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1991-06-08
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E x T A R 1.0
==============
February 1990
Free Software by TapirSoft Gisbert W.Selke
On Unix machines, probably the most common way of bundling a set of
files (for purposes of mailing or whatever) is to put them into a TAR
file, i.e., a Tape ARchive, conventionally recognizable by a name
ending in .tar. (These TAR files are then usually compressed,
recognizable by a file name ending in .tar.Z. But this is an entirely
different story that we won't discuss here.)
Occasionally, one gets a TAR on an MS-DOS machine and would like to
extract some, or all, of its members; and in fact, there are a number of
programmes around that list TAR contents, extract from them and even
build new ones. So far, so good; but they -- at least the ones I have
encountered so far -- don't cater for file names which are perfectly
valid under Unix but are illegal under MS-DOS. E.g., file names could
contain multiple periods, start with a period, or contain all sorts of
nasty characters that are interpreted as delimiters by DOS or are
not permitted for some reason or other. Trying to extract those files
will just fail. Also, Unix file names are case-sensitive -- hence, a TAR
might contain read.me and READ.ME (and possibly Read.Me). For DOS, these
all look the same; hence, extracting one of them will overwrite the
others that have the 'same' name.
Hence I wrote ExTAR, which is a very crude, no-frills utility with one
purpose only: extract all members of a TAR, creating directories as
necessary, and renaming files to make them acceptable to DOS; all the
time taking care not to overwrite any existing files. It does so by
truncating names and converting offending ones to nice ones. Exactly
what it does is shown on the screen; if you need to save this
information, you'd better write them down while they zip by, or maybe
redirect all these messages to some log file.
Usage is simple:
extar filename
is all there is to it. (You may omit the extension .TAR, which is
added automatically iff the filename contains no period.) Files are
written to the current directory; subdirectories are created as
necessary. If a file of the 'same' name already exists, the user is
asked if overwriting is OK; if not, the name is mangled some more to
make it unique.
ExTAR does not do any of the fine things the other TAR processors do; in
particular, it does no listing of contents and no error checking. Also,
since I don't have any official documentation of the TAR format, I may
have overlooked certain special features embedded into some... I don't
know, and frankly, I don't care too much. So let's leave it this way:
this is free software, supplied as-is, no guarantees for anything.
Source (TurboPascal 5.5+) is provided; if it doesn't suit your needs,
feel free to hack it. Just give credit where credit is due, and don't
you sell my product; rather, if you think others might like your stuff,
give it to them like I do. (Hey, even I might be interested!) -- If, on
the other hand, you have a plain simple TAR containing a file name that
ExTAR chokes on, I just might be interested in fixing it myself.
Describe it to me, or better yet, send me a copy of the TAR.
Enjoy.
TapirSoft
Gisbert W.Selke <s00100@dbnrhrz1.bitnet>
Ermekeilstrasse 28
D-5300 Bonn 1
Germany