Date: Thu, 18 Mar 1999 09:48:36 +0000 From: Brian Somers <brian@Awfulhak.org> To: cjclark@home.com Cc: freebsd-questions@FreeBSD.ORG (FreeBSD Questions) Subject: Re: sed and newlines Message-ID: <199903180948.JAA10316@keep.lan.Awfulhak.org> In-Reply-To: Your message of "Wed, 17 Mar 1999 18:39:00 EST." <199903172339.SAA06674@cc942873-a.ewndsr1.nj.home.com>
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> The sed manpage says,
>
> Sed Regular Expressions
> The sed regular expressions are basic regular expressions (BRE's, see
> regex(3) for more information). In addition, sed has the following two
> additions to BRE's:
> .
> .
> .
> 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.
>
> If I am reading this correctly,
>
> % sed 's/\n/ /' file
>
> Should take the file and subsitute three spaces in place of every
> newline. However, it does not. It does not seem to understand '\n.'
>
> In spite of what it says, I have tried literal newlines (with \ and
> ^V), and as claimed on the manpage, it does not work (it will
> generate errors).
>
> Am I missing something obvious? Or is sed broken?
Sed performs commands on each line. A line is read in and the
newline is removed. The command(s) are executed and the pattern
space is output with a trailing newline.
The only time you ever see a newline in the pattern space is if you
put it there yourself (with ``N'' for example).
Something like
sed -e :x -e N -e 's/\n/ /' -e '$p' -e 'b x'
will work, but it's not the most elegant way as it ends up buffering
your entire file. The ``tr'' command is probably more appropriate
for this sort of thing.
> Thanks.
> --
> Crist J. Clark cjclark@home.com
--
Brian <brian@Awfulhak.org> <brian@FreeBSD.org> <brian@OpenBSD.org>
<http://www.Awfulhak.org>;
Don't _EVER_ lose your sense of humour !
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