[comp.unix.questions] un-tarring a disk file

ae219dp@prism.gatech.EDU (Devon Prichard) (05/03/90)

summary says it all; I have a file (gnuplot.tar.Z from Duke Univ.)
which I want to bust out on a unix system.  I looked at the man
pages for tar, but it sort of implied it wanted a disk-to-tape
or tape-to-disk operation.  how do I untar a disk file and write
disk files??

thanx in advance

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 | Devon Prichard             making the world safe for helicopters ... |
 | ae219dp@prism.gatech.edu                                             |
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gwyn@smoke.BRL.MIL (Doug Gwyn) (05/03/90)

In article <8832@hydra.gatech.EDU> ae219dp@prism.gatech.EDU (Devon Prichard) writes:
>summary says it all; I have a file (gnuplot.tar.Z from Duke Univ.)
>which I want to bust out on a unix system.  I looked at the man
>pages for tar, but it sort of implied it wanted a disk-to-tape
>or tape-to-disk operation.  how do I untar a disk file and write
>disk files??

The "f" option to "tar" allows you to specify an archive file name
in place of the default (that is normally a magtape device file name).
However, for a .Z file you should first "uncompress" it.

jik@athena.mit.edu (Jonathan I. Kamens) (05/04/90)

In article <12772@smoke.BRL.MIL>, gwyn@smoke.BRL.MIL (Doug Gwyn) writes:
|> The "f" option to "tar" allows you to specify an archive file name
|> in place of the default (that is normally a magtape device file name).
|> However, for a .Z file you should first "uncompress" it.

  Actually, if you have "compress" and "uncompress" at your site, you
probably have "zcat" as well.  At the very least, you should have some
way of uncompressing a file to the standard output, rather than
uncompressing it back into disk space.

  If you do, then it's better to do the uncompress and untar at the same
time, so you don't have the uncompressed tar archive taking up extra
space (that is, after all, why it's compressed :-).  When I get a
compressed tar archive, I usually use:

  zcat filename.tar.Z | tar xvf -

The "-" for the filename tells tar to read from the standard input, as
per the tar man page.

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