Date: Thu, 2 Feb 2012 01:51:56 -0600 (CST) From: Robert Bonomi <bonomi@mail.r-bonomi.com> To: freebsd-questions@freebsd.org Subject: Re: some kind of binary sed(1) command Message-ID: <201202020751.q127puMO011247@mail.r-bonomi.com> In-Reply-To: <20120202062236.GA3419@tinyCurrent>
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> From owner-freebsd-questions@freebsd.org Thu Feb 2 00:27:33 2012
> Date: Thu, 2 Feb 2012 07:22:36 +0100
> From: Matthias Apitz <guru@unixarea.de>
> To: freebsd-questions@freebsd.org
> Subject: some kind of binary sed(1) command
>
>
> Hello,
>
> I have a normal ASCII file wich has in some places two lines of '*',
> separated by an empty line, i.e.
>
> ....\n
> *********************\n
> \n
> *********************\n
> ....\n
>
> and I want to substitute the \n between the star lines by \f; the
> 'binary' sed command would just be
>
> s/*****\n\n*****/*****\n\f*****/
>
> which ofc does not work with sed(1) because it is line oriented;
> I could write something in perl, C, awk or whatever language, but I
> would prefer to do it with the normal commands... any ideas?
<lightbulb mode="on">
Use sed.
</lightbulb>
*GRIN*
As follows:
sed -e ' t l
:l
/^[*]+$/ {
N
!/\n$/ {
P
s/^.*\n//
t l
}
/\n$/ {
N
!/\n\n[*]*$/ {
P
s/^.*\n//
P
s/^.*\n//
t l
}
/\n\n[*]*$/ s/\n\n/\n\f/
}
}'
Note: "how" this incantation works is left as an excercise for the student.
Careful perusal of the FM will provide enlightenment.
Caveat: this will convert:
{stars}
{blank}
{stars}
{blank}
{stars}
to;
{stars}
{formfeed}
{stars}
{blank}
{stars}
not:
{stars}
{formfeed}
{stars}
{formfeed}
{stars}
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