tar extracts gzip file even without -z flag

ajayyadavmca · 03-26-2013, 08:15 AM

Hi, i was creating tar archive with tar command and extracting it.

To create tar: tar -cvzf test.tar.gz /test
To extract: tar -xvf test.tar.gz

extract command was a mistake, i should have used -z option for gzip filter. but interestingly it works even without -z. i couldn't found any useful reference on Google why it works.

I have CentOS 6.2 linux.

Can you please help me understanding why tar extract work for gzip archive without using -z flag? Is it expected?

yowi · 03-26-2013, 08:29 AM

I guess the -a (--auto-compress use archive suffix to determine the compression program) option is a default, or maybe your site has TAR_OPTIONS set.

sycamorex · 03-26-2013, 08:57 AM

Perhaps, this one:

Quote:

Compressed archives are recognised automatically, it is no longer necessary to specify -Z, -z, or -j options to read them. Thus, you can now run tar tf archive.tar.gz and expect it to work!

Source: http://www.gnu.org/software/tar/

gnashley · 03-26-2013, 11:33 AM

The '-a' option is in since tar-0.15, IIRC.