tar and lzma

Charles Wilson cygwin@cwilson.fastmail.fm
Sun May 4 16:40:00 GMT 2008


Yaakov (Cygwin Ports) wrote:
> Eric Blake wrote:
> | automake's dist-lzma already functions if you install lzma (I know,
> | because I used it when creating m4 1.4.10b); automake uses 'tar | lzma'
> | rather than 'tar --lzma'.
> 
> Furthermore, 'make distcheck' uses 'unlzma | tar'.  Our lzma-4.43-2 does
> not provide unlzma.

That's because our lzma is derived from the LZMA SDK, the original, 
derived-from-7zip-windows-oriented code, by Igor Pavlov.

The near-standard on unix is 'lzma-utils' which is separately developed 
(but originally derived from and developed in cooperation with Igor). 
This one provides all those goodies like
usr/bin/lzcat
usr/bin/lzcmp
usr/bin/lzdiff
usr/bin/lzegrep
usr/bin/lzfgrep
usr/bin/lzgrep
usr/bin/lzless
usr/bin/lzmore
usr/bin/unlzma


To make matters more confusing, the debianized patches that *our* 
version of the lzma program uses, actually originated from the 
lzma-utils project, giving the lzma.exe application a more gzip-like 
command like interface.  But those patches did not bring over the 
additional stuff -- like unlzma -- from lzma-util.

I'd *almost* go so far as to suggest that the cygwin lzma package be 
modified to use the lzma-util source, like most of the other unix 
distros do.  However, the basic core routines from lzma-util in the most 
recent stable release are still based on LZMA SDK 4.43, rather than the 
current LZMA SDK 4.57.  And the development versions of lzma-util are 
explicitly alpha and *not ready for archival use*.

--
Chuck



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