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VF1(1) General Commands Manual VF1(1)

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:

, --help
Display a short help message and exit.
Immediately navigate to bookmarks upon starting.
Start with debug mode enabled.
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.

, add
Add the URL of the current item to the bookmarks menu.
, back
Go back to the previous item in the history.
, blackbox
Display contents of flight recorder, showing statistics for the current gopher browsing session.
, book, bookmarks
Show the current bookmarks menu.
Process the text of the current item with the cat(1) command.
Exit VF-1. Go forward to the next item in the history.
, fold
Process the text of the current item with the fold(1) command, wrapping lines at 70 characters.
, forward
Go forward to the next item in the history.
, go url | mark
Visit a gopher URL or marked item, making it the active item.
[mimetype program]
List or set handlers for different MIME types. See HANDLERS section below for more details.
[command]
Display help information for a command, or list all commands with help information available.
, hist, history
Display the history.
, less
Process the text of the current item with the less(1) command.
, links
Extract URLs from the text of the current item, and populate the lookup with them.
[-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.
, 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.
, next
Go to the item which is after the current item in the lookup.
, prev, previous
Go to the item which is before the current item in the lookup.
, quit
Exit VF-1.
, reload
Reload the current item.
Visit the root gopher item of the server hosting the current item.
, 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).
[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.
Toggle TLS mode on or off. See the TLS MODE section for more details.
, 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.
, u
Go up one directory in the path.
Show the URL of the current item.
, 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 () 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:

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 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, 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.

If set to true, items in gopher menus will be color coded according to item type, using ANSI escape codes. Default value is false.
If set to true, detailed debugging information will be printed to stdout when commands are run. Default value is false.
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.
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.
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

SEE ALSO

vf1-tutorial(7)

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>

August 31, 2019 All Operating Systems