This is Info file wget.info, produced by Makeinfo version 1.68 from the
input file ./wget.texi.
INFO-DIR-SECTION Net Utilities
INFO-DIR-SECTION World Wide Web
START-INFO-DIR-ENTRY
* Wget: (wget). The non-interactive network downloader.
END-INFO-DIR-ENTRY
This file documents the the GNU Wget utility for downloading network
data.
Copyright (C) 1996, 1997, 1998, 2000 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the sections entitled "Copying" and "GNU General Public License"
are included exactly as in the original, and provided that the entire
resulting derived work is distributed under the terms of a permission
notice identical to this one.
File: wget.info, Node: Top, Next: Overview, Prev: (dir), Up: (dir)
Wget 1.5.3+dev
**************
This manual documents version 1.5.3+dev of GNU Wget, the freely
available utility for network download.
Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
* Menu:
* Overview:: Features of Wget.
* Invoking:: Wget command-line arguments.
* Recursive Retrieval:: Description of recursive retrieval.
* Following Links:: The available methods of chasing links.
* Time-Stamping:: Mirroring according to time-stamps.
* Startup File:: Wget's initialization file.
* Examples:: Examples of usage.
* Various:: The stuff that doesn't fit anywhere else.
* Appendices:: Some useful references.
* Copying:: You may give out copies of Wget.
* Concept Index:: Topics covered by this manual.
File: wget.info, Node: Overview, Next: Invoking, Prev: Top, Up: Top
Overview
********
GNU Wget is a freely available network utility to retrieve files from
the World Wide Web, using HTTP (Hyper Text Transfer Protocol) and FTP
(File Transfer Protocol), the two most widely used Internet protocols.
It has many useful features to make downloading easier, some of them
being:
* 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 is capable of descending recursively through the structure of
HTML documents and FTP directory trees, making a local copy of the
directory hierarchy similar to the one on the remote server. This
feature can be used to mirror archives and home pages, or traverse
the web in search of data, like a WWW robot (*Note Robots::). In
that spirit, Wget understands the `norobots' convention.
* 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 works exceedingly well on slow or unstable connections,
retrying the document until it is fully retrieved, or until a
user-specified retry count is surpassed. It will try to resume the
download from the point of interruption, using `REST' with FTP and
`Range' with HTTP servers that support them.
* By default, Wget supports proxy servers, which can lighten the
network load, speed up retrieval and provide access behind
firewalls. However, if you are behind a firewall that requires
that you use a socks style gateway, you can get the socks library
and build wget with support for socks. Wget also supports the
passive FTP downloading as an option.
* Builtin features offer mechanisms to tune which links you wish to
follow (*Note Following Links::).
* The retrieval is conveniently traced with printing dots, each dot
representing a fixed amount of data received (1KB by default).
These representations can be customized to your preferences.
* Most of the features are fully configurable, either through
command line options, or via the initialization file `.wgetrc'
(*Note Startup File::). Wget allows you to define "global"
startup files (`/usr/local/etc/wgetrc' by default) for site
settings.
* 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 (*Note Copying::).
File: wget.info, Node: Invoking, Next: Recursive Retrieval, Prev: Overview, Up: Top
Invoking
********
By default, Wget is very simple to invoke. The basic syntax is:
wget [OPTION]... [URL]...
Wget will simply download all the URLs specified on the command
line. URL is a "Uniform Resource Locator", as defined below.
However, you may wish to change some of the default parameters of
Wget. You can do it two ways: permanently, adding the appropriate
command to `.wgetrc' (*Note Startup File::), or specifying it on the
command line.
* Menu:
* URL Format::
* Option Syntax::
* Basic Startup Options::
* Logging and Input File Options::
* Download Options::
* Directory Options::
* HTTP Options::
* FTP Options::
* Recursive Retrieval Options::
* Recursive Accept/Reject Options::
File: wget.info, Node: URL Format, Next: Option Syntax, Prev: Invoking, Up: Invoking
URL Format
==========
"URL" is an acronym for Uniform Resource Locator. A uniform
resource locator is a compact string representation for a resource
available via the Internet. Wget recognizes the URL syntax as per
RFC1738. This is the most widely used form (square brackets denote
optional parts):
http://host[:port]/directory/file
ftp://host[:port]/directory/file
You can also encode your username and password within a URL:
ftp://user:password@host/path
http://user:password@host/path
Either USER or PASSWORD, or both, may be left out. If you leave out
either the HTTP username or password, no authentication will be sent.
If you leave out the FTP username, `anonymous' will be used. If you
leave out the FTP password, your email address will be supplied as a
default password.(1)
You can encode unsafe characters in a URL as `%xy', `xy' being the
hexadecimal representation of the character's ASCII value. Some common
unsafe characters include `%' (quoted as `%25'), `:' (quoted as `%3A'),
and `@' (quoted as `%40'). Refer to RFC1738 for a comprehensive list
of unsafe characters.
Wget also supports the `type' feature for FTP URLs. By default, FTP
documents are retrieved in the binary mode (type `i'), which means that
they are downloaded unchanged. Another useful mode is the `a'
("ASCII") mode, which converts the line delimiters between the
different operating systems, and is thus useful for text files. Here
is an example:
ftp://host/directory/file;type=a
Two alternative variants of URL specification are also supported,
because of historical (hysterical?) reasons and their widespreaded use.
