WEBFS(4)                                                 WEBFS(4)

     NAME
          webfs - world wide web file system

     SYNOPSIS
          webfs [ -A useragent ] [ -T timeout ] [ -m mtpt ] [ -s
          service ]

     DESCRIPTION
          Webfs presents a file system interface to the parsing and
          retrieving of URLs.  Webfs mounts itself at mtpt (default
          /mnt/web), and, if service is specified, will post a service
          file descriptor in /srv/service.

          If the environment variable httpproxy is set, all HTTP
          request initiated by webfs will be made through that proxy
          url.

          Webfs presents a three-level file system suggestive of the
          network protocol hierarchies ip(3) and ether(3).

          The top level contains the two files: ctl, and clone.

          The top level ctl file is used to maintain parameters global
          to the instance of webfs. Reading the ctl file yields the
          current values of the parameters.  Writing strings of the
          form ``attr value'' sets a particular attribute.

          The following global parameters can be set:

          useragent
               Sets the HTTP user agent string.

          timeout
               Sets the request timeout in seconds.

          flushauth url
               Flushes any associated authentication information for
               resources under url or all resources if no url was
               given.

          preauth url realm
               Preauthenticates all resources under url with the given
               realm using HTTP Basic authentication. This will cause
               webfs to preemptively send the resulting authorization
               information not waiting for the server to respond with
               an HTTP 401 Unauthorized status.

          The top-level directory also contains numbered directories
          corresponding to connections, which may be used to fetch a
          single URL.  To allocate a connection, open the clone file

     Page 1                       Plan 9             (printed 7/24/14)

     WEBFS(4)                                                 WEBFS(4)

          and read a number n from it.  After opening, the clone file
          is equivalent to the file n/ctl.  A connection is assumed
          closed once all files in its directory have been closed, and
          is then will be reallocated.

          Each connection has a URL attribute url associated with it.
          This URL may be an absolute URL such as
          http://www.lucent.com/index.html or a relative URL such as
          ../index.html. The baseurl attribute sets the URL against
          which relative URLs are interpreted.  Once the URL has been
          set by writing to the ctl file of the connection, its pieces
          can be retrieved via individual files in the parsed direc-
          tory:

          parsed/url
               http://pete:secret@www.example.com:8000/cgi/search?q=kittens#results

          parsed/scheme
               http

          parsed/user
               pete

          parsed/pass
               secret

          parsed/host
               www.example.com

          parsed/port
               8000

          parsed/path
               /cgi/search

          parsed/query
               q=kittens

          parsed/fragment
               results

          If there is associated data to be posted with the request,
          it can be written to postbody.  Opening postbody or body
          initiates the request. If the request fails, then opening
          the body or writing to postbody file will fail and return a
          error string.

          When the body file has been opened, response headers appear
          as files in the connection directory. For example reading
          the contenttype file yields the MIME content type of the
          body data.  If the request was redirected, the URL repre-
          sented by the parsed directory will change to the final

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     WEBFS(4)                                                 WEBFS(4)

          destination.

          The resulting data may be read from body as it arrives.

          The following is a list of attributes that can be set to do
          a connection prior initiating the request:

          url,baseurl
               See above.

          useragent
               Sets a custom useragent string to be used with the
               request.

          contenttype
               Sets the MIME content type of the postbody.

          request
               Usually, the HTTP method used is POST when postbody
               file is opend first or GET otherwise. This can be over-
               ridden with the request attribute so send arbitrary
               HTTP requests.

          headers
               Adds arbitrary HTTP headers to be send with the
               request.

     EXAMPLE
          /rc/bin/hget is a simple client.

     SOURCE
          /sys/src/cmd/webfs

     SEE ALSO
          webcookies(4), hget(1)

     DIAGNOSTICS
          For cookies to work, webcookies(4), should be running and
          mounted on /mnt/webcookies otherwise cookies will be
          ignored.

     HISTORY
          Webfs first appeared in Plan 9 from Bell Labs. It was
          rewritten from scratch for 9front (January, 2012).

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