Eric Blake wrote:
>>> cp [-Pfip] source_file target_file
>> Thanks for the clarification. So POSIX mandates all of -fin are allowed,
>> the last taking precedence. I presume it also means warnings should not be
>> printed.
>
> No, POSIX only mandates -fi. -n is an extension, so we can make it
> behave however we'd like (although consistent behavior goes a long way).
>
>> In any case I think the `mv` descriptions should we reworded to something
>> like:
>>
>> -f rename a file even if the destination is present and not writable
>> (overrides any previous -i or -n option).
>
> Not quite. -f and -i do not override each other. Per POSIX, they
> affect independent code paths, such that:
>
> cp
> cp -f
> cp -i
> cp -f -i (also spelled cp -i -f)
>
> have four different behaviors.
OK I had missed the asymmetry between the
-f options of mv and cp.
The descriptions in Kamil's patch look correct so.
For my own reference this is how I now see
the overwrite characteristics of cp & mv:
cp : default overwrite method = truncate only (file must be writable)
-f overwrite method = truncate falling back to unlink+create
(redundant if the -n option is used)
--remove-destination
overwrite method = unlink+create
(redundant if the -n option is used)
-i prompt before trying to overwrite dest
(overrides any preceeding -n option)
-n never overwrite
(overrides any preceeding -i option)
mv : prompt to overwrite if dest not writable
-f never prompt before overwriting
(overrides any preceeding -i or -n options)
-i always prompt before overwriting
(overrides any preceeding -f or -n options)
-n never overwrite
(overrides any preceeding -f or -i options)
p.s. According to the FreeBSD manpages referenced in this thread,
cp -f in FreeBSD doesn't conform to POSIX, and instead
means as I originally thought: "try best to overwrite _and don't prompt_."
I.E. it overrides any preceeding -i or -n options.
cheers,
Pádraig.
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