Re: [mu INSTALL] how to extract ext.tgz

From: Renato (renato@jfrj.gov.br)
Date: Fri Feb 25 2000 - 14:08:35 CET


I suggest you install muLinux booting from floppies created acording instructions in the site.
When installing, if you answer YES to question about EXT, the install script will unpack EXT.tgz for you.
I suppose you should like to read the explanation below about archiving.
It is a clarifying message from Gerhard Thimm to Vieira Netto.

Renato

-----------------Begin----------------

Vieira Netto schrieb:
>
> Hello World of MuLinux!
>
> Help/archiving. It says that -z is illegal:
>
> /# cat iptraf.tgz | gzip -dc | tar -zxf
> tar: illegal option -- z
> Usage: tar -c[bfvw] device block filename..
> tar -r[bvw] device block [filename...]
> tar -t[vf] device
> tar -u[bvw] device block [filename...]
> tar -x[flmovw] device [filename...]
>

Most tar's I know do not support the z option, which activate a
compression or zip tool. I normally use pipelinig like this:
cat anarchive.tgz | gunzip | tar xf -

> I just followed the instructions except a minus sign at the end of line.
> What is it for???

The short answer, the minus sign is a place holder for pipe-archivs.

And a longer answer, I hope not to long :-)
This is one of that things, I very like in .*nix (sorry, grep notation:)
the standard i/o-channels (stdin and stdout in k&r|ansi-c-notation)

OK. You use the minus sign if the archive-data comes from stdin, like
the above "anarchiv.tgz-example and not from a file. If you write the
archive into a pipe the minus sign represents the stdout-channel, like
this:
tar cf - | gzip >anotherarchiv.tgz

One of my favorites command-pipelines is this:

cd fromdir; tar cf - . | (cd todir; tar xfvBp - )

which copies a whole fromdir-tree, much more reliable than
 cp -r fromdir todir. The first minus sign means stdout, the 2nd stdin.
The dot (.) after the first minus sign means the current dir. Without
the v-option the command works silent.

The problem with tar paramaters is, that the first parameter means the
archive, the folling ones the files and dirs to colllect or extract
to/from that "first-paramater-archiv". look at this:
tar cf - README *.c | gzip > arc.tgz
Whitout the minus sign it is difficult to realize the meaning of README.
Is it a file to-tar-it or is it the name of the archive.

(Because the shell handles the pipe-sign (|), the tar command as no
idea, that you would like to pipe the output)

-----------------End------------------------

*********** REPLY SEPARATOR ***********

On 25/02/00 at 09:41 Martin_Doering@mn.man.de wrote:

>Hi!
>
>How ist the ext.tgz extension package packed? I cannot unpack any of the
>extension packages with gzip. I would like to just get some files out of it.
>
>Martin
>
>
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