NAME

telescope — multi-protocol browser

SYNOPSIS

DESCRIPTION

telescope is an interactive browser that supports the Finger, Gemini and Gopher protocols. telescope features tabs, a minibuffer, interactive completions, bookmarks and out-of-band TOFU verification.

The arguments are as follows:

-C, --colours

Show all available colors and exit. This option can also be spelled --colors.

-c config

Specify an alternative configuration file. By default ~/.config/telescope/config is loaded.

-h, --help

Display version, usage and exit.

-n

Configtest mode. Only check the configuration file for validity.

-S, --safe

“Safe” (or “sandbox”) mode. Prevent telescope from writing files to the disk and to acquire the lock, allowing to run multiple instances at the same time. telescope still loads the session file and the custom about pages.

-v, --version

Display version and exit.

UI CONCEPTS

telescope interface is divided into four areas: the tabline, the body, the modeline and the echoarea/minibuffer.

The tabline is always at the top of the screen and displays the tabs separated by a vertical line. When there are more tabs than the size of the window allow to display, the characters ‘<’ or ‘>’ are shown at the start/end of the tabline to indicate that there are more tabs in that direction.

The body occupies the majority of the visible area. It contains the current page and optionally a side window.

The modeline is the second to last row of the screen. It shows some information about the page: a spinner when the page is loading, the trust level, the document type, the scroll offset and the URL.

The echoarea is usually the last line of the screen. Messages are often showed there, and link addresses too. The echoarea is also used to obtain input from the user. When commands like swiper or link-select are invoked, the minibuffer area grows to show possible completions.

TOFU

telescope aims to use the “Trust, but Verify (where appropriate)” approach for TOFU (“Trust On First Use”). The idea is to define three level of verification for a certificate:

untrusted

(‘!’) the server fingerprint does NOT match the stored value.

trusted

(‘v’) the server fingerprint matches the store one.

verified

(‘V’) the fingerprint matches and has been verified out-of-band.

The trust level of the page is indicated in the modeline with the indicated character.

Most of the time the “trusted” level is enough, but where is appropriate users should be able to verify out-of-band the certificate.

At the moment, there is no built-in support for an out-of-band verification though.

SUPPORTED PROTOCOLS

The following protocols are supported:

about:

About pages are telescope internal page. See about:about for a list of all these pages.

file://

File types know to telescope, such as .gmi, .gemini, .txt, .md, .markdown, .diff or .patch, can be viewed inside the application. Types of local files are detected solely based on the file extension. On some systems, such as OpenBSD, only files inside special directories (like /tmp or ~/Downloads) are available.

finger://

Finger URLs are interpreted as follows:

• the host is determined by the host name portion of the URL
• if the user portion of the URL is provided, it's interpreted as the user to finger, otherwise the path component will be used

thus finger://user@hostname and finger://hostname/user are treated as the same URL.

gemini://

Gemini is fully supported, with the exception of client-certificates.

gopher://

Gopher support is limited to items type 0, 1 and 7. All text is assumed to be encoded in UTF-8 (or ASCII).

User-entered URLs, given as argument on the command line or entered with load-url, are intepreted with a simple heuristic:

• if it's a proper absolute URL then use it as-is,
• if it starts with “./” or “/” assume it's a file:// URL,
• otherwise assume it's a Gemini URL.

CONFIGURATION FILE

During the startup, telescope reads the configuration file at ~/.config/telescope/config or ~/.telescope/config.

It's possible to load a custom configuration file using the -c flag.

telescope will also load a file called config-TERM, where “TERM” is the name of the terminal type (i.e. the TERM environment variable), if it exists.

The format of the configuration file is fairly flexible. The current line can be extended over multiple ones using a backslash (‘\’). Comments can be put anywhere in the file using a hash mark (‘#’), and extend to the end of the current line, but backslashes can't be used to extend comments over multiple lines.

The following constructs are available:

bind map key cmd

Bind key to the function cmd in the keymap map. Valid values for map are “global-map” (i.e. when the user is viewing a page) and “minibuffer-map” (i.e. when the minibuffer has the focus.) key follows the same syntax described in DEFAULT KEY BINDINGS and all the possible functions are listed in INTERACTIVE COMMANDS.

proxy proto via url

Use url as proxy for all URLs with protocol proto. url must be a Gemini URI without path, query and fragment component.

set opt = val

Set the option opt to the value val. Valid options are:

autosave

(integer) If greater than zero, save the session after the specified amount of seconds after some events happens (new or closed tabs, visited a link ...) Defaults to 20.

dont-wrap-pre

(integer) If nonzero, don't wrap preformatted blocks. Defaults to 0.

download-path

(string) The default download path. Defaults to /tmp.

emojify-link

(integer) If nonzero, when the text of a link starts with an emoji followed by a space, use that emoji as line prefix. Defaults to 1.

enable-colors

(integer) If nonzero, enable colours. Defaults to 0 if NO_COLORS is set, 1 otherwise.

fill-column

(integer) If greater than zero, lines of text will be formatted in a way that don't exceed the given number of columns. Defaults to 80.

fringe-ignore-offset

(integer) If nonzero, the fringe doesn't obey to olivetti-mode. Defaults to 1.

hide-pre-blocks

(integer) If nonzero, hide by default the body of the preformatted blocks. Defaults to zero. push-button can be used to toggle the visibility per-block.

hide-pre-closing-line

(integer) If nonzero, hide the closing line of preformatted blocks. Defaults to 0.

