Re: '>;' redirection operator [was: [1003.1(2008)/Issue 7 0000530]: Support in-place editing in sed (-iEXTENSION)]

[Bruce Korb <bkorb@xxxxxxx>]

On 12/22/11 13:03, Eric Blake wrote:
> I assume on the ksh implementation that the temp file is discarded if
> the command (simple or compound) feeding the redirection failed?

One would hope!

>  If the
> redirection is used on a simple command, is there any shorthand for
> specifying that the destination name on success also be fed as an
> argument to the command, to avoid the redundancy of having to type
> 'file' both before and after the'>;' operator?

Doesn't the shell already have enough hieroglyphs?  It is what
intimidates many folks from figuring it out.

>  I assume that this is
> like any other redirection operator, where an optional fd number can be
> prepended, as in '2>; file' to collect stderr and overwrite file on
> success?

When the exact opposite is the useful variation?  I.e. keep-on-failure.
"-i" for sed is simple, understandable and implemented a lot.
Please don't add another glyph to the standardized shell.  Let us not
slide on slippery slopes.  Shells can always add some useful builtins:

   sh_move_if_changed
   sh_save_on_success
   sh_save_on_failure

to cope with this stuff.  Or you can write your own such library for
your own use.  ">;" is not an answer for sed-as-a-batch-editor anyway,
which is what "-i" really is.