FTP-only syntax (supported by `NcFTP'):
host:/dir/file
HTTP-only syntax (introduced by `Netscape'):
host[:port]/dir/file
These two alternative forms are deprecated, and may cease being
supported in the future.
If you do not understand the difference between these notations, or
do not know which one to use, just use the plain ordinary format you use
with your favorite browser, like `Lynx' or `Netscape'.
---------- Footnotes ----------
(1) If you have a `.netrc' file in your home directory, password
will also be searched for there.
File: wget.info, Node: Option Syntax, Next: Basic Startup Options, Prev: URL Format, Up: Invoking
Option Syntax
=============
Since Wget uses GNU getopts to process its arguments, every option
has a short form and a long form. Long options are more convenient to
remember, but take time to type. You may freely mix different option
styles, or specify options after the command-line arguments. Thus you
may write:
wget -r --tries=10 http://fly.cc.fer.hr/ -o log
The space between the option accepting an argument and the argument
may be omitted. Instead `-o log' you can write `-olog'.
You may put several options that do not require arguments together,
like:
wget -drc URL
This is a complete equivalent of:
wget -d -r -c URL
Since the options can be specified after the arguments, you may
terminate them with `--'. So the following will try to download URL
`-x', reporting failure to `log':
wget -o log -- -x
The options that accept comma-separated lists all respect the
convention that specifying an empty list clears its value. This can be
useful to clear the `.wgetrc' settings. For instance, if your `.wgetrc'
sets `exclude_directories' to `/cgi-bin', the following example will
first reset it, and then set it to exclude `/~nobody' and `/~somebody'.
You can also clear the lists in `.wgetrc' (*Note Wgetrc Syntax::).
wget -X '' -X /~nobody,/~somebody
File: wget.info, Node: Basic Startup Options, Next: Logging and Input File Options, Prev: Option Syntax, Up: Invoking
Basic Startup Options
=====================
`-V'
`--version'
Display the version of Wget.
`-h'
`--help'
Print a help message describing all of Wget's command-line options.
`-b'
`--background'
Go to background immediately after startup. If no output file is
specified via the `-o', output is redirected to `wget-log'.
`-e COMMAND'
`--execute COMMAND'
Execute COMMAND as if it were a part of `.wgetrc' (*Note Startup
File::). A command thus invoked will be executed *after* the
commands in `.wgetrc', thus taking precedence over them.
File: wget.info, Node: Logging and Input File Options, Next: Download Options, Prev: Basic Startup Options, Up: Invoking
Logging and Input File Options
==============================
`-o LOGFILE'
`--output-file=LOGFILE'
Log all messages to LOGFILE. The messages are normally reported
to standard error.
`-a LOGFILE'
`--append-output=LOGFILE'
Append to LOGFILE. This is the same as `-o', only it appends to
LOGFILE instead of overwriting the old log file. If LOGFILE does
not exist, a new file is created.
`-d'
`--debug'
Turn on debug output, meaning various information important to the
developers of Wget if it does not work properly. Your system
administrator may have chosen to compile Wget without debug
support, in which case `-d' will not work. Please note that
compiling with debug support is always safe--Wget compiled with
the debug support will *not* print any debug info unless requested
with `-d'. *Note Reporting Bugs:: for more information on how to
use `-d' for sending bug reports.
`-q'
`--quiet'
Turn off Wget's output.
`-v'
`--verbose'
Turn on verbose output, with all the available data. The default
output is verbose.
`-nv'
`--non-verbose'
Non-verbose output--turn off verbose without being completely quiet
(use `-q' for that), which means that error messages and basic
information still get printed.
`-i FILE'
`--input-file=FILE'
Read URLs from FILE, in which case no URLs need to be on the
command line. If there are URLs both on the command line and in
an input file, those on the command lines will be the first ones to
be retrieved. The FILE need not be an HTML document (but no harm
if it is)--it is enough if the URLs are just listed sequentially.
However, if you specify `--force-html', the document will be
regarded as `html'. In that case you may have problems with
relative links, which you can solve either by adding `' to the documents or by specifying `--base=URL' on the
command line.
`-F'
`--force-html'
When input is read from a file, force it to be treated as an HTML
file. This enables you to retrieve relative links from existing
HTML files on your local disk, by adding `' to
HTML, or using the `--base' command-line option.
File: wget.info, Node: Download Options, Next: Directory Options, Prev: Logging and Input File Options, Up: Invoking
Download Options
================
`-t NUMBER'
`--tries=NUMBER'
Set number of retries to NUMBER. Specify 0 or `inf' for infinite
retrying.
`-O FILE'
`--output-document=FILE'
The documents will not be written to the appropriate files, but
all will be concatenated together and written to FILE. If FILE
already exists, it will be overwritten. If the FILE is `-', the
documents will be written to standard output. Including this
option automatically sets the number of tries to 1.
`-nc'
`--no-clobber'
Do not clobber existing files when saving to directory hierarchy
within recursive retrieval of several files. This option is
*extremely* useful when you wish to continue where you left off
with retrieval of many files. If the files have the `.html' or
(yuck) `.htm' suffix, they will be loaded from the local disk, and
parsed as if they have been retrieved from the Web.
