Date: Mon, 24 Jul 1995 08:12:45 +0200 (MET DST) From: J Wunsch <j@uriah.heep.sax.de> To: freebsd-hackers@freebsd.org (FreeBSD hackers) Subject: Re: your mail Message-ID: <199507240612.IAA04053@uriah.heep.sax.de> In-Reply-To: <199507240139.LAA29063@godzilla.zeta.org.au> from "Bruce Evans" at Jul 24, 95 11:39:30 am
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As Bruce Evans wrote:
>
> >4.4BSD sed is broken. You must quote '/'in brackets,
> >eg. sed -e 's/.*[\/]//'
...which would have been equivalent to
sed -e 's/.*\///'
Anyway, FreeBSD 1.1.5.1's sed has been broken for this and didn't
recognize the escaped second slash.
I'm not sure if 4.4BSD's sed is *broken*. I've studied Posix 1003.2
up and down, and it has been not clear if the regexp delimiters should
have higher or lower precedence than brackets. I think the behaviour
of this sed is strange, but not violating Posix (unlike the Net-2 sed,
escaping the regexp delimiter is required to work).
> Is this portable? I thought that '\' isn't special in brackets. It isn't
> needed even to quote ']' - you can put the ']' first so that it isn't
> interpreted as the end of the brackets:
I'm not sure. I've replaced the Internet Info CD in my drive with the
newly-arrived 2.0.5 `live filesystem' as a replacement for my missing
/usr/src yesterday, so i cannot look into 1003.2 right now. I think
backslashes are special, and you're supposed to escape at least
backslashes themselves.
I think this one should also apply for [] groups, explaining the need
for backslashes under some circumstances:
2. The escape sequence \n matches a newline character embedded in the
pattern space. You can't, however, use a literal newline character
in an address or in the substitute command.
You are right, ranges including a `]' are impossible, as well as ranges
including a hyphen. See re_format(7).
--
cheers, J"org
joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/
Never trust an operating system you don't have sources for. ;-)
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