Ubuntu Manpage: vf1 — command line gopher client

NAME

     vf1 — command line gopher client

SYNOPSIS

     vf1 [-h] [--bookmarks] [--debug] [--tls] [url ...]

DESCRIPTION

     vf1 is an interactive command line gopher client.  It presents a prompt to the user, who can
     then enter commands to perform actions.

     Only a small number of commands are needed to get around, and most of them can be
     abbreviated to one or two chars, so with practice very quick navigation of gopherspace is
     possible.  See the COMMANDS section for more details.

     The options are as follows:

     -h, --help
             Display a short help message and exit.

     --bookmarks
             Immediately navigate to bookmarks upon starting.

     --debug
             Start with debug mode enabled.

     --tls   Start in TLS mode.  See the TLS MODE section for more details.

     url ...
             The Gopher URL(s) to open.  If more than one URL is provided, these are queued in a
             tour.

COMMANDS

All vf1 commands are listed below. Most commands operate on an implicit operand from the
very limited internal state which vf1 maintains.

This state includes the “lookup,” which is a list of items (locations) in Gopherspace with
numeric indices attached. Indices begin from 1. Upon startup, the lookup is empty.
Whenever a gopher menu is visited, the contents of that menu become the contents of the
lookup, replacing any previous contents. Some commands, such as search, history, or links
overwrite the lookup with their results. At any time, the lookup can be reset to the
contents of the most recently visited gopher menu with the ls command.

In addition to the lookup, vf1 is aware of exactly one active item (the item the user is
currently viewing). Usually, the active item is one of the items in the lookup, and if so
vf1 knows its index.

Most vf1 commands operate on either the lookup, or the active item.

In addition to the commands listed below, users can enter a numeric index. vf1 will then
navigate to the corresponding item in the lookup, and that item will become the active item.

a, add Add the URL of the current item to the bookmarks menu.

b, back
Go back to the previous item in the history.

bb, blackbox
Display contents of flight recorder, showing statistics for the current gopher
browsing session.

bm, book, bookmarks
Show the current bookmarks menu.

cat Process the text of the current item with the cat(1) command.

exit Exit VF-1. Go forward to the next item in the history.

f, fold
Process the text of the current item with the fold(1) command, wrapping lines at 70
characters.

fo, forward
Go forward to the next item in the history.

g, go url | mark
Visit a gopher URL or marked item, making it the active item.

handler [mimetype program]
List or set handlers for different MIME types. See HANDLERS section below for more
details.

help [command]
Display help information for a command, or list all commands with help information
available.

h, hist, history
Display the history.

l, less
Process the text of the current item with the less(1) command.

li, links
Extract URLs from the text of the current item, and populate the lookup with them.

ls [-l]
Set the lookup to the contents of the most recently visited gopher menu and then
list the lookup's contents. If invoked as ls -l the listing will include the URL of
each menu item.

m, mark [mark]
Mark the current item with a single letter. This letter can then be passed to the
go command to return to the current item later. Lists all defined marks when no
argument is given.

n, next
Go to the item which is after the current item in the lookup.

p, prev, previous
Go to the item which is before the current item in the lookup.

q, quit
Exit VF-1.

r, reload
Reload the current item.

root Visit the root gopher item of the server hosting the current item.

s, save [filename]
Save an item to the filesystem. save saves the current item with an automagic
filename derived from its gopher selector. save filename saves the current item
with the specified filename. save n saves the item at lookup index n with an
automagic filename. save n filename saves the item at lookup index n with the
specified filename.

/, se, search pattern
Search the lookup (case insensitive).

set [option value]
Change the value of a setting, or view its current value. Shows all current value
options if no arguments are given. See the SETTINGS section below for more details.

tls Toggle TLS mode on or off. See the TLS MODE section for more details.

t, tour [item ...]
Visit the next item in, or add an item to, the “tour” - a FIFO queue of gopher
items. If no arguments are provided, the next item in the tour is visited. Items
from the lookup can be added with a list of indices like tour 1 2 3 4, or
consecutive ranges like tour 1-4. All items in the lookup can be added with tour *.
Items not in the lookup can be added by their URL with tour url. The current tour
queue can be listed with tour ls and scrubbed with tour clear.

up, u Go up one directory in the path.

url Show the URL of the current item.

v, veronica [query]
Submit a search query to the Veronica 2 search engine.

