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)