Copyright © 1996–2005 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, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with the Invariant Sections being “GNU General Public License” and “GNU Free Documentation License”, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.
This manual documents version 1.10 of GNU Wget, the freely available utility for network downloads.
Copyright © 1996–2005 Free Software Foundation, Inc.
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.
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 (see Startup File), or specifying it on the command line.
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
Important Note: if you specify a password-containing url
on the command line, the username and password will be plainly visible
to all users on the system, by way of ps. On multi-user systems,
this is a big security risk. To work around it, use wget -i -
and feed the urls to Wget's standard input, each on a separate
line, terminated by C-d.
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.
Since Wget uses GNU getopt to process command-line arguments, every option has a long form along with the short one. 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.srk.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
(see Wgetrc Syntax).
wget -X '' -X /~nobody,/~somebody
Most options that do not accept arguments are boolean options, so named because their state can be captured with a yes-or-no (“boolean”) variable. For example, --follow-ftp tells Wget to follow FTP links from HTML files and, on the other hand, --no-glob tells it not to perform file globbing on FTP URLs. A boolean option is either affirmative or negative (beginning with --no). All such options share several properties.
Unless stated otherwise, it is assumed that the default behavior is the opposite of what the option accomplishes. For example, the documented existence of --follow-ftp assumes that the default is to not follow FTP links from HTML pages.
Affirmative options can be negated by prepending the --no- to
the option name; negative options can be negated by omitting the
--no- prefix. This might seem superfluous—if the default for
an affirmative option is to not do something, then why provide a way
to explicitly turn it off? But the startup file may in fact change
the default. For instance, using follow_ftp = off in
.wgetrc makes Wget not follow FTP links by default, and
using --no-follow-ftp is the only way to restore the factory
default from the command line.
If this function is used, no urls need be present 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 <base
href="url"> to the documents or by specifying
--base=url on the command line.
<base
href="url"> to html, or using the --base command-line
option.
Note that a combination with -k is only well-defined for downloading a single document.
When running Wget without -N, -nc, or -r,
downloading the same file in the same directory will result in the
original copy of file being preserved and the second copy being
named file.1. If that file is downloaded yet again, the
third copy will be named file.2, and so on. When
-nc is specified, this behavior is suppressed, and Wget will
refuse to download newer copies of file. Therefore,
“no-clobber” is actually a misnomer in this mode—it's not
clobbering that's prevented (as the numeric suffixes were already
preventing clobbering), but rather the multiple version saving that's
prevented.
When running Wget with -r, but without -N or -nc, re-downloading a file will result in the new copy simply overwriting the old. Adding -nc will prevent this behavior, instead causing the original version to be preserved and any newer copies on the server to be ignored.
When running Wget with -N, with or without -r, the decision as to whether or not to download a newer copy of a file depends on the local and remote timestamp and size of the file (see Time-Stamping). -nc may not be specified at the same time as -N.
Note that when -nc is specified, files with the suffixes .html or .htm will be loaded from the local disk and parsed as if they had been retrieved from the Web.
wget -c ftp://sunsite.doc.ic.ac.uk/ls-lR.Z
If there is a file named ls-lR.Z in the current directory, Wget will assume that it is the first portion of the remote file, and will ask the server to continue the retrieval from an offset equal to the length of the local file.
Note that you don't need to specify this option if you just want the current invocation of Wget to retry downloading a file should the connection be lost midway through. This is the default behavior. -c only affects resumption of downloads started prior to this invocation of Wget, and whose local files are still sitting around.
Without -c, the previous example would just download the remote file to ls-lR.Z.1, leaving the truncated ls-lR.Z file alone.
Beginning with Wget 1.7, if you use -c on a non-empty file, and it turns out that the server does not support continued downloading, Wget will refuse to start the download from scratch, which would effectively ruin existing contents. If you really want the download to start from scratch, remove the file.
Also beginning with Wget 1.7, if you use -c on a file which is of equal size as the one on the server, Wget will refuse to download the file and print an explanatory message. The same happens when the file is smaller on the server than locally (presumably because it was changed on the server since your last download attempt)—because “continuing” is not meaningful, no download occurs.
On the other side of the coin, while using -c, any file that's
bigger on the server than locally will be considered an incomplete
download and only (length(remote) - length(local)) bytes will be
downloaded and tacked onto the end of the local file. This behavior can
be desirable in certain cases—for instance, you can use wget -c
to download just the new portion that's been appended to a data
collection or log file.
However, if the file is bigger on the server because it's been changed, as opposed to just appended to, you'll end up with a garbled file. Wget has no way of verifying that the local file is really a valid prefix of the remote file. You need to be especially careful of this when using -c in conjunction with -r, since every file will be considered as an "incomplete download" candidate.
Another instance where you'll get a garbled file if you try to use -c is if you have a lame http proxy that inserts a “transfer interrupted” string into the local file. In the future a “rollback” option may be added to deal with this case.
Note that -c only works with ftp servers and with http
servers that support the Range header.
The “bar” indicator is used by default. It draws an ascii progress bar graphics (a.k.a “thermometer” display) indicating the status of retrieval. If the output is not a TTY, the “dot” bar will be used by default.
Use --progress=dot to switch to the “dot” display. It traces the retrieval by printing dots on the screen, each dot representing a fixed amount of downloaded data.
When using the dotted retrieval, you may also set the style by
specifying the type as dot:style. Different styles assign
different meaning to one dot. 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).
Note that you can set the default style using the progress
command in .wgetrc. That setting may be overridden from the
command line. The exception is that, when the output is not a TTY, the
“dot” progress will be favored over “bar”. To force the bar output,
use --progress=bar:force.
wget --spider --force-html -i bookmarks.html
This feature needs much more work for Wget to get close to the functionality of real web spiders.
When interacting with the network, Wget can check for timeout and abort the operation if it takes too long. This prevents anomalies like hanging reads and infinite connects. The only timeout enabled by default is a 900-second read timeout. Setting a timeout to 0 disables it altogether. Unless you know what you are doing, it is best not to change the default timeout settings.
All timeout-related options accept decimal values, as well as subsecond values. For example, 0.1 seconds is a legal (though unwise) choice of timeout. Subsecond timeouts are useful for checking server response times or for testing network latency.
