[Toybox] [PATCH] Implement mv -n / cp -n (no clobber).

[Andy Chu]

>> Anecdotally, it seems like a lot of shell script issues are caused by
>> unexpected existing state, but in a lot of cases you don't CARE about
>> the existing state -- you just want a final state (e.g. a bunch of
>> symlinks to toybox).
>
> "ln -sf" actually works pretty predictably. :)

One more nitpick ... ln -sf isn't idempotent for the same reason that
cp isn't.  If you run it more than once you get different results.

I was trying to create a package manager with sandboxed builds, with
the aforementioned linux-user-chroot, and my own tools.  Bootstrapped
all in shell.  All of my ln invocations used -T /
--no-target-directory for this reason.  (At least this flag doesn't
seem to be entangled with other behavior, unlike mkdir and rm).

$ mkdir foo

$ ln -sf foo link; tree --charset=ascii
.
|-- foo
`-- link -> foo

$ ln -sf foo link; tree --charset=ascii
.
|-- foo
|   `-- foo -> foo
`-- link -> foo

Compare with:

$ mkdir foo

$ ln -sf -T foo link; tree --charset=ascii
.
|-- foo
`-- link -> foo

$ ln -sf -T foo link; tree --charset=ascii
.
|-- foo
`-- link -> foo

Andy





Andy

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