0-9][^ ]* *//g'
xx
$ echo "cd0 cd1 xx" | sed 's/[[:<:]]cd[0-9][^ ]* *//g'
cd1 xx
In my opinion '[[:<:]]' should not affect how the pattern is matched in this case.
Any thoughts, suggestions?
Thank you!
--
Andriy Gapon
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