Hi James, Tks for your advice. I made following test; 1) re-created another compressed tarball on the old directory, old-AAA $ tar -jcpf AAA.tar.bz2 old-dirA/ 2) used following command line to create a new compressed tarball $ bunzip2 AAA.tar.bz2 ; tar -upf AAA.tar /home/path/to/new-dirA ; bzip2 AAA.tar The new compressed tarball created consisted of the old and new directories, without removing the old directory. I think tar and bzip2 are not the tools for my application. Any other suggestions? TIA B.R. SL > Stephen Liu wrote: > > I create a tarred file then compressed with bzip with following > command > > line; > > > > # tar -jcpf AAA.bz2 /home/path/to/dirA > > > > dirA is about 2G in size. > > > > After working several days on dirA I want to create a new > compressed > > tarred file. Instead of repeating the above command, is there a way > > starting from the old file AAA.bz2 making use of the options -u, > -N, > > -G, etc. to reduce the compressing time? I looked around on man tar > and > > Internet and could not sort out their combination on the command > line. > > You wouldn't be able to do this with command lines. bzip2 compresses > 900K [1] blocks at a time: it might be possible, if a 900K block > hasn't > changed, to "carry it forward" from the earlier .tar.bz2 to the next, > but you'd need to write a program that got pretty deep into the .tar > and > .bz2 format. [2] > > If you really want faster compression, possibly at the expense of > file-size, then gzip might be a much better answer for you. It > doesn't > compress as well, but it can compress a lot faster. (Quite how much > faster depends on your processor architecture). > > Hope this helps, > > James. > > [1] By default: see man bzip2 for details. > [2] Someone's going to quibble if I don't quote the bzip2 man page > saying > bzip2 compresses files in blocks, usually 900kbytes long. > Each block > is handled independently. If a media or transmission error > causes a > multi-block .bz2 file to become damaged, it may be possible to > recover > data from the undamaged blocks in the file. > -- > E-mail address: james | Whenever [Richard I] returned to England he > always > @westexe.demon.co.uk | set out again immediately for the > Mediterranean and > | was therefore known as Richard Gare de Lyon. > | -- '1066 and All That' > > -- > fedora-list mailing list > fedora-list@xxxxxxxxxx > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list >
