Using your ship
Your urbit (also called your ship) is a persistent Unix process that you mainly control from the console.
Shutdown
You can turn your urbit off with Ctrl-d from the Chat or Dojo prompts.
You can force-quit your urbit with Ctrl-z from anywhere.
Restart
To restart your urbit simply pass the name of your pier:
$ ./urbit some-planet
or
$ ./urbit comet
Logging
To log an urbit's command line output to a file, use script:
$ script urbit.log ./urbit your-urbit
Moving your pier
Piers are designed to be portable, but it must be done while the urbit is not running. Urbit networking is stateful, so you can't run two copies of the same urbit in two places.
To move a pier, simply move the contents of the directory it lives in.
To keep these files as small as possible we usually use the --sparse
option in tar. With a pier your-urbit/, something like this should work:
tar -Scvzf ~/your-urbit.tar.gz ~/your-urbit/ scp your-old-server:~/your-urbit.tar.gz your-new-server:~
Then to unzip it, on your other Unix server, run:
tar xfvz your-urbit.tar.gz
Delete the tar file, and, after installing Urbit on your new server, start your urbit back up with:
./urbit your-urbit
Console
Your Urbit terminal is separated into two parts: the prompt (the bottom line) and the record (everything above that). The record is shared; all the output from all the apps in your command set appears in it. The prompt is multiplexed.
In the CLI, Urbit apps can process your input before you hit return. To see this in action try entering ) as the first character at the Dojo prompt. Since there is no Dojo command or Hoon expression that starts with ')', the Dojo rejects it.
Ctrl-x - Switches the prompt between running console apps
Ctrl-c - Crash current event. Processed at the Unix layer and prints a stack
trace.
Ctrl-d - From Chat or Dojo, stops your Urbit process.
Ctrl-z - Stops the Urbit process from anywhere.
↑ / ↓ - History navigation
The following emacs-style key bindings are available:
Ctrl-a Cursor to beginning of the line (Home)
Ctrl-b Cursor one character backward (left-arrow)
Ctrl-e Cursor to the end of the line (End)
Ctrl-f Cursor one character forward (right-arrow)
Ctrl-g Beep; cancel reverse-search
Ctrl-k Kill to end of line
Ctrl-l Clear the screen
Ctrl-n Next line in history (down-arrow)
Ctrl-p Previous line in history (up-arrow)
Ctrl-r Reverse-search
Ctrl-t Transpose characters
Ctrl-u Kill to beginning of line
Ctrl-y Yank from kill buffer
Landscape
On startup Urbit tries to bind to localhost:80. If you're already running something on port 80 -- such as any other HTTP server, or another urbit -- you'll find the urbit that you just started on 8080, 8081, and so on. For planets only, we also proxy web domains through Urbit's own servers. Any planet ~your-urbit is also at your-urbit.arvo.network, but only after you set up DNS.
Once running, you can sign into Landscape, your ship’s web interface, from http://localhost or https://your-urbit.arvo.network. Since our HTTPS isn't audited / battle tested, we just call it "secure" HTTPS. You can find that on 8443. Or 8444 (and so on) if you're already running something on 8443.
Moons
Planets can spawn moons, which are meant for connected devices: phones, smart TVs, digital thermostats. The basic idea is that your planet runs permanently in a data center somewhere, while moons run on all your devices. Each planet can issue ~4 billion (2^32) moons.
To generate a random moon from your planet, run:
~sampel-palnet:dojo> |moon
moon: ~faswep-navred-sampel-palnet
\/0w5cT5t.wCO6i.~e1xg.Oz0qb.QNO6I.3Kt2T.h9M9F.U3vU~.X3Qu0.gtb19.IYTkY.80kWZ.SI\/
EUE.DXa8i.TiDof.o3-1C.RHLKS.k81M0.ecz5o.ic0Bg.600g1
\/ \/
You must manually edit the output of |moon to get the correct format for the <key>:
-
strip out the
/ -
combine into one line, omitting spaces
<key> would be 0w5cT5t.wCO6i.~e1xg.Oz0qb.QNO6I.3Kt2T.h9M9F.U3vU~.X3Qu0.gtb19.IYTkY.80kWZ.SIEUE.DXa8i.TiDof.o3-1C.RHLKS.k81M0.ecz5o.ic0Bg.600g1
in this example.
