2011/12/22 Bruce Korb <bkorb@gnu.org>
>
> When the exact opposite is the useful variation?  I.e. keep-on-failure.
> "-i" for sed is simple, understandable and implemented a lot.
>

As far as I know, -i is only implemented with GNU sed and BSD sed, and they
are incompatible, BSD sed's -i takes a mandatory argument, while GNU sed's
-i takes an optional string which must be provided in the same argument.
E.g.

gnused -i.bak sed-script file
bsdsed -i .bak sed-script file

So the only portable way of using sed to "edit" (read: overwrite) a file is
with

sed sed-script file > file.tmp && mv file.tmp file

I'd welcome this >; syntax.

-- 
Geir Hauge