HANDLERS

     vf1 uses external programs as “handlers” to present different gopherspace content to the
     user.  Even when visiting a plain text file with item type 0, vf1 uses (by default) the unix
     command cat(1) to display that file on the screen, rather than using a Python print() call.
     Users have full control over which external programs are used for different content, so the
     user experience can be customised to taste.

     Handlers are assigned on the basis of MIME types.  The gopher protocol has no concept of
     MIME type, so vf1 assigns each item a MIME type itself in the manner described in the
     section MIME type assignment below.

     A list of the current handler assignments can be viewed at any time by running the handler
     command.  The default handlers that ship with vf1 are:

           MIME type          handler
           application/pdf:   xpdf %s
           audio/mpeg:        mpg123 %s
           audio/ogg:         ogg123 %s
           image/*:           feh %s
           text/*:            Ta cat %s
           text/html:         lynx -dump -force_html %s

     The handler command can be used to change these handlers, or set handlers for new MIME
     types.  For example, users who prefer w3m(1) over lynx(1) for handling HTML content could
     run:

           VF-1> handler text/html w3m -dump %s

     The specified handler will be run as a shell command, with the temporary file containing the
     content of the current gopher item replacing any occurrences of %s.  Pipe syntax can be used
     to pass gopher content through multiple text filters to achieve the desired appearance.

     The ‘*’ wildcard can be used when specifying handler MIME types, e.g.  ‘image/*’ allows
     using a single program to handle any kind of image.  Handlers without wildcards take
     precedence over handlers with wildcards.  In other words, if one handler is specified for
     ‘image/jpeg’ and a different handler for ‘image/*’, the ‘image/jpeg’ handler will be used
     for JPEGs and the ‘image/*’ handler will be used for all other images.

   MIME type assignment
     vf1 assigns MIME types to gopher items as follows:

     ·   Item types 0 and 1 are assigned MIME type ‘text/plain’

     ·   Item type h is assigned MIME type ‘text/html’

     ·   Item type g is assigned MIME type ‘image/gif’

     For all other item types, vf1 attempts to guess a MIME type from the file extension of the
     last component of the selector, using the ‘mimetypes’ module from the Python standard
     library.  This usually results in a reliable identification assuming the file has an
     extension and the author of the gopher content is not being deliberately deceptive.

     If the selector has no file extension, or the extension is not recognised by the ‘itemtypes’
     module, vf1 will use the unix program file(1) to attempt to guess a MIME type by actually
     inspecting the content of the file.

     In accordance with the idea that gopher item types, which are a standard part of the
     protocol, should take precedence over any other attempt at inferring MIME type, which is not
     a standard part of the protocol, if an item in gopherspace is listed with itemtype ‘I’ or
     ‘s’ and one of the above methods returns a MIME type which does not begin with ‘image/’ or
     ‘sound/’ respectively, vf1 will default to ‘image/jpeg’ or ‘audio/mpeg’ respectively.  This
     should only happen in highly unusual circumstances and suggests a poorly or maliciously
     configured gopher server.

TEXT ENCODING

     vf1 attempts to decode the content received for any text-based item types (e.g. 0, 1, 7, h)
     as UTF-8.  Most content in gopherspace is ASCII-encoded, and since UTF-8 is backward
     compatible with ASCII, this will generally “just work”.  If the received content cannot be
     decoded as UTF-8, one of two possible things will happen:

     If the ‘chardet’ Python module is installed, vf1 will use it to attempt to automatically
     detect the encoding used and decode the text appropriately.  Note that pip etc. will not
     install ‘chardet’ automatically when installing vf1, as vf1 does not formally depend on
     ‘chardet’.  It uses it opportunistically, so that it can still be easily installed and used
     on systems where ‘chardet’ is not or cannot be installed.

