edoc wrote:
> TAR is an archiving methodology that contains its own unique archiving
> utility?
Tar is an age-old (think '70s) archiving utility. TAR = Tape
ARchiver. Using UNIX's built-in redirection/piping capabilities,
and various options in more recent versions, you can redirect its
output to a file. Numerous program support its format, although
there are several versions and not all implementations support all
its features.
For instance, Tar has some most excellent corruption recovery
routines. So if you have a corruption in the middle of your file,
it can usually recover most of the files after that point. Now
WinZip's Tar compatibility does *NOT* support nost of these
routines. In fact, besides not implementing them, it doesn't even
both to tell you there was a corruption! This leads many Windows
users to label Tar as a poor archiver which is simply not true.
Okay, now I'm getting on a tangent. ;-PPP
> RPM is an archiving methodology that uses CPIO as its archiving utility?
No, RPM is a packaging methodology. Outside of the Windows world
(and even increasingly in the Windows world, thanx to people like
ActiveState ;-), you _never_ install software via executable. It is
dangerous and a prime target for trojan horses. Executables
_should_ be packaged in a format that is not just a simple archive
of the files, but has all kinds of OS/version-specific information,
dependency/version checking (so you don't have conflicts, etc...),
checksum/tampering detection (e.g., MD5) and other details. The
only executable file used in installation is the controlled
packaging software itself.
CPIO (copy I/O) is just another archiver. RPM uses CPIO as its
archiving format. In fact, as you'll find with a lot of legacy UNIX
utilities, many are used for things never designed, but quite useful
thanx to UNIX's flexible file handling routines.
[ Side Note: TheBS's UNIX Rule #1 (which you'll learn, there are
three ;-): _Everything_ in UNIX is a file! ].
Even ISO9660, the file format of CD-ROMs, can also be considered an
archive format. Using mkisofs, you can make archives as well -- and
then burn them to CD. In fact, I'm writing a program called "car"
that is a CD-ROM ARchiver with Tar-like syntax.
[ Side Note: This "project" originally started out as a backup
script called "back2cd" that I wrote for Steve Litt. It should
allow you to backup between 1-2GB of data to a CD-ROM in a way you
can directly access when you want to restore a file. You simply use
the script, and then use your normal burning software to burn the
resulting ISO image (be it cdrecord on UNIX or CD Creator or Nero's
package on Windows). You can find here:
http://smithconcepts.com/files/scripts/back2cd.tcsh ]
Okay, now I'm really getting on tangents.
I guess the best way to explain this is by explaining it with
Windows terms. E.g., PKWare's Zip is both an archiver and
compression format using PKZip as the program. Newer InstallShield
versions can output an .inst (I believe that's the extension?)
"package" that is basically an self-installing .exe without the
executable part.
-- TheBS
-- Bryan "TheBS" Smith mailto:b.j.smith@ieee.org chat:thebs413 Engineer AbsoluteValue Systems, Inc. http://www.linux-wlan.org President SmithConcepts, Inc. http://www.SmithConcepts.com
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