On Sat, Apr 27, 2002 at 04:55:38PM -0500, Jackie LaVaque wrote:
> A friend gave me a CD with some very cool astronomical charting/graphing
> software on it, called "Xephem". I would like to install it on my Mac-based
> Yellow Dog Linux system, but unfortunately, friend gave me a one-line
> cryptic sentence as installation instructions ("untar in root) and I don't
> know what to do next. I have no experience installing software in Linux and
> friend is unavailable this weekend for installation instructions.

tar is the standard *nix Tape ARchiver.  It takes lots of small files
and turns them into one big file.  Modern tars also allow you to tell
them to pipe the data through a compression program so you can
archive and compress in a single step.

The tarfile that your friend gave you is probably named something
like either Xephem.tar, Xephem.tar.gz, or Xephem.tgz.  If it ends in
.tar, the command to dearchive it is

tar xvf Xephem.tar

If it ends in .tar.gz or .tgz, then it has also been compressed using
gzip and the command to decompress and dearchive is

tar xvzf Xephem.tgz

In both cases, the 'v' is optional; it stands for 'Verbose' and
causes tar to print the name of each file in the archive as it is
extracted.  I always use it, but nothing will break if you don't.

Other compression formats are possible, such as .Z for the original
unix 'compress' command's format or .bz2 (or .bzip2) for (surprise,
surprise) bzip2.  The relevant switches can be found by reading `man
tar`.  gzip is the most common, though, so that's the only one I've
mentioned above.

Finally, if you have the disk space, I would recommend first
untarring the file in a scratch directory so you can take a look at
what it's going to install and verify that it won't disrupt your
system too badly.  Depending on how adventurous you feel, you can
then either untar it again in the root directory or manually move
files from the scratch directory to permanent homes in more stable
sections of the filesystem.

-- 
When we reduce our own liberties to stop terrorism, the terrorists
have already won. - reverius

Innocence is no protection when governments go bad. - Tom Swiss