Of course, the remote server may choose to terminate the connection sooner than this option requires. The default read timeout is 900 seconds.
This option allows the use of decimal numbers, usually in conjunction with power suffixes; for example, --limit-rate=2.5k is a legal value.
Note that Wget implements the limiting by sleeping the appropriate amount of time after a network read that took less time than specified by the rate. Eventually this strategy causes the TCP transfer to slow down to approximately the specified rate. However, it may take some time for this balance to be achieved, so don't be surprised if limiting the rate doesn't work well with very small files.
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.
Note that this option is turned on by default in the global wgetrc file.
A recent article in a publication devoted to development on a popular consumer platform provided code to perform this analysis on the fly. Its author suggested blocking at the class C address level to ensure automated retrieval programs were blocked despite changing DHCP-supplied addresses.
The --random-wait option was inspired by this ill-advised recommendation to block many unrelated users from a web site due to the actions of one.
*_proxy environment
variable is defined.
For more information about the use of proxies with Wget, See Proxies.
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.
However, it has been reported that in some situations it is not
desirable to cache host names, even for the duration of a
short-running application like Wget. With this option Wget issues a
new DNS lookup (more precisely, a new call to gethostbyname or
getaddrinfo) each time it makes a new connection. Please note
that this option will not affect caching that might be
performed by the resolving library or by an external caching layer,
such as NSCD.
If you don't understand exactly what this option does, you probably won't need it.
By default, Wget escapes the characters that are not valid as part of file names on your operating system, as well as control characters that are typically unprintable. This option is useful for changing these defaults, either because you are downloading to a non-native partition, or because you want to disable escaping of the control characters.
When mode is set to “unix”, Wget escapes the character / and the control characters in the ranges 0–31 and 128–159. This is the default on Unix-like OS'es.
When mode is set to “windows”, Wget escapes the characters \, |, /, :, ?, ", *, <, >, and the control characters in the ranges 0–31 and 128–159. In addition to this, Wget in Windows mode uses + instead of : to separate host and port in local file names, and uses @ instead of ? to separate the query portion of the file name from the rest. Therefore, a URL that would be saved as www.xemacs.org:4300/search.pl?input=blah in Unix mode would be saved as www.xemacs.org+4300/search.pl@input=blah in Windows mode. This mode is the default on Windows.
If you append ,nocontrol to the mode, as in unix,nocontrol, escaping of the control characters is also switched off. You can use --restrict-file-names=nocontrol to turn off escaping of control characters without affecting the choice of the OS to use as file name restriction mode.
Neither options should be needed normally. By default, an IPv6-aware Wget will use the address family specified by the host's DNS record. If the DNS specifies both an A record and an AAAA record, Wget will try them in sequence until it finds one it can connect to.
These options can be used to deliberately force the use of IPv4 or
IPv6 address families on dual family systems, usually to aid debugging
or to deal with broken network configuration. Only one of
--inet6-only and --inet4-only may be specified in the
same command. Neither option is available in Wget compiled without
IPv6 support.
This avoids spurious errors and connect attempts when accessing hosts
that resolve to both IPv6 and IPv4 addresses from IPv4 networks. For
example, www.kame.net resolves to
2001:200:0:8002:203:47ff:fea5:3085 and to
203.178.141.194. When the preferred family is IPv4, the
IPv4 address is used first; when the preferred family is IPv6,
the IPv6 address is used first; if the specified value is none,
the address order returned by DNS is used without change.
Unlike -4 and -6, this option doesn't inhibit access to
any address family, it only changes the order in which the
addresses are accessed. Also note that the reordering performed by
this option is stable—it doesn't affect order of addresses of
the same family. That is, the relative order of all IPv4 addresses
and of all IPv6 addresses remains intact in all cases.
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.
Note that filenames changed in this way will be re-downloaded every time you re-mirror a site, because Wget can't tell that the local X.html file corresponds to remote URL X (since it doesn't yet know that the URL produces output of type text/html or application/xhtml+xml. To prevent this re-downloading, you must use -k and -K so that the original version of the file will be saved as X.orig (see Recursive Retrieval Options).
basic (insecure) or the
digest authentication scheme.
Another way to specify username and password is in the url itself
(see URL Format). Either method reveals your password to anyone who
bothers to run ps. To prevent the passwords from being seen,
store them in .wgetrc or .netrc, and make sure to protect
those files from other users with chmod. If the passwords are
really important, do not leave them lying in those files either—edit
the files and delete them after Wget has started the download.
Caching is allowed by default.
Set-Cookie header, and the client responds with the same cookie
upon further requests. Since cookies allow the server owners to keep
track of visitors and for sites to exchange this information, some
consider them a breach of privacy. The default is to use cookies;
however, storing cookies is not on by default.
You will typically use this option when mirroring sites that require that you be logged in to access some or all of their content. The login process typically works by the web server issuing an http cookie upon receiving and verifying your credentials. The cookie is then resent by the browser when accessing that part of the site, and so proves your identity.
Mirroring such a site requires Wget to send the same cookies your browser sends when communicating with the site. This is achieved by --load-cookies—simply point Wget to the location of the cookies.txt file, and it will send the same cookies your browser would send in the same situation. Different browsers keep textual cookie files in different locations:
If you cannot use --load-cookies, there might still be an alternative. If your browser supports a “cookie manager”, you can use it to view the cookies used when accessing the site you're mirroring. Write down the name and value of the cookie, and manually instruct Wget to send those cookies, bypassing the “official” cookie support:
wget --no-cookies --header "Cookie: name=value"
Since the cookie file format does not normally carry session cookies, Wget marks them with an expiry timestamp of 0. Wget's --load-cookies recognizes those as session cookies, but it might confuse other browsers. Also note that cookies so loaded will be treated as other session cookies, which means that if you want --save-cookies to preserve them again, you must use --keep-session-cookies again.
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.
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.srk.fer.hr/
Specification of an empty string as the header value will clear all previous user-defined headers.
As of Wget 1.10, this option can be used to override headers otherwise
generated automatically. This example instructs Wget to connect to
localhost, but to specify foo.bar in the Host header:
wget --header="Host: foo.bar" http://localhost/
In versions of Wget prior to 1.10 such use of --header caused sending of duplicate headers.
basic authentication scheme.
Security considerations similar to those with --http-password pertain here as well.