Put <key> in a file and that file becomes <keyfile>.
To breach a moon -- that is, to reset its presence on the network so that it's treated as a freshly spawned ship by others -- run from the parent ship:
|moon-breach ~faswep-navred-sampel-palnet
To cycle the keys of a moon without breaching, run:
|moon-cycle-keys ~sampel-sipnym-wicdev-wisryt
You can use the resulting output in the same installation flow from the Installing Urbit guide, following the same scheme as for booting a planet. That scheme is:
$ ./urbit -w <moonname> -G <key> -c <piername>
or
$ ./urbit -w <moonname> -k <keyfile> -c <piername>
The -c <piername> argument is not required, but it is recommended; otherwise,
the resulting directory is a rather unwieldy moon name.
Here's how an example moon might be booted:
$ ./urbit -w faswep-navred-sampel-palnet -G <key> -c mymoon
or
$ ./urbit -w faswep-navred-sampel-palnet -k <keyfile> -c mymoon
Moons are automatically synced to their parent %kids desk, and can control applications on their parent planet using |link.
Continuity breaches
While the Urbit network is in this alpha state, we sometimes have to reboot the whole network. This happens either when major changes need to be shipped or we hit a bug that can't be fixed over the air.
Because Urbit networking is stateful we call this a continuity breach. Everything has to be restarted from scratch. Your pier will continue to function after we have breached, but it won’t connect to the rest of the Urbit network.
When this happens, back up any files you'd like to save, shut down your urbit, and recreate it (as if you were starting for the first time).
DNS proxying
We have a system that lets you request a domain name for your ship in the form of ship.arvo.network, where ship is your ship's name minus the ~. This allows users to access their ships remotely using Landscape, our graphical web interface.
Stars and planets follow the same process DNS proxying process, and galaxies have their own requirements. Moons and comets are not supported.
Planets and Stars
For a planet or star's DNS proxying request to be made and fulfilled, they must be hosting their ship someplace with a public IP address, and its HTTP server must be listening on port 80.
To get ship.arvo.network on a planet or star, you must set up DNS routing with its parent ship by starting the :dns app.
To do so, simply run this command in your ship's Dojo:
> :dns|request
You'll then be prompted to enter the public IP address of your ship. You can also pass the IP address as an argument, using the .0.0.0.0 (@if) syntax. For example:
> :dns|request .1.2.3.4
:dns, running locally, will make an HTTP request to that IP address on port 80 to confirm that it is itself available at that IP and port. If that fails, you'll receive a %bail-early message in :chat-cli; this request will retry a few times. If the self-check is successful, the request is relayed to ~zod, and you'll receive a message saying, request for DNS sent to ~zod. Once ~zod has acknowledged receipt of the request, your local :dns app will send a :chat-cli message saying awaiting response from ~zod.
The request will be picked up shortly, and the ship.arvo.network DNS record will be set to the given IP address. Once that's set up, ~zod will be notified and ~zod will, in turn, notify your ship. That ship will now try to verify that it can reach itself on ship.arvo.network over port 80. If it can't, it'll send a message saying, unable to access via ship.arvo.network. If it can, it will configure itself with that domain and say confirmed access via ship.arvo.network.
Great! You're set up now. Try accessing your ship.arvo.network in your browser to use Landscape; we recommend Chrome or Brave.
Galaxies
Galaxies are already required to have separate DNS entry at galaxy.urbit.org. There's no automated process for getting that binding, so if you're a galaxy-holder, get in touch with us at support@urbit.org.
There is a command for galaxies that will try to re-use their already-necessary Ames DNS entry for HTTPS:
> :dns|auto
This will make HTTP-requests to self-check availability over galaxy.$AMES-DOMAIN (currently galaxy.urbit.org), where galaxy is the galaxy's name minus the ~.
Otherwise, :dns|auto works the same as :dns|ip does with stars and planets: if it's available or unavailable, Chat messages, and so on.
More information
Configuring a ship's domain causes the :acme app to request an HTTPS certificate for that domain from LetsEncrypt. Note that LetsEncrypt also requires that the HTTP server be listening on port 80. If the certificate request fails, :acme will send a :chat-cli message with an explanation. Once the certificate is successfully retrieved, :acme will install it, causing the HTTP servers to restart. A secure server will be started on port 443 (the HTTPS default) if it's available. Otherwise, it will try 8443, and then increment to the next port until it can successfully bind one.
