Re: sed -i

On Mon, Mar 26, 2007 at 08:57:14PM +0530, Joseph Koshy wrote:
Recently noticed that our sed(1) differs from its GNU
analog in that in -i mode it considers all files as a
single sequence of lines while the latter treats each file
independently. The in-line mode isn't in POSIX, so it isn't
really clear which way is correct.

Aren't sed's addresses required to be cumulative across its
input files?

http://www.opengroup.org/onlinepubs/009695399/utilities/sed.html

That makes sense for filter mode because it's equvalent to
concatenating the files in advance:

cat files ... | sed expression

OTOH, in-place mode selected by a -i option can be seen as follows:

for f in files ...; do
sed expression < $f > $f.tmp && mv $f $f.bak && mv $f.tmp $f
done

I.e., each file preserves its individuality. This can be at logical
conflict with cumulative addresses across all files.

--
Yar
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