NAME

       checklink - check the validity of links in an HTML or XHTML document

SYNOPSIS

       checklink  [ options ] uri ...

DESCRIPTION

       This manual page documents briefly the checklink command, a.k.a. the W3C® Link Checker.

       checklink is a program that reads an HTML or XHTML document, extracts a list of anchors and links and
       checks that no anchor is defined twice and that all the links are dereferenceable, including the
       fragments. It warns about HTTP redirects, including directory redirects, and can check recursively a part
       of a web site.

       The program can be used either as a command line tool or as a CGI script.

OPTIONS

       This program follow the usual GNU command line syntax, with long options starting with two dashes (`-').
       A summary of options is included below.

       -?, -h, --help
            Show summary of options.

       -V, --version
            Output version information.

       -s, --summary
            Show result summary only.

       -b, --broken
            Show only the broken links, not the redirects.

       -e, --directory
            Hide directory redirects - e.g. <http://www.w3.org/TR> -> <http://www.w3.org/TR/>.

       -r, --recursive
            Check the documents linked from the first one.

       -D, --depth n
            Check the documents linked from the first one to depth n (implies --recursive).

       -l, --location uri
            Scope of the documents checked (implies --recursive).  Can be specified multiple times in order to
            specify multiple recursion bases.  If the URI of a candidate document is downwards relative to any
            of the bases, it is considered to be within the scope.  If not specified, the default is the base
            URI of the initial document, for example for <http://www.w3.org/TR/html4/Overview.html> it would be
            <http://www.w3.org/TR/html4/>.

       -X, --exclude regexp
            Do not check links whose full, canonical URIs match regexp.  Note that this option limits recursion
            the same way as --exclude-docs with the same regular expression would.

       --exclude-docs regexp
            In recursive mode, do not check links in documents whose full, canonical URIs match regexp.  This
            option may be specified multiple times.

       --suppress-redirect URI->URI
            Do not report a redirect from the first to the second URI.  The "->" is literal text.  This option
            may be specified multiple times.  Whitespace may be used instead of "->" to separate the URIs.

       --suppress-redirect-prefix URI->URI
            Do not report a redirect from a child of the first URI to the same child of the second URI.  The
            \"->\" is literal text.  This option may be specified multiple times.  Whitespace may be used
            instead of "->" to separate the URIs.

       --suppress-temp-redirects
            Do not report warnings about temporary redirects.

       --suppress-broken CODE:URI
            Do not report a broken link with the given CODE.  CODE is the HTTP response, or -1 for robots
            exclusion.  The ":" is literal text.  This option may be specified multiple times.  Whitespace may
            be used instead of ":" to separate the CODE and the URI.

       --suppress-fragment URI
            Do not report the given broken fragment URI.  A fragment URI contains "#".  This option may be
            specified multiple times.

       -L, --languages accept-language
            The "Accept-Language" HTTP header to send.  In command line mode, this header is not sent by
            default.  The special value "auto" causes a value to be detected from the "LANG" environment
            variable, and sent if found.  In CGI mode, the default is to send the value received from the client
            as is.

       -c, --cookies cookie-file
            Use cookies, load/save them in cookie-file.  The special value "tmp" causes non-persistent use of
            cookies, i.e. they are used but only stored in memory for the duration of this link checker run.

       -R, --no-referer
            Do not send the "Referer" HTTP header.

       -q, --quiet
            No output if no errors are found.  Implies --summary.

       -v, --verbose
            Verbose mode.

       -i, --indicator
            Show progress while parsing as percentage of lines processed.  No indicator is shown for documents
            containing no linefeeds.

       -u, --user username
            Specify a username for authentication.

       -p, --password password
            Specify a password for authentication.

       --hide-same-realm
            Hide 401's that are in the same realm as the document checked.

       -S, --sleep secs
            Sleep the specified number of seconds between requests to each server.  Defaults to 1 second, which
            is also the minimum allowed.

       -t, --timeout secs
            Timeout for requests, in seconds.  The default is 30.