hide-pre-context

(integer) If nonzero, hide the start and end line of the preformatted blocks. If both hide-pre-context and hide-pre-blocks are nonzero, preformatted blocks are irremediably hidden. Defaults to zero.

new-tab-url

(string) URL for the new tab page. Defaults to “about:new”.

max-killed-tabs

(integer) The maximum number of closed tabs to keep track of, defaults to 10. Must be a positive number; if zero, don't save closed tabs at all.

olivetti-mode

(integer) If nonzero, enable olivetti-mode Defaults to 1.

tab-bar-show

(integer) If tab-bar-show is -1 hide the tab bar permanently, if 0 show it unconditionally. If it's 1, show the bar only when there is more than one tab. Defaults to 1.

update-title

(integer) If nonzero, set the terminal title to the page title. Defaults to 1.

style name option

Change the styling of the element identified by name. Multiple options may be specified within curly braces. Valid style identifiers are:

line

the area outside the lines in the body of the page.

line.compl

the completions.

line.compl.current

the current completion.

line.help

text in the *Help* buffer.

line.download.ongoing

an ongoing download

line.download.done

a completed download

line.download.info

informational text in the *Downloads* buffer.

line.fringe

(virtual) lines draw after the end of a buffer.

line.text

text lines.

line.link

link lines.

line.title1..3

headings

line.item

item lines.

line.quote

quotes.

line.pre.start

the heading of a preformatted block.

line.pre

the content of a preformatted block.

line.pre.end

the closing line of a preformatted block.

download

the download pane

minibuffer

the minibuffer.

modeline

the modeline.

tabline

the tabline.

tabline.tab

the non-focused tabs.

tabline.current

the focused tab.

Valid options are:

attr prefix [line [trail]]

Sets the text attributes. If only one value is given, line and trail default to that; if two values are given then trail defaults to prefix. Each attribute is a comma-separated list of keywords:

normal

no attributes.

standout

best highlighting mode for the terminal.

underline

underlines the text.

reverse

reverses background/foreground colors.

blink

makes the text blinking.

dim

half bright.

bold

extra bright or bold.

Only the style identifiers with the “line.” prefix accept up to three attributes. The other will only use the first one given.

bg prefix [line [trail]]

Sets the background color. Follows the same behaviour as attr regarding the optional parameters. The colour is one of black, red, green, yellow, blue, magenta, cyan and white; colour0 to colour255 (or color0 to color255) from the 256-colour set; default for the default colour.

fg prefix [line [trail]]

Sets the foreground color. It behaves just like bg.

prefix prfx [cont]

Sets the prefix for the current line type to prfx and cont as the prefix for the continuation lines (i.e. when a long line gets wrapped.) If cont is not given its value will be the same of prfx.

DEFAULT KEY BINDINGS

The default key bindings are very similar to GNU Emacs, but care has been taken to include also bindings familiar for vi(1) and “CUA” users. In the following examples, C-x means Control-x, M-x means Meta-x, where the Meta key may be either a special key on the keyboard or the ALT key; otherwise ESC followed by the key X works as well, and C-M-x means to press the key X together with both Control and Meta.

Keys are usually a single character, like ‘p’ or ‘n’, but some special keys are accepted as well.

INTERACTIVE COMMANDS

Follows the documentation for the interactive commands. These commands can be bound to a key or executed with execute-extended-command.

ENVIRONMENT

When telescope is started, it inspects the following environment variables:

HOME

The user's login directory.

NO_COLORS

To decide whether to use colors or not. The content of the variable doesn't matter.

TERM

The user's terminal name.

XDG_CACHE_HOME, XDG_CONFIG_HOME, XDG_DATA_HOME

If defined can alter the default location of the files used.

FILES

By default telescope follows the XDG Base Directory Specification. However, if ~/.telescope exists, XDG is ignored and all the files are stored inside it. The usage of XDG_CACHE_HOME, XDG_CONFIG_HOME and XDG_DATA_HOME can further alter the location of these files.

~/.config/telescope/config

Default configuration file.

~/.local/share/telescope/pages/about_*.gmi

Overrides for built-in about: pages.

~/.local/share/telescope/bookmarks.gmi

Bookmarks file.

~/.local/share/telescope/known_hosts

Hash of the certificates for all the known hosts. Each line contains three fields: hostname with optional port number, hash of the certificate and a numeric flag.

~/.cache/telescope/lock

Lock file used to prevent multiple instance of telescope from running at the same time.

~/.cache/telescope/session

The list of tabs from the last session.

EXAMPLES

It's possible to browse “the small web” (i.e. simple websites) by using programs like the duckling-proxy by defining a proxy in ~/.config/telescope/config:

proxy http via "gemini://127.0.0.1:1965"
proxy https via "gemini://127.0.0.1:1965"

To load telescope without any configuration

telescope -c /dev/null

STANDARDS

XDG Base Directory Specification, https://specifications.freedesktop.org/basedir-spec/latest/.

ACKNOWLEDGEMENTS

The “Trust, but verify (where appropriate)” TOFU scheme was firstly suggested by thfr: gemini://thfr.info/gemini/modified-trust-verify.gmi.

AUTHORS

The telescope program was written by Omar Polo <op@omarpolo.com>.

CAVEATS

telescope assumes a UTF-8 environment and doesn't try to cope with other encodings. This can cause strange rendering issues if you're lucky, or possibly weird thing happening depending on your locale and terminal emulator.

The algorithm used for text-wrapping is naive and doesn't really work for languages that make heavily use of glyphs composed by multiple UNICODE codepoints.

BUGS

There's no UI for out-of-band certificates validation.