What the HECK is a "TAR-ball" ??!!
O.K., I'll bite - What is "tar"?
...GnuZIP?
Is "tar" available for OpenVMS?
How do I use VMS-TAR?
VMS TAR Caveats
Is GnuZIP available for OpenVMS?
How do I use GnuZIP?
GnuZIP Caveats
What are those file type extensions
again?
DJE Systems Links
"TAR-ball" is a UN*X term for a "tar" (Tape ARchiver) archive. The term frequently refers to a "tar" archive which has been compressed using the GnuZIP program (a "G-ZIPped tarball").
O.K., I'll bite - What is "tar"? ...GnuZIP?
"tar" is the UN*X equivalent to the OpenVMS BACKUP program. It stores entire directory trees in a more-or-less proprietary format. We say "more-or-less proprietary format" because while it does not conform to ANSI standards for labelled datasets on magnetic tape, the "tar" archive format is now specified as an "RFC" which has been accepted as an ANSI standard, which means it can be supported across a wide variety of environments. "tar" harks back to the earliest days of UN*X.
GnuZIP is an effort by the freeware community to develop a compression and decompression program which is freely available and redistributable without compromising or usurping existing copyrights and patents on compression methods. GnuZIP is normally found only in the UN*X world, and is not fully functional on OpenVMS (although it is usable to a limited degree).
Most UN*X-land software is distributed in "tarballs". The OpenVMS equivalent would be to build a BACKUP saveset with a /BLOCK size of 2048 and then pack it into a .ZIP archive or DCX/data-reduced text library. ZIP generally produces better compression than DCX, however.
Is "tar" available for OpenVMS?
Yes! You can find it here on our site as VMSTAR.ZIP, or on Hunter Goatley's FILESERV site.
VMS-TAR has a DCL-like command line interface, but also supports UN*X-like command syntax. To view the command-line options and qualifiers, invoke VMSTAR like so:
$ TAR:==$ddcu:[dir]VMSTAR
$ TAR/HELP
Example:
$ TAR/EXTRACT archive_name.TAR
Some versions of "tar" support the ability to decompress GnuZIPped "tar" archives ("tar-balls"). TAR for OpenVMS does not include this support as of this writing (1-Jan-1998).
Is GnuZIP available for OpenVMS?
Yes! You can find it here on our site as GZIP124.ZIP, on Hunter Goatley's FILESERV site, and on the InfoZip FTP site.
GnuZIP has only a UN*X-like command syntax. To view the command-line options, invoke GnuZIP like so:
$ GZIP:==$ddcu:[dir]GZIP
$ GZIP -H
The GnuZIP program (called GZIP for short) includes both the compress and decompress functionality.
For example:
$ GZIP -C archive_name.GZ filespec ! Create an
archive
$ GZIP -D archive_name.GZ ! Decompress an archive
The port of GnuZIP to OpenVMS is somewhat incomplete. Only the basic functions are supported.
GnuZIP for OpenVMS does not interface with RMS - all files are treated as "stream" files, RMS attributes are NOT preserved. Files restored from .GZ archives always have Stream-LF record attributes.
After restoring files from a .GZ archive, the archive file is deleted. There is no over-ride for this.
When listing the contents of a .GZ archive, GnuZIP for OpenVMS does not know the size of the contents of the archive; however, extracts do work successfully.
As with ZIP for OpenVMS V2.x and later, or UNZIP for OpenVMS V5.1 and later, when using command line options that must be uppercase, the entire options string must be enclosed in quotes. This is due to a "feature" of the C Runtime Libraries which is required for ANSI compliance, not because it's right.
What are those file type extensions again?
".tar" files are usually "tar" archives. Even though "tar" stands for "Tape ARchiver", you can have it write its output to a disk file. The name of such a file is usually given a ".tar" extension.
".gz" files are usually GnuZIP compressed archives. This differentiates them from ".zip" files which are output by the freeware ZIP program and ".z" files which are usually output by the UN*X "compress" utility.
".tgz" files are usually GnuZIPped "tar" archives. You might also see the name end with ".tar.gz". However, many non-UN*X operating systems are limited to a single period in the filespec., and some even limit the extension to three characters (such as DOS with its "8.3" limitation: eight (8) characters before the period, three (3) characters after).
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