       -C, --connection-cache number
            Maximum number of cached connections.  Using this option overrides the "Connection_Cache_Size"
            configuration file parameter, see its documentation below for the default value and more
            information.

       -d, --domain domain
            Perl regular expression describing the domain to which the authentication information (if present)
            will be sent.  The default value can be specified in the configuration file.  See the "Trusted"
            entry in the configuration file description below for more information.

       --masquerade "real-prefix surrogate-prefix"
            Perform a simple string substitution: URIs which begin with the string "real-prefix" are rewritten
            using the "surrogate-prefix" before being dereferenced.  Useful for making a local directory
            masquerade as a remote one. For example:

              --masquerade "http://example.com/x/y/z/ file:///my/local/dir/"

            If the document being checked contains a link to http://example.com/x/y/z/foo.html, then the local
            file system will be checked for file:///my/local/dir/foo.html.

            --masquerade takes a single argument consisting of two URIs, separated by whitespace.  The quote
            marks are not part of the argument, but one usual way of providing a value with embedded whitespace
            is to enclose it in quotes.

       -H, --html
            HTML output.

FILES

       /etc/w3c/checklink.conf
            The main configuration file.  You can use the W3C_CHECKLINK_CFG environment variable to override the
            default location.

            "Trusted" specifies a regular expression for matching trusted domains (ie. domains where HTTP basic
            authentication, if any, will be sent).  The regular expression will be matched case insensitively
            against host names.  The default behavior (when unset, that is) is to send the authentication
            information only to the host which requests it; usually you don't want to change this.  For example,
            the following configures only the w3.org domain as trusted:

                Trusted = \.w3\.org$

            "Allow_Private_IPs" is a boolean flag indicating whether checking links on non-public IP addresses
            is allowed.  The default is true in command line mode and false when run as a CGI script.  For
            example, to disallow checking non-public IP addresses, regardless of the mode, use:

               Allow_Private_IPs = 0

            "Forbidden_Protocols" is a comma separated list of additional protocols/URI schemes that the link
            checker is not allowed to use.  The "javascript" and "mailto" schemes are always forbidden, and so
            is the "file" scheme when running as a CGI script.

               Forbidden_Protocols = javascript,mailto

            "Markup_Validator_URI" and "CSS_Validator_URI" are formatted URIs to the respective validators.  The
            %s in these will be replaced with the full "URI encoded" URI to the document being checked, and
            shown in the link checker results view in the online/CGI version.  The defaults are:

               Markup_Validator_URI =
                 http://validator.w3.org/check?uri=%s
               CSS_Validator_URI =
                 http://jigsaw.w3.org/css-validator/validator?uri=%s

            "Doc_URI" is a URI used for linking to the documentation, and CSS and JavaScript files in the
            dynamically generated content of the link checker.  The default is:

               Doc_URI = http://validator.w3.org/docs/checklink.html

            "Connection_Cache_Size" is an integer denoting the maximum number of connections the link checker
            will keep open at any given time.  The default is:

               Connection_Cache_Size = 2

ENVIRONMENT

       checklink uses the libwww-perl library which has a number of environment variables affecting its
       behaviour.  See "SEE ALSO" for some pointers.

       W3C_CHECKLINK_CFG
            If set, overrides the path to the configuration file.

SEE ALSO

       The documentation for this program is available on the web at
       <http://validator.w3.org/docs/checklink.html>.

       LWP, Net::FTP, Net::NNTP, Net::IP, perlre.

AUTHOR

       This program was originally written by Hugo Haas <hugo@w3.org>, based on Renaud Bruyeron's checklink.pl.
       It has been enhanced by Ville Skyttä and many other volunteers since.  Use the <www-validator@w3.org>
       mailing list for feedback, and see <http://validator.w3.org/docs/checklink.html#csb> for more
       information.

       This manual page was originally written by Frédéric Schütz <schutz@mathgen.ch> for the Debian GNU/Linux
       system (but may be used by others).

COPYRIGHT

       This program is licensed under the W3C® Software License,
       <http://www.w3.org/Consortium/Legal/copyright-software>.