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 this is not such a bad idea in theory, it has been abused by
servers denying information to clients other than (historically)
Netscape or, more frequently, 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.
Specifying empty user agent with --user-agent="" instructs Wget
not to send the User-Agent header in http requests.
--post-data sends string as data,
whereas --post-file sends the contents of file. Other than
that, they work in exactly the same way.
Please be aware that Wget needs to know the size of the POST data in
advance. Therefore the argument to --post-file must be a regular
file; specifying a FIFO or something like /dev/stdin won't work.
It's not quite clear how to work around this limitation inherent in
HTTP/1.0. Although HTTP/1.1 introduces chunked transfer that
doesn't require knowing the request length in advance, a client can't
use chunked unless it knows it's talking to an HTTP/1.1 server. And it
can't know that until it receives a response, which in turn requires the
request to have been completed – a chicken-and-egg problem.
Note: if Wget is redirected after the POST request is completed, it will not send the POST data to the redirected URL. This is because URLs that process POST often respond with a redirection to a regular page, which does not desire or accept POST. It is not completely clear that this behavior is optimal; if it doesn't work out, it might be changed in the future.
This example shows how to log to a server using POST and then proceed to download the desired pages, presumably only accessible to authorized users:
# Log in to the server. This can be done only once. wget --save-cookies cookies.txt \ --post-data 'user=foo&password=bar' \ http://server.com/auth.php # Now grab the page or pages we care about. wget --load-cookies cookies.txt \ -p http://server.com/interesting/article.php
If the server is using session cookies to track user authentication, the above will not work because --save-cookies will not save them (and neither will browsers) and the cookies.txt file will be empty. In that case use --keep-session-cookies along with --save-cookies to force saving of session cookies.
To support encrypted HTTP (HTTPS) downloads, Wget must be compiled with an external SSL library, currently OpenSSL. If Wget is compiled without SSL support, none of these options are available.
Specifying SSLv2, SSLv3, or TLSv1 forces the use of the corresponding protocol. This is useful when talking to old and buggy SSL server implementations that make it hard for OpenSSL to choose the correct protocol version. Fortunately, such servers are quite rare.
As of Wget 1.10, the default is to verify the server's certificate against the recognized certificate authorities, breaking the SSL handshake and aborting the download if the verification fails. Although this provides more secure downloads, it does break interoperability with some sites that worked with previous Wget versions, particularly those using self-signed, expired, or otherwise invalid certificates. This option forces an “insecure” mode of operation that turns the certificate verification errors into warnings and allows you to proceed.
If you encounter “certificate verification” errors or ones saying that “common name doesn't match requested host name”, you can use this option to bypass the verification and proceed with the download. Only use this option if you are otherwise convinced of the site's authenticity, or if you really don't care about the validity of its certificate. It is almost always a bad idea not to check the certificates when transmitting confidential or important data.
Without this option Wget looks for CA certificates at the system-specified locations, chosen at OpenSSL installation time.
c_rehash utility supplied with
OpenSSL. Using --ca-directory is more efficient than
--ca-certificate when many certificates are installed because
it allows Wget to fetch certificates on demand.
Without this option Wget looks for CA certificates at the system-specified locations, chosen at OpenSSL installation time.
On such systems the SSL library needs an external source of randomness
to initialize. Randomness may be provided by EGD (see
--egd-file below) or read from an external source specified by
the user. If this option is not specified, Wget looks for random data
in $RANDFILE or, if that is unset, in $HOME/.rnd. If
none of those are available, it is likely that SSL encryption will not
be usable.
If you're getting the “Could not seed OpenSSL PRNG; disabling SSL.” error, you should provide random data using some of the methods described above.
OpenSSL allows the user to specify his own source of entropy using the
RAND_FILE environment variable. If this variable is unset, or
if the specified file does not produce enough randomness, OpenSSL will
read random data from EGD socket specified using this option.
If this option is not specified (and the equivalent startup command is not used), EGD is never contacted. EGD is not needed on modern Unix systems that support /dev/random.
Another way to specify username and password is in the url itself
(see URL Format). Either method reveals your password to anyone who
bothers to run ps. To prevent the passwords from being seen,
store them in .wgetrc or .netrc, and make sure to protect
those files from other users with chmod. If the passwords are
really important, do not leave them lying in those files either—edit
the files and delete them after Wget has started the download.
Note that even though Wget writes to a known filename for this file,
this is not a security hole in the scenario of a user making
.listing a symbolic link to /etc/passwd or something and
asking root to run Wget in his or her directory. Depending on
the options used, either Wget will refuse to write to .listing,
making the globbing/recursion/time-stamping operation fail, or the
symbolic link will be deleted and replaced with the actual
.listing file, or the listing will be written to a
.listing.number file.
Even though this situation isn't a problem, though, root should
never run Wget in a non-trusted user's directory. A user could do
something as simple as linking index.html to /etc/passwd
and asking root to run Wget with -N or -r so the file
will be overwritten.
wget ftp://gnjilux.srk.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).
If the machine is connected to the Internet directly, both passive and
active FTP should work equally well. Behind most firewall and NAT
configurations passive FTP has a better chance of working. However,
in some rare firewall configurations, active FTP actually works when
passive FTP doesn't. If you suspect this to be the case, use this
option, or set passive_ftp=off in your init file.
When --retr-symlinks is specified, however, symbolic links are traversed and the pointed-to files are retrieved. At this time, this option does not cause Wget to traverse symlinks to directories and recurse through them, but in the future it should be enhanced to do this.
Note that when retrieving a file (not a directory) because it was specified on the command-line, rather than because it was recursed to, this option has no effect. Symbolic links are always traversed in this case.
This option is useful when, for some reason, persistent (keep-alive) connections don't work for you, for example due to a server bug or due to the inability of server-side scripts to cope with the connections.
wget -r -nd --delete-after http://whatever.com/~popular/page/
The -r option is to retrieve recursively, and -nd to not create directories.
Note that --delete-after deletes files on the local machine. It does not issue the DELE command to remote FTP sites, for instance. Also note that when --delete-after is specified, --convert-links is ignored, so .orig files are simply not created in the first place.
