wget: Overview
1 Overview
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GNU Wget is a free utility for non-interactive download of files from
the Web. It supports HTTP, HTTPS, and FTP protocols, as well as
retrieval through HTTP proxies.
This chapter is a partial overview of Wget’s features.
• Wget is non-interactive, meaning that it can work in the
background, while the user is not logged on. This allows you to
start a retrieval and disconnect from the system, letting Wget
finish the work. By contrast, most of the Web browsers require
constant user’s presence, which can be a great hindrance when
transferring a lot of data.
• Wget can follow links in HTML, XHTML, and CSS pages, to create
local versions of remote web sites, fully recreating the directory
structure of the original site. This is sometimes referred to as
“recursive downloading.” While doing that, Wget respects the Robot
Exclusion Standard (‘/robots.txt’). Wget can be instructed to
convert the links in downloaded files to point at the local files,
for offline viewing.
• File name wildcard matching and recursive mirroring of directories
are available when retrieving via FTP. Wget can read the
time-stamp information given by both HTTP and FTP servers, and
store it locally. Thus Wget can see if the remote file has changed
since last retrieval, and automatically retrieve the new version if
it has. This makes Wget suitable for mirroring of FTP sites, as
well as home pages.
• Wget has been designed for robustness over slow or unstable network
connections; if a download fails due to a network problem, it will
keep retrying until the whole file has been retrieved. If the
server supports regetting, it will instruct the server to continue
the download from where it left off.
• Wget supports proxy servers, which can lighten the network load,
speed up retrieval and provide access behind firewalls. Wget uses
the passive FTP downloading by default, active FTP being an option.
• Wget supports IP version 6, the next generation of IP. IPv6 is
autodetected at compile-time, and can be disabled at either build
or run time. Binaries built with IPv6 support work well in both
IPv4-only and dual family environments.
• Built-in features offer mechanisms to tune which links you wish to
follow (⇒Following Links).
• The progress of individual downloads is traced using a progress
gauge. Interactive downloads are tracked using a
“thermometer”-style gauge, whereas non-interactive ones are traced
with dots, each dot representing a fixed amount of data received
(1KB by default). Either gauge can be customized to your
preferences.
• Most of the features are fully configurable, either through command
line options, or via the initialization file ‘.wgetrc’ (⇒
Startup File). Wget allows you to define “global” startup files
(‘/etc/wgetrc’ by default) for site settings. You can also specify
the location of a startup file with the –config option. To disable
the reading of config files, use –no-config. If both –config and
–no-config are given, –no-config is ignored.
• Finally, GNU Wget is free software. This means that everyone may
use it, redistribute it and/or modify it under the terms of the GNU
General Public License, as published by the Free Software
Foundation (see the file ‘COPYING’ that came with GNU Wget, for
details).
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