`-c'
`--continue'
Continue getting an existing file. This is useful when you want to
finish up the download started by another program, or a previous
instance of Wget. Thus you can write:
wget -c ftp://sunsite.doc.ic.ac.uk/ls-lR.Z
If there is a file name `ls-lR.Z' in the current directory, Wget
will assume that it is the first portion of the remote file, and
will require the server to continue the retrieval from an offset
equal to the length of the local file.
Note that you need not specify this option if all you want is Wget
to continue retrieving where it left off when the connection is
lost--Wget does this by default. You need this option only when
you want to continue retrieval of a file already halfway
retrieved, saved by another FTP client, or left by Wget being
killed.
Without `-c', the previous example would just begin to download the
remote file to `ls-lR.Z.1'. The `-c' option is also applicable
for HTTP servers that support the `Range' header.
`--dot-style=STYLE'
Set the retrieval style to STYLE. Wget traces the retrieval of
each document by printing dots on the screen, each dot
representing a fixed amount of retrieved data. Any number of dots
may be separated in a "cluster", to make counting easier. This
option allows you to choose one of the pre-defined styles,
determining the number of bytes represented by a dot, the number
of dots in a cluster, and the number of dots on the line.
With the `default' style each dot represents 1K, there are ten dots
in a cluster and 50 dots in a line. The `binary' style has a more
"computer"-like orientation--8K dots, 16-dots clusters and 48 dots
per line (which makes for 384K lines). The `mega' style is
suitable for downloading very large files--each dot represents 64K
retrieved, there are eight dots in a cluster, and 48 dots on each
line (so each line contains 3M). The `micro' style is exactly the
reverse; it is suitable for downloading small files, with 128-byte
dots, 8 dots per cluster, and 48 dots (6K) per line.
`-N'
`--timestamping'
Turn on time-stamping. *Note Time-Stamping:: for details.
`-S'
`--server-response'
Print the headers sent by HTTP servers and responses sent by FTP
servers.
`--spider'
When invoked with this option, Wget will behave as a Web "spider",
which means that it will not download the pages, just check that
they are there. You can use it to check your bookmarks, e.g. with:
wget --spider --force-html -i bookmarks.html
This feature needs much more work for Wget to get close to the
functionality of real WWW spiders.
`-T seconds'
`--timeout=SECONDS'
Set the read timeout to SECONDS seconds. Whenever a network read
is issued, the file descriptor is checked for a timeout, which
could otherwise leave a pending connection (uninterrupted read).
The default timeout is 900 seconds (fifteen minutes). Setting
timeout to 0 will disable checking for timeouts.
Please do not lower the default timeout value with this option
unless you know what you are doing.
`-w SECONDS'
`--wait=SECONDS'
Wait the specified number of seconds between the retrievals. Use
of this option is recommended, as it lightens the server load by
making the requests less frequent. Instead of in seconds, the
time can be specified in minutes using the `m' suffix, in hours
using `h' suffix, or in days using `d' suffix.
Specifying a large value for this option is useful if the network
or the destination host is down, so that Wget can wait long enough
to reasonably expect the network error to be fixed before the
retry.
`--waitretry=SECONDS'
If you don't want Wget to wait between *every* retrieval, but only
between retries of failed downloads, you can use this option.
Wget will use "linear backoff", waiting 1 second after the first
failure on a given file, then waiting 2 seconds after the second
failure on that file, up to the maximum number of SECONDS you
specify. Therefore, a value of 10 will actually make Wget wait up
to (1 + 2 + ... + 10) = 55 seconds per file.
Note that this option is turned on by default in the global
`wgetrc' file.
`-Y on/off'
`--proxy=on/off'
Turn proxy support on or off. The proxy is on by default if the
appropriate environmental variable is defined.
`-Q QUOTA'
`--quota=QUOTA'
Specify download quota for automatic retrievals. The value can be
specified in bytes (default), kilobytes (with `k' suffix), or
megabytes (with `m' suffix).
Note that quota will never affect downloading a single file. So
if you specify `wget -Q10k ftp://wuarchive.wustl.edu/ls-lR.gz',
all of the `ls-lR.gz' will be downloaded. The same goes even when
several URLs are specified on the command-line. However, quota is
respected when retrieving either recursively, or from an input
file. Thus you may safely type `wget -Q2m -i sites'--download
will be aborted when the quota is exceeded.
Setting quota to 0 or to `inf' unlimits the download quota.
File: wget.info, Node: Directory Options, Next: HTTP Options, Prev: Download Options, Up: Invoking
Directory Options
=================
`-nd'
`--no-directories'
Do not create a hierarchy of directories when retrieving
recursively. With this option turned on, all files will get saved
to the current directory, without clobbering (if a name shows up
more than once, the filenames will get extensions `.n').
`-x'
`--force-directories'
The opposite of `-nd'--create a hierarchy of directories, even if
one would not have been created otherwise. E.g. `wget -x
http://fly.cc.fer.hr/robots.txt' will save the downloaded file to
`fly.cc.fer.hr/robots.txt'.
`-nH'
`--no-host-directories'
Disable generation of host-prefixed directories. By default,
invoking Wget with `-r http://fly.cc.fer.hr/' will create a
structure of directories beginning with `fly.cc.fer.hr/'. This
option disables such behavior.
