tar or gzip dry run?

jellybean stonerfish wrote:
> You could pipe the stdout of tar to a command to count characters. There
> is no reason
>
> tar --gzip --create --file - directory | wc -c
>
I assume you meant to add "[..] wouldn't work" And you are so right!

I did not know about the wc tool, and I did not find the information how
to redirect tar output to stdout. You covered both

Thanks a lot!

Lars

jellybean stonerfish wrote:
> You could pipe the stdout of tar to a command to count characters. There
> is no reason
> tar --gzip --create --file - directory | wc -c

Lars Uffmann <aral DeleteThis @nurfuerspam.de> wrote:
> I assume you meant to add "[..] wouldn't work" And you are so right!

It looks like there may be some sarcasm there. I'm not entirely sure
why, because jellybean stonerfish's suggestion works perfectly. At least
for me:

$ tar --gzip --create --file - /boot | wc -c
tar: Removing leading `/' from member names
37972847
$

So, archiving /boot on my system would require approximately 38MB.

I must admit that, personally, I'd have used the older flags and done
it this way, but the effect is exactly the same:

$ tar czf - /boot | wc -c

Chris

On Tue, 28 Jul 2009 22:38:18 +0100, Chris Davies wrote:

> jellybean stonerfish wrote:
>> You could pipe the stdout of tar to a command to count characters.
>> There is no reason
>> tar --gzip --create --file - directory | wc -c
>
> Lars Uffmann <aral.RemoveThis@nurfuerspam.de> wrote:
>> I assume you meant to add "[..] wouldn't work" And you are so right!

I remember trying to say that tar would have to read everything with this
method, and there is probably a better way, but decided to make my post
short. I don't have a clue where the string "There is no reason" came
from. I don't remember typing that.

>
> It looks like there may be some sarcasm there. I'm not entirely sure
> why, because jellybean stonerfish's suggestion works perfectly. At least
> for me:
>
> $ tar --gzip --create --file - /boot | wc -c tar: Removing leading
> `/' from member names 37972847
> $
>
> So, archiving /boot on my system would require approximately 38MB.
>
> I must admit that, personally, I'd have used the older flags and done it
> this way, but the effect is exactly the same:
>
> $ tar czf - /boot | wc -c
>
> Chris

I tested it with "-czf -" and use that style of options myself. I posted
the long options to be pedantic.

Chris Davies wrote:
>> You could pipe the stdout of tar to a command to count characters. There
>> is no reason
>> tar --gzip --create --file - directory | wc -c
>
> Lars Uffmann <aral.DeleteThis@nurfuerspam.de> wrote:
>> I assume you meant to add "[..] wouldn't work" And you are so right!
>
> It looks like there may be some sarcasm there.

Nope, I was serious - I was completing the sentence from above the
suggestion

jellybean stonerfish wrote:
> I remember trying to say that tar would have to read everything with this
> method, and there is probably a better way, but decided to make my post
> short.
Actually I wouldn't know how there could be a better way - gzip doesn't
really know the filesize it will reach by compressing until it has
processed the whole data, I guess...

> I don't have a clue where the string "There is no reason" came from. I don't remember typing that.

OMG, it's gotta be *them*! Watch out, they are everywhere

> I tested it with "-czf -" and use that style of options myself. I posted
> the long options to be pedantic.

Actually, as a friend pointed out, -f - is merely giving the --file
option it's default value. So
# tar -cz * | wc -c
works just as fine. Glad to have such a steep learning curve still -
maybe I'm not so old yet after all ^^

Thanks again for your help, it was your solution (with -czf) that I
implemented to get things working last night - a neat little backup
script which has big room for improvement, but I will work on that
tomorrow...

Best Regards,

Lars

Lars Uffmann wrote:
> option it's default value. So
^^^^
its! I meant to type its!

On Wed, 29 Jul 2009 19:46:35 +0200, Lars Uffmann wrote:

> Lars Uffmann wrote:
>> option it's default value. So
> ^^^^
> its! I meant to type its!

If it belongs to it, it is it's, if you have a more than one it, it is
its, and if it belongs to more than one it, it is its'.

jellybean stonerfish wrote:
>> Lars Uffmann wrote:
>>> option it's default value. So
>> ^^^^
>> its! I meant to type its!
> If it belongs to it, it is it's, if you have a more than one it, it is
> its, and if it belongs to more than one it, it is its'.

I was trying to differ from "it is"... but yes I guess in genitive case,
it's also "it's"...

Lars Uffmann <aral.DeleteThis@nurfuerspam.de> wrote:
> Actually, as a friend pointed out, -f - is merely giving the --file
> option it's default value. So

That's only true for certain instances of default. By providing the "-"
explicitly you guarantee the tar will (more probably) do what you expect.

Chris

Chris Davies wrote:
> That's only true for certain instances of default. By providing the "-"
> explicitly you guarantee the tar will (more probably) do what you expect.

(back from a business trip, sorry for the late reply) Could you
elaborate on "certain instances of default"? Otoh I did a little math
and found out I'll probably need to do a different approach since a
whole tgz archive creation will need many hours for ~ 500GB - and I
probably cannot afford to zip it all up for the backup, much less do
that twice, only to know how much disk space is needed.

I might just do an unpacked backup, that will give me a good idea of how
much disk space I need and I'll be fine as long as my backup media are
big enough...

Best Regards and thanks for your help!

Lars