zsync(1)							   File Transfer							  zsync(1)

NAME

       zsync - Partial/differential file download client over HTTP

SYNTAX

       zsync [ -u url ] [ -i inputfile ] [ -o outputfile ] [ { -s | -q } ] [ -k file.zsync ] [ -A hostname=username:password ] { filename | url }

       zsync -V

DESCRIPTION

       Downloads  a file over HTTP. zsync uses a control file to determine whether any blocks in the file are already known to the downloader, and
       only downloads the new blocks.

       Either a filename or a URL can be given on the command line - this is the path of the control file for the download, which normally has the
       name  of  the actual file to downlaod with .zsync appended. (To create this .zsync file you have to have a copy of the target file, so this
       file should be generated by the person providing the download).

       zsync downloads to your current directory. It looks for any file in the directory of the same name as the file to  download.  If  it  finds
       one,  it  assumes that this is an earlier or incomplete version of the new file to download, and scans this file for any blocks that it can
       use to build the target file. (It also looks for a file of the same name with .part appended, so  it  will  automatically  find	previously
       interrupted  zsync  downloads  and reuse the data already downloaded. If you know that the local file to use as input has a different name,
       you must use -i)

       zsync retrieves the rest of the target file over HTTP. Once the download is finished, the old version (if the new file wants the same name)
       is  moved  aside  (a  .zs-old extension is appended). The modification time of the file is set to be the same as the remote source file (if
       specified in the .zsync).

OPTIONS

       -A hostname=username:password
	      Specifies a username and password to be used with the given hostname. -A can be used multiple times (with different  hostnames),	in
	      cases where e.g. the
	       .zsync  file  is  on  a	different  server from the download, or there are multiple download servers (there could be different auth
	      details for different servers - and zsync never assumes that your password should be sent to a server other than	the  one  named  -
	      otherwise redirects would be dangerous!).

       -i inputfile
	      Specifies  (extra)  input  files.  inputfile  is scanned to identify blocks in common with the target file and zsync uses any blocks
	      found. Can be used multiple times.

       -k file.zsync
	      Indicates that zsync should save the zsync file that it downloads, with the given filename. If that file already exists, then  zsync
	      will  make  a  conditional  request to the web server, such that it will only download it again if the server's copy is newer. zsync
	      will append .part to the filename for storing it while it is downloading, and will only overwrite the main file once the download is
	      done - and if the download is interrupted, it will resume using the data in the .part file.

       -o outputfile
	      Override the default output file name.

       -q     Suppress the progress bar, download rate and ETA display.

       -s     Deprecated synonym for -q.

       -u url This  specifies  the  referring  URL.   If  you have a .zsync file locally (if you downloaded it separately, with wget, say) and the
	      .zsync file contains a relative URL, you need to specify where you got the .zsync file from so that zsync  knows	which  server  and
	      path to use for the rest of the download (this is analogous to adding a <base href="..."> to a downloaded web page to make the links
	      work).

       -V     Prints the version of zsync.

FILES

ENVIRONMENT VARIABLES

       http_proxy
	      Should be the [http://]hostname:port for your web proxy, if one is required to access the target web server(s).

EXAMPLES

       zsync -i /var/lib/apt/lists/server.debian.org_debian_dists_etch_main_binary-i386_Packages http://zsync.moria.org.uk/s/etch/Packages.zsync

AUTHORS

       Colin Phipps <cph@moria.org.uk>

SEE ALSO

       zsyncmake(1)

Colin Phipps							       0.6.2								  zsync(1)