Re: Does --newer work for -x?

[Scott Wheeler <scott@directededge.com>]

> On Dec 31, 2016, at 01:38, Colin Percival <cperciva@tarsnap.com> wrote:
> 
> On 12/30/16 15:53, Scott Wheeler wrote:
>>> On Dec 31, 2016, at 00:29, Graham Percival <gperciva@tarsnap.com> wrote:
>>> On Sat, Dec 31, 2016 at 12:19:09AM +0100, Scott Wheeler wrote:
>>>> bela: /tmp/foo> sudo tarsnap -xvf test --newer "Jan 1, 2016"
>>> 
>>> --newer is only specified for working with -c:
>> 
>> Ah, odd, missed that when scanning the docs. [...]
> 
> Hmm, the code which checks options for validity thinks they're ok in [cxt] modes (bsdtar.c):

[...]

> 
> So I think the man page is wrong here.
> 
> As for the precise formats accepted... this is some very historical
> date/time parsing code, so I'd assume that "201601010000" would be
> parsed as the start of January 1, 2016 (see `touch -t`).  Looking at
> the code, it's clear that a variety of other formats can be parsed;
> but I don't think the exact set is documented anywhere...

I poked a bit into the get_date() implementation before posting, but it looked like it should parse a number of formats, none of which seemed to work.

Unfortunately, the scheme you suggested doesn't either.  This is with the same test case I posted earlier (one empty file in one dir, created with `touch` earlier today):

bela: /tmp/foo> sudo tarsnap -xvf test --newer "201601010000"
x test/
x test/foo
bela: /tmp/foo> sudo tarsnap -xvf test --newer "201701010000"
x test/
x test/foo

> (BTW, for your exact use case I think the --keep-newer option might
> do what you want much far less aggravation?)

Hmm, yes, I interpreted that option too literally.  I assumed it would only keep files that were newer, not newer or the same age.  Maybe an alias is in order?  --only-updated-files?  --only-new?  (The latter is perhaps confusing as it'd seem to imply only files that were new to that archive.)

One quirk here is that it exits non-zero when doing exactly what I've instructed it to do:

bela: /tmp/foo> sudo tarsnap -xvf test --keep-newer
x test/
x test/foo: File on disk is not older; skipping.
tarsnap: Error exit delayed from previous errors.
bela: /tmp/foo> echo $?
1

Printing an error message (not just a notice to stderr) and exiting with a non-zero code seems incorrect for something that is explicitly expected to happen.

-Scott

--
Scott Wheeler | Co-founder | Directed Edge | www.directededge.com | @directededge