`--cut-dirs=NUMBER'
Ignore NUMBER directory components. This is useful for getting a
fine-grained control over the directory where recursive retrieval
will be saved.
Take, for example, the directory at
`ftp://ftp.xemacs.org/pub/xemacs/'. If you retrieve it with `-r',
it will be saved locally under `ftp.xemacs.org/pub/xemacs/'.
While the `-nH' option can remove the `ftp.xemacs.org/' part, you
are still stuck with `pub/xemacs'. This is where `--cut-dirs'
comes in handy; it makes Wget not "see" NUMBER remote directory
components. Here are several examples of how `--cut-dirs' option
works.
No options -> ftp.xemacs.org/pub/xemacs/
-nH -> pub/xemacs/
-nH --cut-dirs=1 -> xemacs/
-nH --cut-dirs=2 -> .
--cut-dirs=1 -> ftp.xemacs.org/xemacs/
...
If you just want to get rid of the directory structure, this
option is similar to a combination of `-nd' and `-P'. However,
unlike `-nd', `--cut-dirs' does not lose with subdirectories--for
instance, with `-nH --cut-dirs=1', a `beta/' subdirectory will be
placed to `xemacs/beta', as one would expect.
`-P PREFIX'
`--directory-prefix=PREFIX'
Set directory prefix to PREFIX. The "directory prefix" is the
directory where all other files and subdirectories will be saved
to, i.e. the top of the retrieval tree. The default is `.' (the
current directory).
File: wget.info, Node: HTTP Options, Next: FTP Options, Prev: Directory Options, Up: Invoking
HTTP Options
============
`--http-user=USER'
`--http-passwd=PASSWORD'
Specify the username USER and password PASSWORD on an HTTP server.
According to the type of the challenge, Wget will encode them
using either the `basic' (insecure) or the `digest' authentication
scheme.
Another way to specify username and password is in the URL itself
(*Note URL Format::). For more information about security issues
with Wget, *Note Security Considerations::.
`-C on/off'
`--cache=on/off'
When set to off, disable server-side cache. In this case, Wget
will send the remote server an appropriate directive (`Pragma:
no-cache') to get the file from the remote service, rather than
returning the cached version. This is especially useful for
retrieving and flushing out-of-date documents on proxy servers.
Caching is allowed by default.
`--ignore-length'
Unfortunately, some HTTP servers (CGI programs, to be more
precise) send out bogus `Content-Length' headers, which makes Wget
go wild, as it thinks not all the document was retrieved. You can
spot this syndrome if Wget retries getting the same document again
and again, each time claiming that the (otherwise normal)
connection has closed on the very same byte.
With this option, Wget will ignore the `Content-Length' header--as
if it never existed.
`--header=ADDITIONAL-HEADER'
Define an ADDITIONAL-HEADER to be passed to the HTTP servers.
Headers must contain a `:' preceded by one or more non-blank
characters, and must not contain newlines.
You may define more than one additional header by specifying
`--header' more than once.
wget --header='Accept-Charset: iso-8859-2' \
--header='Accept-Language: hr' \
http://fly.cc.fer.hr/
Specification of an empty string as the header value will clear all
previous user-defined headers.
`--proxy-user=USER'
`--proxy-passwd=PASSWORD'
Specify the username USER and password PASSWORD for authentication
on a proxy server. Wget will encode them using the `basic'
authentication scheme.
`--referer=URL'
Include `Referer: URL' header in HTTP request. Useful for
retrieving documents with server-side processing that assume they
are always being retrieved by interactive web browsers and only
come out properly when Referer is set to one of the pages that
point to them.
`-s'
`--save-headers'
Save the headers sent by the HTTP server to the file, preceding the
actual contents, with an empty line as the separator.
`-U AGENT-STRING'
`--user-agent=AGENT-STRING'
Identify as AGENT-STRING to the HTTP server.
The HTTP protocol allows the clients to identify themselves using a
`User-Agent' header field. This enables distinguishing the WWW
software, usually for statistical purposes or for tracing of
protocol violations. Wget normally identifies as `Wget/VERSION',
VERSION being the current version number of Wget.
However, some sites have been known to impose the policy of
tailoring the output according to the `User-Agent'-supplied
information. While conceptually this is not such a bad idea, it
has been abused by servers denying information to clients other
than `Mozilla' or Microsoft `Internet Explorer'. This option
allows you to change the `User-Agent' line issued by Wget. Use of
this option is discouraged, unless you really know what you are
doing.
*NOTE* that Netscape Communications Corp. has claimed that false
transmissions of `Mozilla' as the `User-Agent' are a copyright
infringement, which will be prosecuted. *DO NOT* misrepresent
Wget as Mozilla.
File: wget.info, Node: FTP Options, Next: Recursive Retrieval Options, Prev: HTTP Options, Up: Invoking
FTP Options
===========
`--retr-symlinks'
Retrieve symbolic links on FTP sites as if they were plain files,
i.e. don't just create links locally.
`-g on/off'
`--glob=on/off'
Turn FTP globbing on or off. Globbing means you may use the
shell-like special characters ("wildcards"), like `*', `?', `['
and `]' to retrieve more than one file from the same directory at
once, like:
wget ftp://gnjilux.cc.fer.hr/*.msg
By default, globbing will be turned on if the URL contains a
globbing character. This option may be used to turn globbing on
or off permanently.