Each link will be changed in one of the two ways:
Example: if the downloaded file /foo/doc.html links to /bar/img.gif, also downloaded, then the link in doc.html will be modified to point to ../bar/img.gif. This kind of transformation works reliably for arbitrary combinations of directories.
Example: if the downloaded file /foo/doc.html links to /bar/img.gif (or to ../bar/img.gif), then the link in doc.html will be modified to point to http://hostname/bar/img.gif.
Because of this, local browsing works reliably: if a linked file was downloaded, the link will refer to its local name; if it was not downloaded, the link will refer to its full Internet address rather than presenting a broken link. The fact that the former links are converted to relative links ensures that you can move the downloaded hierarchy to another directory.
Note that only at the end of the download can Wget know which links have been downloaded. Because of that, the work done by -k will be performed at the end of all the downloads.
Ordinarily, when downloading a single html page, any requisite documents that may be needed to display it properly are not downloaded. Using -r together with -l can help, but since Wget does not ordinarily distinguish between external and inlined documents, one is generally left with “leaf documents” that are missing their requisites.
For instance, say document 1.html contains an <IMG> tag
referencing 1.gif and an <A> tag pointing to external
document 2.html. Say that 2.html is similar but that its
image is 2.gif and it links to 3.html. Say this
continues up to some arbitrarily high number.
If one executes the command:
wget -r -l 2 http://site/1.html
then 1.html, 1.gif, 2.html, 2.gif, and 3.html will be downloaded. As you can see, 3.html is without its requisite 3.gif because Wget is simply counting the number of hops (up to 2) away from 1.html in order to determine where to stop the recursion. However, with this command:
wget -r -l 2 -p http://site/1.html
all the above files and 3.html's requisite 3.gif will be downloaded. Similarly,
wget -r -l 1 -p http://site/1.html
will cause 1.html, 1.gif, 2.html, and 2.gif to be downloaded. One might think that:
wget -r -l 0 -p http://site/1.html
would download just 1.html and 1.gif, but unfortunately this is not the case, because -l 0 is equivalent to -l inf—that is, infinite recursion. To download a single html page (or a handful of them, all specified on the command-line or in a -i url input file) and its (or their) requisites, simply leave off -r and -l:
wget -p http://site/1.html
Note that Wget will behave as if -r had been specified, but only that single page and its requisites will be downloaded. Links from that page to external documents will not be followed. Actually, to download a single page and all its requisites (even if they exist on separate websites), and make sure the lot displays properly locally, this author likes to use a few options in addition to -p:
wget -E -H -k -K -p http://site/document
To finish off this topic, it's worth knowing that Wget's idea of an
external document link is any URL specified in an <A> tag, an
<AREA> tag, or a <LINK> tag other than <LINK
REL="stylesheet">.
According to specifications, html comments are expressed as sgml declarations. Declaration is special markup that begins with <! and ends with >, such as <!DOCTYPE ...>, that may contain comments between a pair of -- delimiters. html comments are “empty declarations”, sgml declarations without any non-comment text. Therefore, <!--foo--> is a valid comment, and so is <!--one-- --two-->, but <!--1--2--> is not.
On the other hand, most html writers don't perceive comments as anything other than text delimited with <!-- and -->, which is not quite the same. For example, something like <!------------> works as a valid comment as long as the number of dashes is a multiple of four (!). If not, the comment technically lasts until the next --, which may be at the other end of the document. Because of this, many popular browsers completely ignore the specification and implement what users have come to expect: comments delimited with <!-- and -->.
Until version 1.9, Wget interpreted comments strictly, which resulted in missing links in many web pages that displayed fine in browsers, but had the misfortune of containing non-compliant comments. Beginning with version 1.9, Wget has joined the ranks of clients that implements “naive” comments, terminating each comment at the first occurrence of -->.
If, for whatever reason, you want strict comment parsing, use this option to turn it on.
In the past, this option was the best bet for downloading a single page and its requisites, using a command-line like:
wget --ignore-tags=a,area -H -k -K -r http://site/document
However, the author of this option came across a page with tags like
<LINK REL="home" HREF="/"> and came to the realization that
specifying tags to ignore was not enough. One can't just tell Wget to
ignore <LINK>, because then stylesheets will not be downloaded.
Now the best bet for downloading a single page and its requisites is the
dedicated --page-requisites option.
GNU Wget is capable of traversing parts of the Web (or a single http or ftp server), following links and directory structure. We refer to this as to recursive retrieval, 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 markup like href, or
src. If the freshly downloaded file is also of type
text/html or application/xhtml+xml, it will be parsed and
followed further.
Recursive retrieval of http and html content is breadth-first. This means that Wget first downloads the requested html document, then the documents linked from that document, then the documents linked by them, and so on. In other words, Wget first downloads the documents at depth 1, then those at depth 2, and so on until the specified maximum depth.
The maximum depth to which the retrieval may descend is specified with the -l option. The default maximum depth is five layers.
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. Unlike http recursion, ftp recursion is performed
depth-first.
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 recursive downloads can overload the remote servers. Because of that, many administrators frown upon them and may ban access from your site if they detect very fast downloads of big amounts of content. When downloading from Internet servers, consider using the -w option to introduce a delay between accesses to the server. The download will take a while longer, but the server administrator will not be alarmed by your rudeness.
Of course, recursive download may cause problems on your machine. If left to run unchecked, it can easily fill up the disk. If downloading from local network, it can also take bandwidth on the system, as well as consume memory and CPU.
Try to specify the criteria that match the kind of download you are trying to achieve. If you want to download only one page, use --page-requisites without any additional recursion. If you want to download things under one directory, use -np to avoid downloading things from other directories. If you want to download all the files from one directory, use -l 1 to make sure the recursion depth never exceeds one. See Following Links, for more information about this.
Recursive retrieval should be used with care. Don't say you were not warned.
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.srk.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.
Wget's recursive retrieval normally refuses to visit hosts different than the one you specified on the command line. This is a reasonable default; without it, every retrieval would have the potential to turn your Wget into a small version of google.
However, visiting different hosts, or host spanning, is sometimes a useful option. Maybe the images are served from a different server. Maybe you're mirroring a site that consists of pages interlinked between three servers. Maybe the server has two equivalent names, and the html pages refer to both interchangeably.
wget -rH -Dserver.com http://www.server.com/
You can specify more than one address by separating them with a comma,
e.g. -Ddomain1.com,domain2.com.
wget -rH -Dfoo.edu --exclude-domains sunsite.foo.edu \
http://www.foo.edu/
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.
