Provided by: zsync_0.6.1-3ubuntu1_amd64 bug

NAME

       zsyncmake - Build control file for zsync(1)

SYNTAX

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

       zsync -V

DESCRIPTION

       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.

OPTIONS

       -b blocksize
              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.

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

       -o outputfile
              Override the default output file name.

       -u url 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.

       -U url 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.

EXAMPLES

       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.

AUTHORS

       Colin Phipps <cph@moria.org.uk>

SEE ALSO

       zsync(1)