converting .zip to .tar.gz or to .tar.bz2

I saw a post on ubuntuforums about converting a zip file to tar.gz and
thought to myself that it should easily be accomplished on the command
line. After all, "zip -p" unzips to stdout and "tar -czvf -" compresses
from stdin, so they need only be spliced together with a pipe.

But I can't seem to figure it out. I keep getting back empty archives.
(The .tar.gz file, not the original .zip.)

I tried:

unzip -p Qb45.zip | tar -cjvf - Qb45.tar.bz2
unzip -p Qb45.zip | tar -cjvf Qb45.tar.bz2 -
unzip -p Qb45.zip | tar -cvf - | bzip2 > Qb45.tar.bz2

I obviously don't understand precisely what tar or gzip is doing with
the piped data. What am I not doing?

Thank you.

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Michael DeBusk <chinos6398@mypacks.net> writes:

>I saw a post on ubuntuforums about converting a zip file to tar.gz and
>thought to myself that it should easily be accomplished on the command
>line. After all, "zip -p" unzips to stdout and "tar -czvf -" compresses
>from stdin, so they need only be spliced together with a pipe.

>But I can't seem to figure it out. I keep getting back empty archives.
>(The .tar.gz file, not the original .zip.)

>I tried:

>unzip -p Qb45.zip | tar -cjvf - Qb45.tar.bz2
>unzip -p Qb45.zip | tar -cjvf Qb45.tar.bz2 -
>unzip -p Qb45.zip | tar -cvf - | bzip2 > Qb45.tar.bz2

>I obviously don't understand precisely what tar or gzip is doing with
>the piped data. What am I not doing?

a) you are confused about the tar syntax. under -c option, the -f filename
is the OUTPUT filename, not the input filename.
Thus your first and third options are just wrong.

b) unzip -p sends only the file data, not the filenames, etc to stdout. Ie,
tar gets a stream of junk and it has no idea what to call that file.

Just unzip into a directory

mkdir /tmp/unzip
cd /tmp/unzip
unzip /location/of/the/zip/filename.zip
tar -cjf /location/of/theQb45.tar.bz2 *

On Wed, 08 Aug 2007 05:49:49 -0000, Michael DeBusk
<chinos6398@mypacks.net> wrote:
>
>
> I saw a post on ubuntuforums about converting a zip file to tar.gz and
> thought to myself that it should easily be accomplished on the command
> line. After all, "zip -p" unzips to stdout and "tar -czvf -" compresses
> from stdin, so they need only be spliced together with a pipe.
>
> But I can't seem to figure it out. I keep getting back empty archives.
> (The .tar.gz file, not the original .zip.)
>
> I tried:
>
> unzip -p Qb45.zip | tar -cjvf - Qb45.tar.bz2
> unzip -p Qb45.zip | tar -cjvf Qb45.tar.bz2 -
> unzip -p Qb45.zip | tar -cvf - | bzip2 > Qb45.tar.bz2
>
> I obviously don't understand precisely what tar or gzip is doing with
> the piped data. What am I not doing?
>
> Thank you.
>
If the zip archive contains more than one file, you must extract it to a
directory and then tar the directory. If the archive contains only one
file, you can extract it to standard output and pipe it to gzip or
bzip2 without tar.


--
"Why should we subsidize intellectual curiosity?"
-- Ronald Reagan

Bill Marcum wrote:
>
.... snip ...
>
> If the zip archive contains more than one file, you must extract
> it to a directory and then tar the directory. If the archive
> contains only one file, you can extract it to standard output and
> pipe it to gzip or bzip2 without tar.

Which illustrates nicely why I consider zip to be more useful than
tarring and gzipping. Zip keeps multiple files easily accessible,
without going through a (possibly) long extraction and write, and
consumption of untold disk space. The penalty is a very slight
decrease in compression.

--
Chuck F (cbfalconer at maineline dot net)
Available for consulting/temporary embedded and systems.
<http://cbfalconer.home.att.net>



--
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On 2007-08-08, CBFalconer <cbfalconer@yahoo.com> wrote:
> Bill Marcum wrote:
>>
>> If the zip archive contains more than one file, you must extract
>> it to a directory and then tar the directory. If the archive
>> contains only one file, you can extract it to standard output and
>> pipe it to gzip or bzip2 without tar.
>
> Which illustrates nicely why I consider zip to be more useful than
> tarring and gzipping. Zip keeps multiple files easily accessible,
> without going through a (possibly) long extraction and write, and
> consumption of untold disk space.