You may have to quote the URL to protect it from being expanded by
your shell. Globbing makes Wget look for a directory listing,
which is system-specific. This is why it currently works only
with Unix FTP servers (and the ones emulating Unix `ls' output).
`--passive-ftp'
Use the "passive" FTP retrieval scheme, in which the client
initiates the data connection. This is sometimes required for FTP
to work behind firewalls.
File: wget.info, Node: Recursive Retrieval Options, Next: Recursive Accept/Reject Options, Prev: FTP Options, Up: Invoking
Recursive Retrieval Options
===========================
`-r'
`--recursive'
Turn on recursive retrieving. *Note Recursive Retrieval:: for more
details.
`-l DEPTH'
`--level=DEPTH'
Specify recursion maximum depth level DEPTH (*Note Recursive
Retrieval::). The default maximum depth is 5.
`--delete-after'
This option tells Wget to delete every single file it downloads,
*after* having done so. It is useful for pre-fetching popular
pages through proxy, e.g.:
wget -r -nd --delete-after http://whatever.com/~popular/page/
The `-r' option is to retrieve recursively, and `-nd' not to
create directories.
`-k'
`--convert-links'
Convert the non-relative links to relative ones locally. Only the
references to the documents actually downloaded will be converted;
the rest will be left unchanged.
Note that only at the end of the download can Wget know which
links have been downloaded. Because of that, much of the work
done by `-k' will be performed at the end of the downloads.
`-K'
`--backup-converted'
When converting a file, back up the original version with a `.orig'
suffix. Affects the behavior of `-N' (*Note HTTP Time-Stamping
Internals::).
`-m'
`--mirror'
Turn on options suitable for mirroring. This option turns on
recursion and time-stamping, sets infinite recursion depth and
keeps FTP directory listings. It is currently equivalent to `-r
-N -l inf -nr'.
`-nr'
`--dont-remove-listing'
Don't remove the temporary `.listing' files generated by FTP
retrievals. Normally, these files contain the raw directory
listings received from FTP servers. Not removing them can be
useful to access the full remote file list when running a mirror,
or for debugging purposes.
File: wget.info, Node: Recursive Accept/Reject Options, Prev: Recursive Retrieval Options, Up: Invoking
Recursive Accept/Reject Options
===============================
`-A ACCLIST --accept ACCLIST'
`-R REJLIST --reject REJLIST'
Specify comma-separated lists of file name suffixes or patterns to
accept or reject (*Note Types of Files:: for more details).
`-D DOMAIN-LIST'
`--domains=DOMAIN-LIST'
Set domains to be accepted and DNS looked-up, where DOMAIN-LIST is
a comma-separated list. Note that it does *not* turn on `-H'.
This option speeds things up, even if only one host is spanned
(*Note Domain Acceptance::).
`--exclude-domains DOMAIN-LIST'
Exclude the domains given in a comma-separated DOMAIN-LIST from
DNS-lookup (*Note Domain Acceptance::).
`--follow-ftp'
Follow FTP links from HTML documents. Without this option, Wget
will ignore all the FTP links.
`--follow-tags=LIST'
Wget has an internal table of HTML tag / attribute pairs that it
considers when looking for linked documents during a recursive
retrieval. If a user wants only a subset of those tags to be
considered, however, he or she should be specify such tags in a
comma-separated LIST with this option.
`-G LIST'
`--ignore-tags=LIST'
This is the opposite of the `--follow-tags' option. To skip
certain HTML tags when recursively looking for documents to
download, specify them in a comma-separated LIST. The author of
this option likes to use the following command to download a
single HTML page and all documents necessary to display it
properly:
wget -Ga,area -H -k -K -nh -r http://SITE/DOCUMENT
`-H'
`--span-hosts'
Enable spanning across hosts when doing recursive retrieving
(*Note All Hosts::).
`-L'
`--relative'
Follow relative links only. Useful for retrieving a specific home
page without any distractions, not even those from the same hosts
(*Note Relative Links::).
`-I LIST'
`--include-directories=LIST'
Specify a comma-separated list of directories you wish to follow
when downloading (*Note Directory-Based Limits:: for more
details.) Elements of LIST may contain wildcards.
`-X LIST'
`--exclude-directories=LIST'
Specify a comma-separated list of directories you wish to exclude
from download (*Note Directory-Based Limits:: for more details.)
Elements of LIST may contain wildcards.
`-nh'
`--no-host-lookup'
Disable the time-consuming DNS lookup of almost all hosts (*Note
Host Checking::).
`-np'
`--no-parent'
Do not ever ascend to the parent directory when retrieving
recursively. This is a useful option, since it guarantees that
only the files *below* a certain hierarchy will be downloaded.
*Note Directory-Based Limits:: for more details.
File: wget.info, Node: Recursive Retrieval, Next: Following Links, Prev: Invoking, Up: Top
Recursive Retrieval
*******************
GNU Wget is capable of traversing parts of the Web (or a single HTTP
or FTP server), depth-first following links and directory structure.
This is called "recursive" retrieving, or "recursion".