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.
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.
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.
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/
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.
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.
When -L is turned on, only the relative links are ever followed. Relative links are here defined those that do not refer to the web server root. For example, these links are relative:
<a href="foo.gif">
<a href="foo/bar.gif">
<a href="../foo/bar.gif">
These links are not relative:
<a href="/foo.gif">
<a href="/foo/bar.gif">
<a href="http://www.server.com/foo/bar.gif">
Using this option guarantees that recursive retrieval will not span hosts, even without -H. In simple cases it also allows downloads to “just work” without having to convert links.
This option is probably not very useful and might be removed in a future release.
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.
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:
To implement this, the program needs to be aware of the time of last modification of both local and remote files. We call this information the time-stamp of a file.
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.
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 (at least for http).
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 has the same timestamp as the server, or a newer one, the remote file will not be re-fetched. However, if the remote file is more recent, Wget will proceed to fetch it.
The same goes for ftp. For example:
wget "ftp://ftp.ifi.uio.no/pub/emacs/gnus/*"
(The quotes around that URL are to prevent the shell from trying to interpret the *.)
After download, a local directory listing will show that the timestamps match those on the remote server. Reissuing the command with -N will make Wget re-fetch only the files that have been modified since the last download.
If you wished to mirror the GNU archive every week, you would use a command like the following, weekly:
wget --timestamping -r ftp://ftp.gnu.org/pub/gnu/
Note that time-stamping will only work for files for which the server
gives a timestamp. For http, this depends on getting a
Last-Modified header. For ftp, this depends on getting a
directory listing with dates in a format that Wget can parse
(see FTP 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.2
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.
In theory, ftp time-stamping works much the same as http, only ftp has no headers—time-stamps must be ferreted out of directory listings.
If an ftp download is recursive or uses globbing, Wget will use the
ftp LIST command to get a file listing for the directory
containing the desired file(s). It will try to analyze the listing,
treating it like Unix ls -l output, extracting the time-stamps.
The rest is exactly the same as for http. Note that when
retrieving individual files from an ftp server without using
globbing or recursion, listing files will not be downloaded (and thus
files will not be time-stamped) unless -N is specified.
Assumption that every directory listing is a Unix-style listing may sound extremely constraining, but in practice it is not, as many non-Unix ftp servers use the Unixoid listing format because most (all?) of the clients understand it. Bear in mind that rfc959 defines no standard way to get a file list, let alone the time-stamps. We can only hope that a future standard will define this.
Another non-standard solution includes the use of MDTM command
that is supported by some ftp servers (including the popular
wu-ftpd), which returns the exact time of the specified file.
Wget may support this command in the future.
Once you know how to change default settings of Wget through command line arguments, you may wish to make some of those settings permanent. You can do that in a convenient way by creating the Wget startup file—.wgetrc.
Besides .wgetrc is the “main” initialization file, it is convenient to have a special facility for storing passwords. Thus Wget reads and interprets the contents of $HOME/.netrc, if it finds it. You can find .netrc format in your system manuals.
Wget reads .wgetrc upon startup, recognizing a limited set of commands.
When initializing, Wget will look for a global startup file, /usr/local/etc/wgetrc by default (or some prefix other than /usr/local, if Wget was not installed there) and read commands from there, if it exists.
Then it will look for the user's file. If the environmental variable
WGETRC is set, Wget will try to load that file. Failing that, no
further attempts will be made.
If WGETRC is not set, Wget will try to load $HOME/.wgetrc.
The fact that user's settings are loaded after the system-wide ones means that in case of collision user's wgetrc overrides the system-wide wgetrc (in /usr/local/etc/wgetrc by default). Fascist admins, away!
The syntax of a wgetrc command is simple:
variable = value
The variable will also be called command. Valid values are different for different commands.
The commands are case-insensitive and underscore-insensitive. Thus DIr__PrefiX is the same as dirprefix. Empty lines, lines beginning with # and lines containing white-space only are discarded.
Commands that expect a comma-separated list will clear the list on an empty command. So, if you wish to reset the rejection list specified in global wgetrc, you can do it with:
reject =
The complete set of commands is listed below. Legal values are listed after the =. Simple Boolean values can be set or unset using on and off or 1 and 0. A fancier kind of Boolean allowed in some cases is the lockable Boolean, which may be set to on, off, always, or never. If an option is set to always or never, that value will be locked in for the duration of the Wget invocation—command-line options will not override.
Some commands take pseudo-arbitrary values. address values can be hostnames or dotted-quad IP addresses. n can be any positive integer, or inf for infinity, where appropriate. string values can be any non-empty string.
Most of these commands have direct command-line equivalents. Also, any wgetrc command can be specified on the command line using the --execute switch (see Basic Startup Options.)
This command used to be named passwd prior to Wget 1.10.
This command used to be named login prior to Wget 1.10.
Content-Length header; the same as
--ignore-length.
Content-Length.
This is the sample initialization file, as given in the distribution. It is divided in two section—one for global usage (suitable for global startup file), and one for local usage (suitable for $HOME/.wgetrc). Be careful about the things you change.
Note that almost all the lines are commented out. For a command to have any effect, you must remove the # character at the beginning of its line.
