On Mon, 2 Sep 2013, Andriy Gapon wrote:
> 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? there are two simpler expressions, whose difference I don't understand either (tested on 8.4-PRERELEASE) $ echo "cd0 cd1 xx" | sed 's/cd[0-9] //g' xx $ echo "cd0 cd1 xx" | sed 's/[[:<:]]cd[0-9] //g' cd1 xx -- Damian _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