The built-in logic for listening on port 80 is similar. Urbit tries to bind port 80; if it cannot, it tries 8080, then increments until it can bind a port. Port 80 is available to unprivileged process on recent version of macOS. Otherwise, the process needs to either be run as root, or be given special permission (CAP_NET_BIND on Linux).
Messaging
Let’s get started using the :chat-cli application, also known more simply as Chat. It's the simplest way to talk to people using the command line interface.
Quickstart
The most common uses of :chat-cli right now are communicating over a public chat channel on ~dopzod/urbit-help. Everyone is more than welcome in ~dopzod/urbit-help. It's the place to get help, ask questions and chat about Urbit in general.
Note that largely equivalent functionality is also available through Chat's web UI in landscape. This is available from your ship’s URL address, mentioned earlier in this guide.
Joining a chat
In :chat-cli, any kind of medium for a message is called a chat. There are four "types" of chats, but for now we'll be dealing with the channel, a publicly accessible chatroom for general use. We'll discuss the other three kinds in the chat management section later on.
Let's join the ~dopzod/urbit-help channel. Use ctrl-x to switch from the Dojo prompt to the Chat prompt.
Then:
~sampel-palnet:chat-cli/ ;join ~dopzod/urbit-help
Now that you're in, try post a line to ~dopzod/urbit-help:
~sampel-palnet:chat-cli= Hello, world!
You'll see your message printed below messages from others that came before it. You can always type ;chats in the chat-cli prompt to list all the chats you're in:
~sampel-palnet:chat-cli= ;chats
~dopzod/urbit-help
Glyphs will be automatically assigned to channels, but have the option of binding a glyph (single non-alphanumeric character) to the channel you're joining; the syntax is in the form of ;join ~dopzod/books +. The chosen glyph will be the symbol that ends your prompt, and it will be what you use as a shortcut to switch to this channel.
~sampel-palnet:chat-cli= ;+
~sampel-palnet:chat-cli+
Use ;leave to unsubscribe from a channel:
~sampel-palnet:chat-cli= ;leave ~dopzod/urbit-help
Now, let's create a channel we can invite some friends to:
~sampel-palnet:chat-cli= ;create channel /my-channel
Now you can tell your friends to ;join ~your-urbit/my-channel.
Hoon
You can use Chat to evaluate Hoon code and share the results with everyone in a chat. To do so, preface your Hoon with #.
~sampel-palnet:chat-cli= #(add 2 2)
This will print as:
~sampel-palnet# (add 2 2)
4
URLs
To share a URL, send it as its own message, with no content before or after it.
~sampel-palnet:chat-cli= https://urbit.org/
This will print as:
~sampel-palnet/ https://urbit.org/
Expanding messages
In the case of URLs, they may be too long to display on a single message line. For Hoon code, the code or result could be big. In :chat-cli, these get shortened when initially printed out. To view the entire contents, you can select the message in various ways.
~sampel-palnet+ some message
----------[240]
~sampel-palnet+ let's try selecting this message!
~sampel-palnet+ another message
~sampel-palnet:chat-cli=
In the above example, we can select the middle message by issuing any of the following command:
;240
;40
;;
;n looks for the last message whose sequence number ends in n. ;; simply picks the second-to-last message.
Detailed message output will look something like this:
? 240
0v5.g7r7l.n0d7m.mp4bn.gp6vr.sm5lj at ~2019.10.17..22.08.27..8a03
~sampel-palnet
to ~dopzod/urbit-help
let's try selecting this message!
Creating and managing chats
As mentioned before, any urbit can host any number of chats. Existing chats can be deleted or modified with various commands. All commands in this section should be sent from the chat-cli> prompt.
Create
Syntax: ;create [type] /name +, where + represents an optional glyph.
Creates and joins a chat, where [type] is any of the following:
channel: public chat. Has a blacklist for write control.village: invite-only chat.journal: publicly readable, invite-only for writing.mailbox: publicly writeable, invite-only for reading.