###
### Sample Wget initialization file .wgetrc
###
## You can use this file to change the default behaviour of wget or to
## avoid having to type many many command-line options. This file does
## not contain a comprehensive list of commands -- look at the manual
## to find out what you can put into this file.
##
## Wget initialization file can reside in /usr/local/etc/wgetrc
## (global, for all users) or $HOME/.wgetrc (for a single user).
##
## To use the settings in this file, you will have to uncomment them,
## as well as change them, in most cases, as the values on the
## commented-out lines are the default values (e.g. "off").
##
## Global settings (useful for setting up in /usr/local/etc/wgetrc).
## Think well before you change them, since they may reduce wget's
## functionality, and make it behave contrary to the documentation:
##
# You can set retrieve quota for beginners by specifying a value
# optionally followed by 'K' (kilobytes) or 'M' (megabytes). The
# default quota is unlimited.
#quota = inf
# You can lower (or raise) the default number of retries when
# downloading a file (default is 20).
#tries = 20
# Lowering the maximum depth of the recursive retrieval is handy to
# prevent newbies from going too "deep" when they unwittingly start
# the recursive retrieval. The default is 5.
#reclevel = 5
# Many sites are behind firewalls that do not allow initiation of
# connections from the outside. On these sites you have to use the
# `passive' feature of FTP. If you are behind such a firewall, you
# can turn this on to make Wget use passive FTP by default.
#passive_ftp = off
# The "wait" command below makes Wget wait between every connection.
# If, instead, you want Wget to wait only between retries of failed
# downloads, set waitretry to maximum number of seconds to wait (Wget
# will use "linear backoff", waiting 1 second after the first failure
# on a file, 2 seconds after the second failure, etc. up to this max).
waitretry = 10
##
## Local settings (for a user to set in his $HOME/.wgetrc). It is
## *highly* undesirable to put these settings in the global file, since
## they are potentially dangerous to "normal" users.
##
## Even when setting up your own ~/.wgetrc, you should know what you
## are doing before doing so.
##
# Set this to on to use timestamping by default:
#timestamping = off
# It is a good idea to make Wget send your email address in a `From:'
# header with your request (so that server administrators can contact
# you in case of errors). Wget does *not* send `From:' by default.
#header = From: Your Name <username@site.domain>
# You can set up other headers, like Accept-Language. Accept-Language
# is *not* sent by default.
#header = Accept-Language: en
# You can set the default proxies for Wget to use for http and ftp.
# They will override the value in the environment.
#http_proxy = http://proxy.yoyodyne.com:18023/
#ftp_proxy = http://proxy.yoyodyne.com:18023/
# If you do not want to use proxy at all, set this to off.
#use_proxy = on
# You can customize the retrieval outlook. Valid options are default,
# binary, mega and micro.
#dot_style = default
# Setting this to off makes Wget not download /robots.txt. Be sure to
# know *exactly* what /robots.txt is and how it is used before changing
# the default!
#robots = on
# It can be useful to make Wget wait between connections. Set this to
# the number of seconds you want Wget to wait.
#wait = 0
# You can force creating directory structure, even if a single is being
# retrieved, by setting this to on.
#dirstruct = off
# You can turn on recursive retrieving by default (don't do this if
# you are not sure you know what it means) by setting this to on.
#recursive = off
# To always back up file X as X.orig before converting its links (due
# to -k / --convert-links / convert_links = on having been specified),
# set this variable to on:
#backup_converted = off
# To have Wget follow FTP links from HTML files by default, set this
# to on:
#follow_ftp = off
The examples are divided into three sections loosely based on their complexity.
wget http://fly.srk.fer.hr/
wget --tries=45 http://fly.srk.fer.hr/jpg/flyweb.jpg
wget -t 45 -o log http://fly.srk.fer.hr/jpg/flyweb.jpg &
The ampersand at the end of the line makes sure that Wget works in the background. To unlimit the number of retries, use -t inf.
wget ftp://gnjilux.srk.fer.hr/welcome.msg
wget ftp://ftp.gnu.org/pub/gnu/
links index.html
wget -i file
If you specify - as file name, the urls will be read from standard input.
wget -r http://www.gnu.org/ -o gnulog
wget --convert-links -r http://www.gnu.org/ -o gnulog
wget -p --convert-links http://www.server.com/dir/page.html
The html page will be saved to www.server.com/dir/page.html, and the images, stylesheets, etc., somewhere under www.server.com/, depending on where they were on the remote server.
wget -p --convert-links -nH -nd -Pdownload \
http://www.server.com/dir/page.html
wget -S http://www.lycos.com/
wget --save-headers http://www.lycos.com/
more index.html
wget -r -l2 -P/tmp ftp://wuarchive.wustl.edu/
wget -r -l1 --no-parent -A.gif http://www.server.com/dir/
More verbose, but the effect is the same. -r -l1 means to retrieve recursively (see Recursive Download), with maximum depth of 1. --no-parent means that references to the parent directory are ignored (see Directory-Based Limits), and -A.gif means to download only the gif files. -A "*.gif" would have worked too.
wget -nc -r http://www.gnu.org/
wget ftp://hniksic:mypassword@unix.server.com/.emacs
Note, however, that this usage is not advisable on multi-user systems
because it reveals your password to anyone who looks at the output of
ps.
wget -O - http://jagor.srce.hr/ http://www.srce.hr/
You can also combine the two options and make pipelines to retrieve the documents from remote hotlists:
wget -O - http://cool.list.com/ | wget --force-html -i -
crontab
0 0 * * 0 wget --mirror http://www.gnu.org/ -o /home/me/weeklog
wget --mirror --convert-links --backup-converted \
http://www.gnu.org/ -o /home/me/weeklog
wget --mirror --convert-links --backup-converted \
--html-extension -o /home/me/weeklog \
http://www.gnu.org/
Or, with less typing:
wget -m -k -K -E http://www.gnu.org/ -o /home/me/weeklog
This chapter contains all the stuff that could not fit anywhere else.
Proxies are special-purpose http servers designed to transfer data from remote servers to local clients. One typical use of proxies is lightening network load for users behind a slow connection. This is achieved by channeling all http and ftp requests through the proxy which caches the transferred data. When a cached resource is requested again, proxy will return the data from cache. Another use for proxies is for companies that separate (for security reasons) their internal networks from the rest of Internet. In order to obtain information from the Web, their users connect and retrieve remote data using an authorized proxy.
Wget supports proxies for both http and ftp retrievals. The standard way to specify proxy location, which Wget recognizes, is using the following environment variables:
http_proxyftp_proxyno_proxyno_proxy is .mit.edu, proxy will not be used to retrieve
documents from MIT.
In addition to the environment variables, proxy location and settings may be specified from within Wget itself.
Some proxy servers require authorization to enable you to use them. The
authorization consists of username and password, which must
be sent by Wget. As with http authorization, several
authentication schemes exist. For proxy authorization only the
Basic authentication scheme is currently implemented.
You may specify your username and password either through the proxy url or through the command-line options. Assuming that the company's proxy is located at proxy.company.com at port 8001, a proxy url location containing authorization data might look like this:
http://hniksic:mypassword@proxy.company.com:8001/
Alternatively, you may use the proxy-user and
proxy-password options, and the equivalent .wgetrc
settings proxy_user and proxy_password to set the proxy
username and password.