If you want to extract only certain files from a tar file, it's easy
enough to do. You still have a possibly long read of the file, but you
can certainly avoid the long write and disk use if you know what files
you're looking for. And I don't see how zip gets around that issue,
so I don't see how zip is any more or less useful than tar/gzip.

--keith

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On Wed, 08 Aug 2007 07:36:12 GMT, Unruh <unruh-spam@physics.ubc.ca> wrote:

> a) you are confused about the tar syntax. under -c option, the -f
> filename is the OUTPUT filename, not the input filename. Thus your
> first and third options are just wrong.

No, I understood that the -f filename is the output filename. I got it
wrong because I couldn't figure out how to put the filenames on the
command line. I'm still pretty new at tar and gzip, and at the Linux
command line in general. I'm figuring it out, though, I think.

> b) unzip -p sends only the file data, not the filenames, etc to
> stdout. Ie, tar gets a stream of junk and it has no idea what to call
> that file.

THAT is the problem, then. I was wrong in my original premise. Thanks.

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On Wed, 08 Aug 2007 13:03:34 GMT, Bill Marcum <marcumbill@bellsouth.net> wrote:

> If the zip archive contains more than one file, you must extract it
> to a directory and then tar the directory. If the archive contains
> only one file, you can extract it to standard output and pipe it to
> gzip or bzip2 without tar.

And one would have to know which was the case before starting. :(

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On Wed, 08 Aug 2007 10:35:47 -0400, CBFalconer <cbfalconer@yahoo.com> wrote:

> Which illustrates nicely why I consider zip to be more useful than
> tarring and gzipping. Zip keeps multiple files easily accessible,
> without going through a (possibly) long extraction and write, and
> consumption of untold disk space. The penalty is a very slight
> decrease in compression.

I've been avoiding making that judgement because I've been concerned
that I prefer zip simply because I'm so much more familiar with it.

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Michael DeBusk <chinos6398@mypacks.net> writes:

>On Wed, 08 Aug 2007 07:36:12 GMT, Unruh <unruh-spam@physics.ubc.ca> wrote:

>> a) you are confused about the tar syntax. under -c option, the -f
>> filename is the OUTPUT filename, not the input filename. Thus your
>> first and third options are just wrong.

>No, I understood that the -f filename is the output filename. I got it
>wrong because I couldn't figure out how to put the filenames on the

The filename has to occur IMMEDIATELY after the f.

>command line. I'm still pretty new at tar and gzip, and at the Linux
>command line in general. I'm figuring it out, though, I think.

>> b) unzip -p sends only the file data, not the filenames, etc to
>> stdout. Ie, tar gets a stream of junk and it has no idea what to call
>> that file.

>THAT is the problem, then. I was wrong in my original premise. Thanks.

On Aug 8, 1:37 pm, Michael DeBusk <chinos6...@mypacks.net> wrote:
> On Wed, 08 Aug 2007 07:36:12 GMT, Unruh <unruh-s...@physics.ubc.ca> wrote:
> > a) you are confused about the tar syntax. under -c option, the -f
> > filename is the OUTPUT filename, not the input filename. Thus your
> > first and third options are just wrong.
>
> No, I understood that the -f filename is the output filename. I got it
> wrong because I couldn't figure out how to put the filenames on the
> command line. I'm still pretty new at tar and gzip, and at the Linux
> command line in general. I'm figuring it out, though, I think.
>
> > b) unzip -p sends only the file data, not the filenames, etc to
> > stdout. Ie, tar gets a stream of junk and it has no idea what to call
> > that file.
>
> THAT is the problem, then. I was wrong in my original premise. Thanks.
>
> --
> The "mypacks.net" address from which this message was sent is
> legitimate and not spam-trapped. It is, however, disposable.

Here is a situation where the man and/or info pages beat
the tar (hehehe) out of the usage strings (--help option for
some progs). Recommended reading for all unfamiliar w/
the Linux commandline, myself included ( I can get around
all right, but I am a far cry from a guru).

HTH,
Tarkin