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DOS: Update the docs and include notes about 8.3 filenames.

This commit is contained in:
Lasse Collin 2011-04-10 14:58:10 +03:00
parent ebd54dbd6e
commit 9e807fe3fe
2 changed files with 125 additions and 11 deletions

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XZ Utils on DOS
===============
Building XZ Utils for DOS
=========================
Introduction
@ -77,12 +77,3 @@ Building
are not built. Having e.g. xzdec.exe doesn't save much space compared
to xz.exe, because the DJGPP runtime makes the .exe quite big anyway.
Bugs
xz doesn't necessarily work in Dosbox. It should work in DOSEMU.
Pressing Ctrl-c or Ctrl-Break won't remove the incomplete target file
when running under Windows XP Command Prompt (something goes wrong
with SIGINT handling). It works correctly under Windows 95/98/98SE/ME.

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dos/README.txt Normal file
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XZ Utils on DOS
===============
DOS-specific filename handling
xz detects at runtime if long filename (LFN) support is
available and will use it by default. It can be disabled by
setting an environment variable:
set lfn=n
When xz is in LFN mode, it behaves pretty much the same as it
does on other operating systems. Examples:
xz foo.tar -> foo.tar.xz
xz -d foo.tar.xz -> foo.tar
xz -F lzma foo.tar -> foo.tar.lzma
xz -d foo.tar.lzma -> foo.tar
When LFN support isn't available or it is disabled with LFN=n
environment setting, xz works in short filename (SFN) mode. This
affects filename suffix handling when compressing.
When compressing to the .xz format in SFN mode:
- Files without an extension get .xz just like on LFN systems.
- *.tar files become *.txz (shorthand for *.tar.xz). *.txz
is recognized by xz on all supported operating systems.
(Try to avoid confusing this with gzipped .txt files.)
- Files with 1-3 character extension have their extension modified
so that the last character is a dash ("-"). If the extension
is already three characters, the last character is lost. The
resulting *.?- or *.??- filename is recognized in LFN mode, but
it isn't recognized by xz on other operating systems.
Examples:
xz foo -> foo.xz | xz -d foo.xz -> foo
xz foo.tar -> foo.txz | xz -d foo.txz -> foo.tar
xz foo.c -> foo.c- | xz -d foo.c- -> foo.c
xz read.me -> read.me- | xz -d read.me- -> read.me
xz foo.txt -> foo.tx- | xz -d foo.tx- -> foo.tx !
Note that in the last example above, the third character of the
filename extension is lost.
When compressing to the legacy .lzma format in SFN mode:
- *.tar files become *.tlz (shorthand for *.tar.lzma). *.tlz
is recognized by xz on all supported operating systems.
- Other files become *.lzm. The original filename extension
is lost. *.lzm is recognized also in LFN mode, but it is not
recognized by xz on other operating systems.
Examples:
xz -F lzma foo -> foo.lzm | xz -d foo.lzm -> foo
xz -F lzma foo.tar -> foo.tlz | xz -d foo.tlz -> foo.tar
xz -F lzma foo.c -> foo.lzm | xz -d foo.lzm -> foo !
xz -F lzma read.me -> read.lzm | xz -d read.lzm -> read !
xz -F lzma foo.txt -> foo.lzm | xz -d foo.lzm -> foo !
When compressing with a custom suffix (-S .SUF, --suffix=.SUF) to
any file format:
- If the suffix begins with a dot, the filename extension is
replaced with the new suffix. The original extension is lost.
- If the suffix doesn't begin with a dot and the filename has no
extension and the filename given on the command line doesn't
have a dot at the end, the custom suffix is appended just like
on LFN systems.
- If the suffix doesn't begin with a dot and the filename has
an extension (or an extension-less filename is given with a dot
at the end), the last 1-3 characters of the filename extension
may get overwritten to fit the given custom suffix.
Examples:
xz -S x foo -> foox | xz -dS x foox -> foo
xz -S x foo. -> foo.x | xz -dS x foo.x -> foo
xz -S .x foo -> foo.x | xz -dS .x foo.x -> foo
xz -S .x foo. -> foo.x | xz -dS .x foo.x -> foo
xz -S x.y foo -> foox.y | xz -dS x.y foox.y -> foo
xz -S .a foo.c -> foo.a | xz -dS .a foo.a -> foo !
xz -S a foo.c -> foo.ca | xz -dS a foo.ca -> foo.c
xz -S ab foo.c -> foo.cab | xz -dS ab foo.cab -> foo.c
xz -S ab read.me -> read.mab | xz -dS ab read.mab -> read.m !
xz -S ab foo.txt -> foo.tab | xz -dS ab foo.tab -> foo.t !
xz -S abc foo.txt -> foo.abc | xz -dS abc foo.abc -> foo !
When decompressing, the suffix handling in SFN mode is the same as
in LFN mode. The DOS-specific filenames *.lzm, *.?-, and *.??- are
recognized also in LFN mode.
xz handles certain uncommon situations safely:
- If the generated output filename refers to the same file as
the input file, xz detects this and refuses to compress or
decompress the input file even if --force is used. This can
happen when giving an overlong filename in SFN mode. E.g.
"xz -S x foo.texinfo" would try to write to foo.tex which on
SFN system is the same file as foo.texinfo.
- If the generated output filename is a special file like "con"
or "prn", xz detects this and refuses to compress or decompress
the input file even if --force is used.
Bugs
xz doesn't necessarily work in Dosbox. It should work in DOSEMU.
Pressing Ctrl-c or Ctrl-Break won't remove the incomplete target file
when running under Windows XP Command Prompt (something goes wrong
with SIGINT handling). It works correctly under Windows 95/98/98SE/ME.