With HTTP URLs, Wget retrieves and parses the HTML from the given
URL, documents, retrieving the files the HTML document was referring
to, through markups like `href', or `src'. If the freshly downloaded
file is also of type `text/html', it will be parsed and followed
further.
The maximum "depth" to which the retrieval may descend is specified
with the `-l' option (the default maximum depth is five layers). *Note
Recursive Retrieval::.
When retrieving an FTP URL recursively, Wget will retrieve all the
data from the given directory tree (including the subdirectories up to
the specified depth) on the remote server, creating its mirror image
locally. FTP retrieval is also limited by the `depth' parameter.
By default, Wget will create a local directory tree, corresponding to
the one found on the remote server.
Recursive retrieving can find a number of applications, the most
important of which is mirroring. It is also useful for WWW
presentations, and any other opportunities where slow network
connections should be bypassed by storing the files locally.
You should be warned that invoking recursion may cause grave
overloading on your system, because of the fast exchange of data
through the network; all of this may hamper other users' work. The
same stands for the foreign server you are mirroring--the more requests
it gets in a rows, the greater is its load.
Careless retrieving can also fill your file system uncontrollably,
which can grind the machine to a halt.
The load can be minimized by lowering the maximum recursion level
(`-l') and/or by lowering the number of retries (`-t'). You may also
consider using the `-w' option to slow down your requests to the remote
servers, as well as the numerous options to narrow the number of
followed links (*Note Following Links::).
Recursive retrieval is a good thing when used properly. Please take
all precautions not to wreak havoc through carelessness.
File: wget.info, Node: Following Links, Next: Time-Stamping, Prev: Recursive Retrieval, Up: Top
Following Links
***************
When retrieving recursively, one does not wish to retrieve loads of
unnecessary data. Most of the time the users bear in mind exactly what
they want to download, and want Wget to follow only specific links.
For example, if you wish to download the music archive from
`fly.cc.fer.hr', you will not want to download all the home pages that
happen to be referenced by an obscure part of the archive.
Wget possesses several mechanisms that allows you to fine-tune which
links it will follow.
* Menu:
* Relative Links:: Follow relative links only.
* Host Checking:: Follow links on the same host.
* Domain Acceptance:: Check on a list of domains.
* All Hosts:: No host restrictions.
* Types of Files:: Getting only certain files.
* Directory-Based Limits:: Getting only certain directories.
* FTP Links:: Following FTP links.
File: wget.info, Node: Relative Links, Next: Host Checking, Prev: Following Links, Up: Following Links
Relative Links
==============
When only relative links are followed (option `-L'), recursive
retrieving will never span hosts. No time-expensive DNS-lookups will
be performed, and the process will be very fast, with the minimum
strain of the network. This will suit your needs often, especially when
mirroring the output of various `x2html' converters, since they
generally output relative links.
File: wget.info, Node: Host Checking, Next: Domain Acceptance, Prev: Relative Links, Up: Following Links
Host Checking
=============
The drawback of following the relative links solely is that humans
often tend to mix them with absolute links to the very same host, and
the very same page. In this mode (which is the default mode for
following links) all URLs that refer to the same host will be retrieved.
The problem with this option are the aliases of the hosts and
domains. Thus there is no way for Wget to know that `regoc.srce.hr' and
`www.srce.hr' are the same host, or that `fly.cc.fer.hr' is the same as
`fly.cc.etf.hr'. Whenever an absolute link is encountered, the host is
DNS-looked-up with `gethostbyname' to check whether we are maybe
dealing with the same hosts. Although the results of `gethostbyname'
are cached, it is still a great slowdown, e.g. when dealing with large
indices of home pages on different hosts (because each of the hosts
must be DNS-resolved to see whether it just *might* be an alias of the
starting host).
To avoid the overhead you may use `-nh', which will turn off
DNS-resolving and make Wget compare hosts literally. This will make
things run much faster, but also much less reliable (e.g. `www.srce.hr'
and `regoc.srce.hr' will be flagged as different hosts).
Note that modern HTTP servers allow one IP address to host several
"virtual servers", each having its own directory hierarchy. Such
"servers" are distinguished by their hostnames (all of which point to
the same IP address); for this to work, a client must send a `Host'
header, which is what Wget does. However, in that case Wget *must not*
try to divine a host's "real" address, nor try to use the same hostname
for each access, i.e. `-nh' must be turned on.
In other words, the `-nh' option must be used to enable the
retrieval from virtual servers distinguished by their hostnames. As the
number of such server setups grow, the behavior of `-nh' may become the
default in the future.
File: wget.info, Node: Domain Acceptance, Next: All Hosts, Prev: Host Checking, Up: Following Links
Domain Acceptance
=================
With the `-D' option you may specify the domains that will be
followed. The hosts the domain of which is not in this list will not be
DNS-resolved. Thus you can specify `-Dmit.edu' just to make sure that
*nothing outside of MIT gets looked up*. This is very important and
useful. It also means that `-D' does *not* imply `-H' (span all
hosts), which must be specified explicitly. Feel free to use this
options since it will speed things up, with almost all the reliability
of checking for all hosts. Thus you could invoke
wget -r -D.hr http://fly.cc.fer.hr/
to make sure that only the hosts in `.hr' domain get DNS-looked-up
for being equal to `fly.cc.fer.hr'. So `fly.cc.etf.hr' will be checked
(only once!) and found equal, but `www.gnu.ai.mit.edu' will not even be
checked.