     If ‘chardet’ is not installed, or if ‘chardet’ cannot identify an encoding with confidence
     exceeding 0.5, vf1 will attempt to fall back to a single, user-specified alternative
     encoding.  This encoding can be set as follows:

           VF-1> set encoding koi8-r

     The default fall back encoding is iso-8559-1, which is used by the popular gopher site .:
     floodgap.com Users who routinely visit gopher sites encoded with some other encoding may
     consider using an RC file (see below) to automatically set the alternative encoding at start
     up.

TLS MODE

     vf1 supports TLS connections.  This is an experimental feature, and TLS connections are not
     supported by the majority of gopher servers.  As such, TLS support must be explicitly
     activatd by using the command to enable TLS mode (aka "Battloid mode").  When TLS mode is
     enabled, all gopher requests will be made over TLS, so most requests will fail when a
     connection to the server cannot be established.  TLS mode must be explicitly deactivated to
     resume browsing unencrypted gopherspace.

SETTINGS

     The following miscellaneous settings can be adjusted with the command.

     color_menus
             If set to true, items in gopher menus will be color coded according to item type,
             using ANSI escape codes.  Default value is false.

     debug   If set to true, detailed debugging information will be printed to stdout when
             commands are run.  Default value is false.

     encoding
             Fallback text encoding to use if received gopher content cannot be decoded as UTF-8.
             See the TEXT ENCODING section for more details.  Default value is iso-8859-1.

     ipv6    If set to true, vf1 will preferentially attempt to connect to gopher servers via
             IPv6 if a AAAA DNS record is found.  If the IPv6 connection fails, vf1 will
             automatically retry with IPv4.  Default value is true.

     timeout
             Time to wait, in seconds, when trying to connect to a gopher server before giving
             up.  Default value is 10.

FILES

     ~/.vf1-bookmarks.txt  This file stores gopher bookmarks, in a simple gophermap format
                           (without hosts or ports).  Use add to add the current URL to the
                           bookmark list.
     ~/.config/vf1/vf1rc
     ~/.config/.vf1rc
     ~/.vf1rc              Upon startup, vf1 will search for a file with one of these names, a
                           so-called RC file (see below).The names are listed above in order of
                           preference and vf1 will stop after the first one it finds, e.g. if
                           both ~/.config/vf1/vf1rc and a ~/.vf1rc exist then then ~/.vf1rc will
                           be ignored.

   RC FILE
     If an RC file is found, each line of the file will be executed as a vf1 command before the
     prompt is displayed.This allows users to script certain commands that should be run every
     time vf1 is started.  This permits, for example:

     ·   Permanently configuring item type handlers by putting handler commands in the RC file.

     ·   Permanently configuring the preferred non-UTF-8 encoding, or other options, by putting
         set commands in the RC file.

     ·   Setting a “home page” by putting a go command in the RC file.

     ·   Starting a tour through a list of favourite sites by putting tour commands in the RC
         file.

EXAMPLES

     See the vf1-turorial(7) for a comprehensive introduction to the work flow of vf1

     Start vf1:

           vf1

     Start vf1 and immediately open to bookmark list:

           vf1 --bookmarks

     Visit the zaibatsu:

           vf1 zaibatsu.circumlunar.space

STANDARDS

     vf1 is a gopher client conforming to RFC 1436 ⟨https://tools.ietf.org/html/rfc1436⟩.

TRIVIA

     vf1 is named after the VF-1 Valkyrie aircraft from the classic '80s anime series Super
     Dimension Fortress Macross, in recognition of the role that the SDF Public Access Unix
     system ⟨gopher://sdf.org⟩, named after the same series, has played in keeping Gopherspace
     alive in the 21st century.

AUTHORS

     Solderpunk ⟨solderpunk@sdf.org⟩
     Alex Schroeder ⟨alex@gnu.org⟩
     Joseph Lyman ⟨tfurrows@sdf.org⟩
     Adam Mayer ⟨https://github.com/phooky⟩
     Paco Esteban ⟨paco@onna.be⟩