Hi again, Just as a side note, this was apparently already added to info-zip in version 3.0 (flag -FI).
Regards, Alex On 1/8/10, Alexander T <[email protected]> wrote: > Hi Tim, > > Thank you for the information. I have submitted the same feature > request to info-zip to see if they could implement it. Considering > that the problem with the header appearing first would mostly apply to > sequential output, would it be possible to add support for this when > tar is writing the output file itself? Or maybe there is some other > chunking option which would limit the buffer size? > > Regards, > > Alex > > On 1/7/10, Tim Kientzle <[email protected]> wrote: >> The tar format has to know the size of the entry >> before it can write the header that goes before >> the data. >> >> With your proposal, there's no way for tar to >> know the size of the data without actually >> reading all of the data. To work around this, >> tar would have to copy the data to a temporary >> file itself. So you wouldn't really gain >> anything over using a temporary file. >> >> In some cases, you might have a programmatic >> way to determine the size in advance. If this >> is true for your application, you might consider >> writing a custom archiving program based on >> the libarchive library, which was designed to >> make it very easy to create tar archives with >> dynamically-generated content. (If you cannot >> determine the size in advance, libarchive now >> has support for writing zip format, which does >> not require knowing the size in advance.) >> >> http://libarchive.googlecode.com/ has full >> details, including example code. >> >> Cheers, >> >> Tim Kientzle >> >> Alexander T wrote: >>> Hi, >>> >>> This is my first message to this list, so hi everyone and I hope that >>> this is the right place to post. I would like to submit a feature >>> request: to add a flag for including the contents of FIFO:s, like >>> --dereference, but for named pipes. >>> >>> The problem this would solve is tar:ing multiple large program outputs >>> without using intermediate files, something like >>> >>> mkdir bck >>> mkfifo bck/1.dump >>> mkfifo bck/2.dump >>> dbdump db1 > bck/1.dump & >>> dbdump db2 > bck/2.dump & >>> tar -c?f bck.tar bck >>> >>> It is currently of course possible to come up with some workarounds, >>> but they have drawbacks and this would IMHO be a very nice addition. >>> >>> There are some google results with people having the same problems: >>> http://www.unix.com/unix-advanced-expert-users/30365-tar-fifos.html >>> , >>> http://stackoverflow.com/questions/2021873/linux-adding-named-files-to-a-zip-archive-from-a-pipe/2022012#2022012 >>> and >>> http://www.linuxquestions.org/questions/programming-9/make-tarziprar-play-nice-with-named-pipes-593392/ >>> >>> >>> Best Regards, >>> >>> Alexander T >>> >>> >>> >>> >> >
