Ubuntu Manpage: zsync - Partial/differential file download client over HTTP

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>