Of course, domain acceptance can be used to limit the retrieval to
particular domains with spanning of hosts in them, but then you must
specify `-H' explicitly. E.g.:
wget -r -H -Dmit.edu,stanford.edu http://www.mit.edu/
will start with `http://www.mit.edu/', following links across MIT
and Stanford.
If there are domains you want to exclude specifically, you can do it
with `--exclude-domains', which accepts the same type of arguments of
`-D', but will *exclude* all the listed domains. For example, if you
want to download all the hosts from `foo.edu' domain, with the
exception of `sunsite.foo.edu', you can do it like this:
wget -rH -Dfoo.edu --exclude-domains sunsite.foo.edu http://www.foo.edu/
File: wget.info, Node: All Hosts, Next: Types of Files, Prev: Domain Acceptance, Up: Following Links
All Hosts
=========
When `-H' is specified without `-D', all hosts are freely spanned.
There are no restrictions whatsoever as to what part of the net Wget
will go to fetch documents, other than maximum retrieval depth. If a
page references `www.yahoo.com', so be it. Such an option is rarely
useful for itself.
File: wget.info, Node: Types of Files, Next: Directory-Based Limits, Prev: All Hosts, Up: Following Links
Types of Files
==============
When downloading material from the web, you will often want to
restrict the retrieval to only certain file types. For example, if you
are interested in downloading GIFs, you will not be overjoyed to get
loads of PostScript documents, and vice versa.
Wget offers two options to deal with this problem. Each option
description lists a short name, a long name, and the equivalent command
in `.wgetrc'.
`-A ACCLIST'
`--accept ACCLIST'
`accept = ACCLIST'
The argument to `--accept' option is a list of file suffixes or
patterns that Wget will download during recursive retrieval. A
suffix is the ending part of a file, and consists of "normal"
letters, e.g. `gif' or `.jpg'. A matching pattern contains
shell-like wildcards, e.g. `books*' or `zelazny*196[0-9]*'.
So, specifying `wget -A gif,jpg' will make Wget download only the
files ending with `gif' or `jpg', i.e. GIFs and JPEGs. On the
other hand, `wget -A "zelazny*196[0-9]*"' will download only files
beginning with `zelazny' and containing numbers from 1960 to 1969
anywhere within. Look up the manual of your shell for a
description of how pattern matching works.
Of course, any number of suffixes and patterns can be combined
into a comma-separated list, and given as an argument to `-A'.
`-R REJLIST'
`--reject REJLIST'
`reject = REJLIST'
The `--reject' option works the same way as `--accept', only its
logic is the reverse; Wget will download all files *except* the
ones matching the suffixes (or patterns) in the list.
So, if you want to download a whole page except for the cumbersome
MPEGs and .AU files, you can use `wget -R mpg,mpeg,au'.
Analogously, to download all files except the ones beginning with
`bjork', use `wget -R "bjork*"'. The quotes are to prevent
expansion by the shell.
The `-A' and `-R' options may be combined to achieve even better
fine-tuning of which files to retrieve. E.g. `wget -A "*zelazny*" -R
.ps' will download all the files having `zelazny' as a part of their
name, but *not* the PostScript files.
Note that these two options do not affect the downloading of HTML
files; Wget must load all the HTMLs to know where to go at
all--recursive retrieval would make no sense otherwise.
File: wget.info, Node: Directory-Based Limits, Next: FTP Links, Prev: Types of Files, Up: Following Links
Directory-Based Limits
======================
Regardless of other link-following facilities, it is often useful to
place the restriction of what files to retrieve based on the directories
those files are placed in. There can be many reasons for this--the
home pages may be organized in a reasonable directory structure; or some
directories may contain useless information, e.g. `/cgi-bin' or `/dev'
directories.
Wget offers three different options to deal with this requirement.
Each option description lists a short name, a long name, and the
equivalent command in `.wgetrc'.
`-I LIST'
`--include LIST'
`include_directories = LIST'
`-I' option accepts a comma-separated list of directories included
in the retrieval. Any other directories will simply be ignored.
The directories are absolute paths.
So, if you wish to download from `http://host/people/bozo/'
following only links to bozo's colleagues in the `/people'
directory and the bogus scripts in `/cgi-bin', you can specify:
wget -I /people,/cgi-bin http://host/people/bozo/
`-X LIST'
`--exclude LIST'
`exclude_directories = LIST'
`-X' option is exactly the reverse of `-I'--this is a list of
directories *excluded* from the download. E.g. if you do not want
Wget to download things from `/cgi-bin' directory, specify `-X
/cgi-bin' on the command line.
The same as with `-A'/`-R', these two options can be combined to
get a better fine-tuning of downloading subdirectories. E.g. if
you want to load all the files from `/pub' hierarchy except for
`/pub/worthless', specify `-I/pub -X/pub/worthless'.
`-np'
`--no-parent'
`no_parent = on'
The simplest, and often very useful way of limiting directories is
disallowing retrieval of the links that refer to the hierarchy
"above" than the beginning directory, i.e. disallowing ascent to
the parent directory/directories.
The `--no-parent' option (short `-np') is useful in this case.
