yar at comp.chem.msu.su
Tue Mar 27 07:59:46 UTC 2007
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?
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
I.e., each file preserves its individuality. This can be at logical
conflict with cumulative addresses across all files.
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