On 2011-01-07, Lin Sun wrote: > Do you know if this sentence is still valid -
> The tar package does not support the full POSIX tar standard nor more > modern GNU extension of said standard Absoluetly, yes. > since you think compress project should support up to 8GB? I am > hoping it is no longer valid. I don't really understand what it > means. :-( Unfortunately there is not one *tar* format. The initial format used (ustar) before it was ever standardized by POSIX is fully(?) supported. This format lacks quite a few important features like support for file names longer than 100 characters, larger files and more - so dialects emerged. The most popular variants stemmed from GNU tar and PAX. Each of the dialects used the extension mechanism built into to the original format but did so in different ways. Commons Compress tar code detects some of the extensions when reading archives and can write archives using the GNU extension for longer file names. It does not support the full range of extensions, neither when reading nor writing. POSIX standardization came after the dialects emerged. It addressed some of the original shortcommings, in part by using yet a different set of extensions. More recent versions of GNU tar (those less than four years old or so) support the POSIX standard and will use it when creating new archives. The "longfile" format used by Commons Compress is called "oldgnu" by GNU tar and deprecated there. > Also, is true streaming supported? I'm not sure I understand the question. Tar archives consist of blocks so sometimes it will be necessary to read more data than your read requires (to read a full block) or writes will be delayed until a block is full (or the archive is closed). In general it should be possible to read/write archives in a streaming manner, though. Stefan --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