Like all GNU utilities, the latest version of Wget can be found at the master GNU archive site ftp.gnu.org, and its mirrors. For example, Wget 1.10 can be found at ftp://ftp.gnu.org/pub/gnu/wget/wget-1.10.tar.gz
There are several Wget-related mailing lists, all hosted by SunSITE.dk. The general discussion list is at wget@sunsite.dk. It is the preferred place for bug reports and suggestions, as well as for discussion of development. You are invited to subscribe.
To subscribe, simply send mail to wget-subscribe@sunsite.dk and follow the instructions. Unsubscribe by mailing to wget-unsubscribe@sunsite.dk. The mailing list is archived at http://www.mail-archive.com/wget%40sunsite.dk/ and at http://news.gmane.org/gmane.comp.web.wget.general.
The second mailing list is at wget-patches@sunsite.dk, and is used to submit patches for review by Wget developers. A “patch” is a textual representation of change to source code, readable by both humans and programs. The file PATCHES that comes with Wget covers the creation and submitting of patches in detail. Please don't send general suggestions or bug reports to wget-patches; use it only for patch submissions.
To subscribe, simply send mail to wget-subscribe@sunsite.dk and follow the instructions. Unsubscribe by mailing to wget-unsubscribe@sunsite.dk. The mailing list is archived at http://news.gmane.org/gmane.comp.web.wget.patches.
Finally, there is a read-only list at wget-cvs@sunsite.dk that tracks commits to the Wget CVS repository. To subscribe to that list, send mail to wget-cvs-subscribe@sunsite.dk. The list is not archived.
You are welcome to send bug reports about GNU Wget to bug-wget@gnu.org.
Before actually submitting a bug report, please try to follow a few simple guidelines.
Also, while I will probably be interested to know the contents of your .wgetrc file, just dumping it into the debug message is probably a bad idea. Instead, you should first try to see if the bug repeats with .wgetrc moved out of the way. Only if it turns out that .wgetrc settings affect the bug, mail me the relevant parts of the file.
Note: please make sure to remove any potentially sensitive information
from the debug log before sending it to the bug address. The
-d won't go out of its way to collect sensitive information,
but the log will contain a fairly complete transcript of Wget's
communication with the server, which may include passwords and pieces
of downloaded data. Since the bug address is publically archived, you
may assume that all bug reports are visible to the public.
gdb `which
wget` core and type where to get the backtrace. This may not
work if the system administrator has disabled core files, but it is
safe to try.
Like all GNU software, Wget works on the GNU system. However, since it uses GNU Autoconf for building and configuring, and mostly avoids using “special” features of any particular Unix, it should compile (and work) on all common Unix flavors.
Various Wget versions have been compiled and tested under many kinds of Unix systems, including GNU/Linux, Solaris, SunOS 4.x, OSF (aka Digital Unix or Tru64), Ultrix, *BSD, IRIX, AIX, and others. Some of those systems are no longer in widespread use and may not be able to support recent versions of Wget. If Wget fails to compile on your system, we would like to know about it.
Thanks to kind contributors, this version of Wget compiles and works on 32-bit Microsoft Windows platforms. It has been compiled successfully using MS Visual C++ 6.0, Watcom, Borland C, and GCC compilers. Naturally, it is crippled of some features available on Unix, but it should work as a substitute for people stuck with Windows. Note that Windows-specific portions of Wget are not guaranteed to be supported in the future, although this has been the case in practice for many years now. All questions and problems in Windows usage should be reported to Wget mailing list at wget@sunsite.dk where the volunteers who maintain the Windows-related features might look at them.
Since the purpose of Wget is background work, it catches the hangup
signal (SIGHUP) and ignores it. If the output was on standard
output, it will be redirected to a file named wget-log.
Otherwise, SIGHUP is ignored. This is convenient when you wish
to redirect the output of Wget after having started it.
$ wget http://www.gnus.org/dist/gnus.tar.gz &
...
$ kill -HUP %%
SIGHUP received, redirecting output to `wget-log'.
Other than that, Wget will not try to interfere with signals in any way.
C-c, kill -TERM and kill -KILL should kill it alike.
This chapter contains some references I consider useful.
It is extremely easy to make Wget wander aimlessly around a web site, sucking all the available data in progress. wget -r site, and you're set. Great? Not for the server admin.
As long as Wget is only retrieving static pages, and doing it at a
reasonable rate (see the --wait option), there's not much of a
problem. The trouble is that Wget can't tell the difference between the
smallest static page and the most demanding CGI. A site I know has a
section handled by a CGI Perl script that converts Info files to html on
the fly. The script is slow, but works well enough for human users
viewing an occasional Info file. However, when someone's recursive Wget
download stumbles upon the index page that links to all the Info files
through the script, the system is brought to its knees without providing
anything useful to the user (This task of converting Info files could be
done locally and access to Info documentation for all installed GNU
software on a system is available from the info command).
To avoid this kind of accident, as well as to preserve privacy for documents that need to be protected from well-behaved robots, the concept of robot exclusion was invented. The idea is that the server administrators and document authors can specify which portions of the site they wish to protect from robots and those they will permit access.
The most popular mechanism, and the de facto standard supported by all the major robots, is the “Robots Exclusion Standard” (RES) written by Martijn Koster et al. in 1994. It specifies the format of a text file containing directives that instruct the robots which URL paths to avoid. To be found by the robots, the specifications must be placed in /robots.txt in the server root, which the robots are expected to download and parse.
Although Wget is not a web robot in the strictest sense of the word, it can downloads large parts of the site without the user's intervention to download an individual page. Because of that, Wget honors RES when downloading recursively. For instance, when you issue:
wget -r http://www.server.com/
First the index of www.server.com will be downloaded. If Wget finds that it wants to download more documents from that server, it will request http://www.server.com/robots.txt and, if found, use it for further downloads. robots.txt is loaded only once per each server.
Until version 1.8, Wget supported the first version of the standard, written by Martijn Koster in 1994 and available at http://www.robotstxt.org/wc/norobots.html. As of version 1.8, Wget has supported the additional directives specified in the internet draft <draft-koster-robots-00.txt> titled “A Method for Web Robots Control”. The draft, which has as far as I know never made to an rfc, is available at http://www.robotstxt.org/wc/norobots-rfc.txt.