Using it guarantees that you will never leave the existing
hierarchy. Supposing you issue Wget with:
wget -r --no-parent http://somehost/~luzer/my-archive/
You may rest assured that none of the references to
`/~his-girls-homepage/' or `/~luzer/all-my-mpegs/' will be
followed. Only the archive you are interested in will be
downloaded. Essentially, `--no-parent' is similar to
`-I/~luzer/my-archive', only it handles redirections in a more
intelligent fashion.
File: wget.info, Node: FTP Links, Prev: Directory-Based Limits, Up: Following Links
Following FTP Links
===================
The rules for FTP are somewhat specific, as it is necessary for them
to be. FTP links in HTML documents are often included for purposes of
reference, and it is often inconvenient to download them by default.
To have FTP links followed from HTML documents, you need to specify
the `--follow-ftp' option. Having done that, FTP links will span hosts
regardless of `-H' setting. This is logical, as FTP links rarely point
to the same host where the HTTP server resides. For similar reasons,
the `-L' options has no effect on such downloads. On the other hand,
domain acceptance (`-D') and suffix rules (`-A' and `-R') apply
normally.
Also note that followed links to FTP directories will not be
retrieved recursively further.
File: wget.info, Node: Time-Stamping, Next: Startup File, Prev: Following Links, Up: Top
Time-Stamping
*************
One of the most important aspects of mirroring information from the
Internet is updating your archives.
Downloading the whole archive again and again, just to replace a few
changed files is expensive, both in terms of wasted bandwidth and money,
and the time to do the update. This is why all the mirroring tools
offer the option of incremental updating.
Such an updating mechanism means that the remote server is scanned in
search of "new" files. Only those new files will be downloaded in the
place of the old ones.
A file is considered new if one of these two conditions are met:
1. A file of that name does not already exist locally.
2. A file of that name does exist, but the remote file was modified
more recently than the local file.
To implement this, the program needs to be aware of the time of last
modification of both remote and local files. Such information are
called the "time-stamps".
The time-stamping in GNU Wget is turned on using `--timestamping'
(`-N') option, or through `timestamping = on' directive in `.wgetrc'.
With this option, for each file it intends to download, Wget will check
whether a local file of the same name exists. If it does, and the
remote file is older, Wget will not download it.
If the local file does not exist, or the sizes of the files do not
match, Wget will download the remote file no matter what the time-stamps
say.
* Menu:
* Time-Stamping Usage::
* HTTP Time-Stamping Internals::
* FTP Time-Stamping Internals::
File: wget.info, Node: Time-Stamping Usage, Next: HTTP Time-Stamping Internals, Prev: Time-Stamping, Up: Time-Stamping
Time-Stamping Usage
===================
The usage of time-stamping is simple. Say you would like to
download a file so that it keeps its date of modification.
wget -S http://www.gnu.ai.mit.edu/
A simple `ls -l' shows that the time stamp on the local file equals
the state of the `Last-Modified' header, as returned by the server. As
you can see, the time-stamping info is preserved locally, even without
`-N'.
Several days later, you would like Wget to check if the remote file
has changed, and download it if it has.
wget -N http://www.gnu.ai.mit.edu/
Wget will ask the server for the last-modified date. If the local
file is newer, the remote file will not be re-fetched. However, if the
remote file is more recent, Wget will proceed fetching it normally.
The same goes for FTP. For example:
wget ftp://ftp.ifi.uio.no/pub/emacs/gnus/*
`ls' will show that the timestamps are set according to the state on
the remote server. Reissuing the command with `-N' will make Wget
re-fetch *only* the files that have been modified.
In both HTTP and FTP retrieval Wget will time-stamp the local file
correctly (with or without `-N') if it gets the stamps, i.e. gets the
directory listing for FTP or the `Last-Modified' header for HTTP.
If you wished to mirror the GNU archive every week, you would use the
following command every week:
wget --timestamping -r ftp://prep.ai.mit.edu/pub/gnu/
File: wget.info, Node: HTTP Time-Stamping Internals, Next: FTP Time-Stamping Internals, Prev: Time-Stamping Usage, Up: Time-Stamping
HTTP Time-Stamping Internals
============================
Time-stamping in HTTP is implemented by checking of the
`Last-Modified' header. If you wish to retrieve the file `foo.html'
through HTTP, Wget will check whether `foo.html' exists locally. If it
doesn't, `foo.html' will be retrieved unconditionally.
If the file does exist locally, Wget will first check its local
time-stamp (similar to the way `ls -l' checks it), and then send a
`HEAD' request to the remote server, demanding the information on the
remote file.
The `Last-Modified' header is examined to find which file was
modified more recently (which makes it "newer"). If the remote file is
newer, it will be downloaded; if it is older, Wget will give up.(1)
When `--backup-converted' (`-K') is specified in conjunction with
`-N', server file `X' is compared to local file `X.orig', if extant,
rather than being compared to local file `X', which will always differ
if it's been converted by `--convert-links' (`-k').
Arguably, HTTP time-stamping should be implemented using the
`If-Modified-Since' request.
---------- Footnotes ----------
(1) As an additional check, Wget will look at the `Content-Length'
header, and compare the sizes; if they are not the same, the remote
file will be downloaded no matter what the time-stamp says.