compressed file question

compressed file question

Post by Quint Van Dema » Sat, 06 Feb 1999 04:00:00



How exactly does one extract the files from a .tar.gz archive

using gunzip I got it down to just a .tar file

if I then run 'tar' my machine just hangs out until I hit Ctrl-C

where am I going wrong?

Thanks

Quint

 
 
 

compressed file question

Post by Patrik Magnuss » Sun, 07 Feb 1999 04:00:00




|> How exactly does one extract the files from a .tar.gz archive
|>
|> using gunzip I got it down to just a .tar file
|>
|> if I then run 'tar' my machine just hangs out until I hit Ctrl-C
|>
|> where am I going wrong?
|>
|> Thanks
|>
|> Quint
|>
|>
You can unpack it in a single step using tar -zxpvf file.tar.gz
All those options are probably an overkill, but I've never
managed to learn what each one does.

/Patrik

 
 
 

compressed file question

Post by Seppo Pietikaine » Sat, 13 Feb 1999 04:00:00



> How exactly does one extract the files from a .tar.gz archive

> using gunzip I got it down to just a .tar file

> if I then run 'tar' my machine just hangs out until I hit Ctrl-C

> where am I going wrong?

> Thanks

> Quint

Hello Quint,

Assuming you've got a file like "xxx.tar.gz", you might want to

1. Uncompress the file (gz -extension implies 'gzip' compression):
   (I won't go into capability details of tar itself, see "man tar").

   $ gunzip xxx.tar.gz

        If you get weird and not so wonderful error messages it means
        that the file in question _was not_ a gzip compressed file, no
        reason, really, to try to go any further, try to download a new
        copy of the file, or complain to the originator of the file.

        (see "man gunzip" and "man gzip" )

   After successful 'gunzip' you'll have:
   $ ls xxx.tar
   xxx.tar

2. Check the contents of the 'TapeARchive -file':
   $ tar -vtf xxx.tar
        - or just -
   $ tar vtf xxx.tar

        (see "man tar" for details)
        (If you get strange error messages it means that the file
         _is not_ a tar -file, do as in #1)

3. Extract the contents of the tar-file (assuming you're happy with
   the destination directory paths in the archive):

   $ tar -xvf xxx.tar
    (The "v" -option is nice, since it will tell you what is happening
     while unarchiving the stuff)

   After a while, (depending on the size of the archive, or the size of
the
   individual components in the same), you will have the tar-file  
   extracted (maybe you hit the CTL-C too early?)

...

If your 'tar -command' just stays there (I don't think it'll hang your
machine though) it implies that it is expecting something from
the standard input. (Again, check "man tar" in your system, it's
perfectly legal, and actually _a very good thing_ for "tar" to
accept input from "stdin"!).

Hopefully you've had responses to clear your pbm. Your description
really wasn't terribly informative (what args did you specify with
the "tar" -cmd.?).

Best regards,
Seppo Pietikainen

 
 
 

1. To compress or not to compress, that is the question.

I sat here for quite a while and read all the responses which were
mostly off topic :)

Tape drives have a fixed transfer rate to the tape.  Say 5mb/sec.
If you are getting 2:1 compression, every 5mb to tape is 10mb of
your data.

Data is streaming through the controller at 10mb/sec and compressed
data is going onto the tape at it's steady old rate of 5mb/sec.

So, your backup runs twice as fast with 2:1 compression, subject to
other limiting factors like file reads and controller and bus
performance.

With a pci bus and decent controller they are not the bottleneck.
It will be a combination of read speed and compression ratios.

- Binary data (executables and the like) seem to compress about 2:1.
- Database and text data often compress much more.
- Compressed data doesn't compress further (.Z, .gz, many graphic
  formats).
- YMMV

I've never noticed uncompressable data to a tape drive in compressing
mode to run any slower than in non-compressing mode.

So, there is no reason beyond compatability ( with older non-compressing
or proprietary compression schemes ( which are no longer used as far
as I know)) to use non-compressing mode.  IMHO.
--
Do two rights make | Kevin Smith, ShadeTree Software, Philadelphia, PA, USA
a libertarian      | 001-215-487-3811  shady.com,kevin   bbs.cpcn.com,sysop
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