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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 section 6. Startup File), or specifying it on the command line.
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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
.
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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.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 section 6.2 Wgetrc Syntax).
wget -X '' -X /~nobody,/~somebody |
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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.
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bind()
to ADDRESS on
the local machine. ADDRESS may be specified as a hostname or IP
address. This option can be useful if your machine is bound to multiple
IPs.
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 section 5. 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 (yuck) `.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.
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.
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.
Please do not lower the default timeout value with this option unless you know what you are doing.
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.
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.
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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.
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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'. 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 section 2.9 Recursive Retrieval Options).
basic
(insecure) or the
digest
authentication scheme.
Another way to specify username and password is in the URL itself (see section 2.1 URL Format). For more information about security issues with Wget, See section 9.2 Security Considerations.
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.
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.
basic
authentication scheme.
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.
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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).
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 commandline, rather than because it was recursed to, this option has no effect. Symbolic links are always traversed in this case.
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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 commandline 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 -nh -p http://site/document |
In one case you'll need to add a couple more options. If document
is a <FRAMESET>
page, the "one more hop" that `-p' gives you
won't be enough--you'll get the <FRAME>
pages that are
referenced, but you won't get their requisites. Therefore, in
this case you'll need to add `-r -l1' to the commandline. The
`-r -l1' will recurse from the <FRAMESET>
page to to the
<FRAME>
pages, and the `-p' will get their requisites. If
you're already using a recursion level of 1 or more, you'll need to up
it by one. In the future, `-p' may be made smarter so that it'll
do "two more hops" in the case of a <FRAMESET>
page.
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">
.
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In the past, the `-G' option was the best bet for downloading a single page and its requisites, using a commandline like:
wget -Ga,area -H -k -K -nh -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
`-G' 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.
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