zsync

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  ac‐
   tual  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  down‐
   loaded. 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 condi‐
          tional 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 re‐
          sume 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>