Types of Files (GNU Wget 1.21.1-dirty Manual)

4.2 Types of Files

When downloading material from the web, you will often want to restrict the retrieval to only certain file types. For example, if you are interested in downloading GIFs, you will not be overjoyed to get loads of PostScript documents, and vice versa.

Wget offers two options to deal with this problem. Each option description lists a short name, a long name, and the equivalent command in .wgetrc.

‘-A acclist’ ‘--accept acclist’ ‘accept = acclist’ ‘--accept-regex urlregex’ ‘accept-regex = urlregex’

The argument to ‘--accept’ option is a list of file suffixes or patterns that Wget will download during recursive retrieval. A suffix is the ending part of a file, and consists of “normal” letters, e.g. ‘gif’ or ‘.jpg’. A matching pattern contains shell-like wildcards, e.g. ‘books*’ or ‘zelazny*196[0-9]*’.

So, specifying ‘wget -A gif,jpg’ will make Wget download only the files ending with ‘gif’ or ‘jpg’, i.e. GIFs and JPEGs. On the other hand, ‘wget -A "zelazny*196[0-9]*"’ will download only files beginning with ‘zelazny’ and containing numbers from 1960 to 1969 anywhere within. Look up the manual of your shell for a description of how pattern matching works.

Of course, any number of suffixes and patterns can be combined into a comma-separated list, and given as an argument to ‘-A’.

The argument to ‘--accept-regex’ option is a regular expression which is matched against the complete URL.

‘-R rejlist’ ‘--reject rejlist’ ‘reject = rejlist’ ‘--reject-regex urlregex’ ‘reject-regex = urlregex’

The ‘--reject’ option works the same way as ‘--accept’, only its logic is the reverse; Wget will download all files except the ones matching the suffixes (or patterns) in the list.

So, if you want to download a whole page except for the cumbersome MPEGs and .AU files, you can use ‘wget -R mpg,mpeg,au’. Analogously, to download all files except the ones beginning with ‘bjork’, use ‘wget -R "bjork*"’. The quotes are to prevent expansion by the shell.

The argument to ‘--accept-regex’ option is a regular expression which is matched against the complete URL.

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 (as determined by a ‘.htm’ or ‘.html’ filename prefix). This behavior may not be desirable for all users, and may be changed for future versions of Wget.

Note, too, that query strings (strings at the end of a URL beginning with a question mark (‘?’) are not included as part of the filename for accept/reject rules, even though these will actually contribute to the name chosen for the local file. It is expected that a future version of Wget will provide an option to allow matching against query strings.

Finally, it’s worth noting that the accept/reject lists are matched twice against downloaded files: once against the URL’s filename portion, to determine if the file should be downloaded in the first place; then, after it has been accepted and successfully downloaded, the local file’s name is also checked against the accept/reject lists to see if it should be removed. The rationale was that, since ‘.htm’ and ‘.html’ files are always downloaded regardless of accept/reject rules, they should be removed after being downloaded and scanned for links, if they did match the accept/reject lists. However, this can lead to unexpected results, since the local filenames can differ from the original URL filenames in the following ways, all of which can change whether an accept/reject rule matches:

If the local file already exists and ‘--no-directories’ was specified, a numeric suffix will be appended to the original name.
If ‘--adjust-extension’ was specified, the local filename might have ‘.html’ appended to it. If Wget is invoked with ‘-E -A.php’, a filename such as ‘index.php’ will match be accepted, but upon download will be named ‘index.php.html’, which no longer matches, and so the file will be deleted.
Query strings do not contribute to URL matching, but are included in local filenames, and so do contribute to filename matching.

This behavior, too, is considered less-than-desirable, and may change in a future version of Wget.