zsyncmake - Build control file for zsync(1)

       Colin Phipps <cph@moria.org.uk>

       Constructs a metafile for the zsync client program to use to perform partial file downloads. filename  is
       the  file  that  users  wish  to  downloads;  zsyncmake  constructs  the  appropriate metafile and writes
       filename.zsync in the current directory.

       zsync will need at least one URL from which to download the file content. If the .zsync will  be  in  the
       same directory as the file to download, you can accept the default - zsync includes a relative URL in the
       control  file.  If  not,  use  the  -u  option  to specify the URL. You should also specify a URL for the
       uncompressed content with -U if available, as zsync can make use of this  for  more  efficient  downloads
       sometimes.  (You can edit the .zsync file and add these afterwards - it has a simple key: value format in
       the header - but I suggest you only do this once you are familiar with the tool.)

       Note that zsyncmake itself does not (currently) verify the URLs or download any data,  you  must  provide
       the file data locally and check the URLs yourself.

       zsyncmake -C -u http://ftp.uk.debian.org/debian/dists/sarge/main/binary-i386/Packages.gz Packages.gz

       Note use of -C to save the client compressing the file on receipt; the Debian  package  system  uses  the
       file uncompressed.

       zsyncmake -z my-subversion-dump

       In  this case there is a large, compressible file to transfer. This creates a gzipped version of the file
       (optimised for zsync), and a .zsync file. A URL is automatically added assuming that the two  files  will
       be served from the same directory on the web server.

       zsyncmake                                              -e                                              -u
       http://www.mirrorservice.org/sites/ftp.freebsd.org/pub/FreeBSD/ports/distfiles/zsync-0.2.2.tar.gz
       zsync-0.2.2.tar.gz

       This creates a zsync referring to the named source tarball, which the client  should  download  from  the
       given  URL. This example is for downloading a source tarball for a FreeBSD port, hence -e is specified so
       the client will be able to match its md5sum.

       zsyncmake - Build control file for zsync(1)

-bblocksize
              Specify the blocksize to the underlying rsync algorithm. A smaller blocksize may be more efficient
              for  files  where  there  are  likely  to be lots of small, scattered changes between downloads; a
              larger blocksize is more efficient for files with fewer or less scattered changes. This  blocksize
              must  be  a power of two. If not specified, zsyncmake chooses one which it thinks is best for this
              file (currently either 2048 or 4096 depending on file size) - so normally tyou should not need  to
              override the default.

       -C     Tells  zsyncmake not to generate any instructions in the .zsync telling the client to compress the
              data it receives. This is implied by -z, but this option is here  in  case  you  compress  a  file
              yourself only for the transfer, but want the client to end up with the uncompressed file (e.g. you
              are  transferring  an ISO, which is held compressed on the server, but which the client cannot use
              unless it is uncompressed). Without -C, zsyncmake  will  produce  directions  for  the  client  to
              compress  the file it receives where appropriate; -C is here so you can stop it telling the client
              to do that.

       -e     Tells zsyncmake that the client must be able to receive the exact file that was supplied.  Without
              this  option,  zsyncmake  only gives a weaker guarantee - that the client will receive the data it
              contains (e.g. it might transfer the uncompressed version of a .gz to the client). Note that  this
              still  doesn't  guarantee  that the client will get it - the client could ignore the directives in
              the zsync file, or might be incapable of exactly reproducing the compression used. But with -e you
              know that zsyncmake has made it possible to get the exact data - it will exit with an error if  it
              cannot.

       -ffilename
              Set  the  filename to include in the output file (this is what the file will be called when a user
              finished downloading it).

       -ooutputfile
              Override the default output file name.

       -uurl Specifies the URL from which users can download the content of the supplied file. Users  need  the
              control file in order to find out what parts of the file they already have, and they need the URLs
              to  retrieve  the parts of the file that they don't already have. You can specify multiple URLs by
              specifying -u multiple times. If not specified, zsync assumes that the file and  the  .zsync  will
              reside in the same public directory, and includes a single relative URL.

       -Uurl Specifies  a URL corresponding to the decompressed content of the file (only applicable if it is a
              gzip file). zsync can sometimes download more efficiently from the uncompressed data than from the
              compressed data - it will take advantage of this if available. If no  URLs  are  specifies,  zsync
              looks for a file without the .gz extension and assumes that this will be in the same public dir as
              the .zsync, and includes a relative URL to it.

       -v     Enable verbose messages.

       -V     Prints the version of zsync.

       -z     Compress  the  file  to  transfer.  Note  that this overwrites any file called filename.gz without
              warning (if you don't give a filename, e.g. because you are reading from stdin,  then  zsync  will
              use the name supplied with -f, or as a last fallback, zsync-target.gz).

       zsync can work with compressed data, and, in most cases where the data is not already compressed, it is
       more efficient to compress it first. While you can just compress the file to transfer with gzip, if you
       use this option then zsyncmake will compress the file for you, producing a .gz file which is optimised
       for zsync. This can be 30% more efficient at download time than compressing with gzip --best - but the
       compressed file will not be as small at that produced by gzip.

       -Z     zsyncmake   automatically   looks  inside  gzip  compressed  files  and  exports  the  underlying,
              uncompressed data to the zsyncmake file. In testing this has proved to  provide  greater  download
              efficiency. -Z overrides the default behaviour and treats gzip files as just binary data. Use this
              if  it  is  essential  that  the  user  receives  the  compressed  data  (for  instance  because a
              cryptographic signature is available only for the compressed data). zsync is typically no  use  if
              you  specify  -Z,  unless  the gzip file was compressed with the special --rsync option to make it
              friendly to differential transfers.

zsync(1)

Colin Phipps                                          0.6.2                                         zsyncmake(1)

       zsyncmake  [  {  -z  |  -Z  }  ] [ -e ] [ -C ] [ -u url ] [ -U url ] [ -b blocksize ] [ -o outfile ] [ -f
       targetfilename ] [ -v ] filename

       zsync -V