This manual no longer includes the text of the Robot Exclusion Standard.
The second, less known mechanism, enables the author of an individual
document to specify whether they want the links from the file to be
followed by a robot. This is achieved using the META tag, like
this:
<meta name="robots" content="nofollow">
This is explained in some detail at http://www.robotstxt.org/wc/meta-user.html. Wget supports this method of robot exclusion in addition to the usual /robots.txt exclusion.
If you know what you are doing and really really wish to turn off the
robot exclusion, set the robots variable to off in your
.wgetrc. You can achieve the same effect from the command line
using the -e switch, e.g. wget -e robots=off url....
When using Wget, you must be aware that it sends unencrypted passwords through the network, which may present a security problem. Here are the main issues, and some solutions.
ps. The best
way around it is to use wget -i - and feed the urls to
Wget's standard input, each on a separate line, terminated by C-d.
Another workaround is to use .netrc to store passwords; however,
storing unencrypted passwords is also considered a security risk.
GNU Wget was written by Hrvoje Niksic hniksic@xemacs.org. However, its development could never have gone as far as it has, were it not for the help of many people, either with bug reports, feature proposals, patches, or letters saying “Thanks!”.
Special thanks goes to the following people (no particular order):
ansi2knr-ization. Lots of
portability fixes.
Digest
authentication.
The following people have provided patches, bug/build reports, useful suggestions, beta testing services, fan mail and all the other things that make maintenance so much fun:
Ian Abbott Tim Adam, Adrian Aichner, Martin Baehr, Dieter Baron, Roger Beeman, Dan Berger, T. Bharath, Christian Biere, Paul Bludov, Daniel Bodea, Mark Boyns, John Burden, Wanderlei Cavassin, Gilles Cedoc, Tim Charron, Noel Cragg, Kristijan Conkas, John Daily, Andreas Damm, Ahmon Dancy, Andrew Davison, Bertrand Demiddelaer, Andrew Deryabin, Ulrich Drepper, Marc Duponcheel, Damir Dzeko, Alan Eldridge, Hans-Andreas Engel, Aleksandar Erkalovic, Andy Eskilsson, Christian Fraenkel, David Fritz, Charles C. Fu, FUJISHIMA Satsuki, Masashi Fujita, Howard Gayle, Marcel Gerrits, Lemble Gregory, Hans Grobler, Mathieu Guillaume, Dan Harkless, Aaron Hawley, Herold Heiko, Jochen Hein, Karl Heuer, HIROSE Masaaki, Ulf Harnhammar, Gregor Hoffleit, Erik Magnus Hulthen, Richard Huveneers, Jonas Jensen, Larry Jones, Simon Josefsson, Mario Juric, Hack Kampbjorn, Const Kaplinsky, Goran Kezunovic, Igor Khristophorov, Robert Kleine, KOJIMA Haime, Fila Kolodny, Alexander Kourakos, Martin Kraemer, Sami Krank, Simos KSenitellis, Christian Lackas, Hrvoje Lacko, Daniel S. Lewart, Nicolas Lichtmeier, Dave Love, Alexander V. Lukyanov, Thomas Lussnig, Andre Majorel, Aurelien Marchand, Matthew J. Mellon, Jordan Mendelson, Lin Zhe Min, Jan Minar, Tim Mooney, Keith Moore, Adam D. Moss, Simon Munton, Charlie Negyesi, R. K. Owen, Leonid Petrov, Simone Piunno, Andrew Pollock, Steve Pothier, Jan Prikryl, Marin Purgar, Csaba Raduly, Keith Refson, Bill Richardson, Tyler Riddle, Tobias Ringstrom, Juan Jose Rodriguez, Maciej W. Rozycki, Edward J. Sabol, Heinz Salzmann, Robert Schmidt, Nicolas Schodet, Andreas Schwab, Chris Seawood, Dennis Smit, Toomas Soome, Tage Stabell-Kulo, Philip Stadermann, Daniel Stenberg, Sven Sternberger, Markus Strasser, John Summerfield, Szakacsits Szabolcs, Mike Thomas, Philipp Thomas, Mauro Tortonesi, Dave Turner, Gisle Vanem, Russell Vincent, Zeljko Vrba, Charles G Waldman, Douglas E. Wegscheid, YAMAZAKI Makoto, Jasmin Zainul, Bojan Zdrnja, Kristijan Zimmer.
Apologies to all who I accidentally left out, and many thanks to all the subscribers of the Wget mailing list.
GNU Wget is licensed under the GNU General Public License (GNU GPL), which makes it free software. Please note that “free” in “free software” refers to liberty, not price. As some people like to point out, it's the “free” of “free speech”, not the “free” of “free beer”.
The exact and legally binding distribution terms are spelled out below. The GPL guarantees that you have the right (freedom) to run and change GNU Wget and distribute it to others, and even—if you want—charge money for doing any of those things. With these rights comes the obligation to distribute the source code along with the software and to grant your recipients the same rights and impose the same restrictions.
This licensing model is also known as open source because it, among other things, makes sure that all recipients will receive the source code along with the program, and be able to improve it. The GNU project prefers the term “free software” for reasons outlined at http://www.gnu.org/philosophy/free-software-for-freedom.html.
The exact license terms are defined by this paragraph and the GNU General Public License it refers to:
GNU Wget is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.GNU Wget is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
A copy of the GNU General Public License is included as part of this manual; if you did not receive it, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
In addition to this, this manual is free in the same sense:
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with the Invariant Sections being “GNU General Public License” and “GNU Free Documentation License”, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”.
The full texts of the GNU General Public License and of the GNU Free Documentation License are available below.
Copyright © 1989, 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software—to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations.
Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and modification follow.
Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.
You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
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Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and “any later version”, you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.
If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the program's name and an idea of what it does.
Copyright (C) 20yy name of author
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) 20yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'. This is free software, and you are welcome
to redistribute it under certain conditions; type `show c'
for details.
The hypothetical commands show w and show c should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than show w and show c; they could even be mouse-clicks or menu items—whatever suits your program.
You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the program, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written
by James Hacker.
signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.
Copyright © 2000,2001,2002 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.
This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.
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