tar does not 'tar' / 'untar' tarballs anymore

embeddedPROJECTS · 09-10-2014, 07:50 PM

When i try to extract my tar.gz archives with tar xvzf i get:

tar: muxPi_Arch_13.img: Wrote only 2559 of 10240 bytes

Tested gzip and it works, tryed to compress and extract with zip and 7zip
the same files and they worked, reinstalled tar and updated, problem remains.

Some people had a lack of space in the HDD but if i do a check is not what the problem
seems to be:

bash-4.2# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 413G 84G 309G 22% /
tmpfs 1.5G 524K 1.5G 1% /dev/shm
/dev/sdb1 459G 89G 347G 21% /mnt/HDD2

Any idea? Thanks.

Didier Spaier · 09-10-2014, 09:34 PM

It's hard to help if we don't know the characteristics of the file. Please provide output of following command:

Code:

file <tarball>

Also, if possible indicate the way the tarball was built, its content, and if publicly available a link to it. Bear also in mind that the tar command is generally not relevant for compressed single files.

In addition for recent versions of tar, the z option (as the j option) is generally useless as tar can "guess" the compression algorithm.

ruario · 09-11-2014, 12:44 AM

I'm gonna bet that is not a tar file. Try bsdtar which is also installed. It can read a variety of formats. You can check the format by issuing the following

Code:

bsdtar tvvf muxPi_Arch_13.img

ruario · 09-11-2014, 07:21 AM

Quote:

Originally Posted by Didier Spaier

In addition for recent versions of tar, the z option (as the j option) is generally useless as tar can "guess" the compression algorithm.

Generally but not totally. If the compressed tar file is received through a pipe you must specify the correct decompressor, e.g.

Code:

$ cat example.tar.gz | tar x
tar: Archive is compressed. Use -z option
tar: Error is not recoverable: exiting now
$ cat example.tar.bz2 | tar x
tar: Archive is compressed. Use -j option
tar: Error is not recoverable: exiting now
$ cat example.tar.xz | tar x
tar: Archive is compressed. Use -J option
tar: Error is not recoverable: exiting now
$ cat example.tar.lz | tar x
tar: Archive is compressed. Use --lzip option
tar: Error is not recoverable: exiting now

As a side note, tar clearly knows which compressor is being used, so why not just use it rather than telling the user to specify it? Interestingly the other major tar variant (bsdtar) will just handle automatic decompression without an option, even when a pipe is used.

GazL · 09-11-2014, 08:02 AM

Quote:

Originally Posted by ruario

As a side note, tar clearly knows which compressor is being used, so why not just use it rather than telling the user to specify it?

I think I prefer the "Hmmm, it looks like a _____ but I'd rather you confirm it" approach, even if it means more work on the part of the user.

Of course, UNIX purists would argue that tar shouldn't be doing any compression/decompression itself anyway!

ruario · 09-11-2014, 08:59 AM

Quote:

Originally Posted by GazL

I think I prefer the "Hmmm, it looks like a _____ but I'd rather you confirm it" approach, even if it means more work on the part of the user.

Fair enough but then why do they do automatic decompression when a pipe is not used. Either do it all the time or not at all. GNU tar's way of being automatic half the time is just weird IMHO.

Quote:

Originally Posted by GazL

Of course, UNIX purists would argue that tar shouldn't be doing any compression/decompression itself anyway!

Yep.

embeddedPROJECTS · 09-11-2014, 06:32 PM

Quote:

Originally Posted by Didier Spaier

It's hard to help if we don't know the characteristics of the file. Please provide output of following command:

Code:

file <tarball>

Also, if possible indicate the way the tarball was built, its content, and if publicly available a link to it. Bear also in mind that the tar command is generally not relevant for compressed single files.

In addition for recent versions of tar, the z option (as the j option) is generally useless as tar can "guess" the compression algorithm.

It's a Raspberry .img i took with command dd, anyway files are good, on the other Slackware machine (same version) it works.

Here what you asked for:

file muxPi-14-Arch.tar.gz
muxPi-14-Arch.tar.gz: gzip compressed data, from Unix, last modified: Thu Mar 20 23:15:32 2014

astrogeek · 09-11-2014, 07:55 PM

Quote:

Originally Posted by embeddedPROJECTS

When i try to extract my tar.gz archives with tar xvzf i get:

tar: muxPi_Arch_13.img: Wrote only 2559 of 10240 bytes

Tested gzip and it works, tryed to compress and extract with zip and 7zip
the same files and they worked, reinstalled tar and updated, problem remains.

I have read this several times but am not sure I understand just what you mean.

Does gzip successfully open that file, but tar will not? That would mean that it was created with gzip, but not tar.

Your file output would look the same in either case I think.

So, in other words, if it opens with gzip but not tar, then use gzip, the file is misnamed as tar.gz and should be just gz. Hope that made sense.

You also said that you created it with dd. Was that dd | gzip? Can you tell us the exact command used to create it?