Let's create an example mailbox:
~sampel-palnet:chat-cli> ;create mailbox /coolbox ^
Delete
Syntax: ;delete /name
Deletes a chat.
Permission management
You can permit and ban people from reading and/or writing to the chats you host, using ;invite and ;banish command respectively.
Syntax: ;invite [rw] /name ~ships
Where rw is either r, w, or rw, representing "read" and "write" permissions.
And where ~ships is a comma-seperated list of ships to invite.
For example, to grant two people full access to a village we created:
~sampel-palnet:chat-cli> ;invite rw /hidden-village ~ravmel-ropdyl, ~rapfyr-diglyt
Similarly, if we later want to revoke the writing permissions for one of them, but still allow them to read new messages, we can run:
~sampel-palnet:chat-cli> ;banish w /hidden-village ~rapfyr-diglyt
Chat glyphs
Glyphs are found at the end of your prompt, as a quick indicator of where your messages will be sent.
Glyphs are assigned by chat hash out of the following list:
! @ # $ % ^ & ( ) - = _ + [ ] { } ; ' \ : " , . < > ?
Alphanumeric characters and |#/*~ are reserved; all others can be manually assigned.
For example, - the glyph at the end of the prompt below might indicates that
messages sent from this prompt will go to some chat with that glyph:
~sampel-palnet:chat-cli-
To see what chat is bound to a glyph, use the ;what command followed by the
glyph in question, or use ;what without specifying a glyph to see all of your
subscriptions which are bound to glyphs. For example, to see =:
~sampel-palnet:chat-cli> ;what =
~dopzod/urbit-help
To see all of your glyph bindings:
~sampel-palnet:chat-cli> ;what
> ~paldev/numismatic-forum
. ~middev/ny-martians
= ~dopzod/urbit-help
When the messaging target doesn't have a glyph, we see their name at the end of
the prompt instead. Here we're talking into ~dannum-mitryl/homework:
~sampel-palnet:chat-cli[~dannum-mitryl/homework]
Bind
Syntax: ;bind [glyph] ~host/chat-name
Assigns the chosen glyph to a chat.
For example:
~sampel-palnet:chat-cli> ;bind + ~dopzod/urbit-help
Unbind
Syntax: ;unbind [glyph] ~host/chat-name
Unassigns the chosen glyph from a chat owned by your ship.
For example:
~sampel-palnet:chat-cli> ;unbind + ~dopzod/urbit-help
If you don't specify a chat, all bindings for that glyph are removed.
Prefixes
Received posts are prefixed with a glyph to let you know what the audience is. You can activate an individual post to see the full audience.
There are a few special-purpose "glyphs":
|- Informational messages*- Posts to a target you don't have a glyph binding for
Configuration
Set audience
;~ship/chat
Set audience to ~ship/chat.
Set audience by glyph
Syntax: ;[glyph]
Set audience to the chat previously bound to the chosen glyph.
Set audience to own chat
Syntax: ;/chat
Set audience to a chat on your own ship.
Miscellaneous configuration
Change timezone
Syntax: ;set timezone [+/-][hours]
Adjust the display of timestamps to a specific timezone. Relative to UTC.
Set width
Syntax: ;set width [number]
Set the rendering width of :chat-cli to a specific number of characters.
(Minimum of 30.)
Show timestamps
Syntax: ;set showtime
Show the timestamp for each message. This is set by default.
Hide timestamps
Syntax: ;unset showtime
Stop showing the timestamp for each message.
Sound notification on
Syntax: ;set notify
Emit a terminal bell sound if your six-syllable ship name is mentioned in a message. This is set by default.
Sound notification off
Syntax ;unset notify
Do not notify when your ship name is mentioned.
Shell
The Dojo is our shell; it processes system commands and returns output. It's a good place to quickly experiment with Urbit. On the surface the Dojo is just a Hoon REPL. On the inside, the Dojo is a system for operating on and transforming data in Urbit.
Quickstart
You can use the Dojo to run arbitrary Hoon code, as well as non-Hoon system commands.
Math
Evaluate a Hoon expression (whitespace matters):
~your-urbit:dojo> (add 2 2)
~your-urbit:dojo> %+ add 2 2
Tall-form Hoon may require multiple lines:
~your-urbit:dojo> %+ add
~your-urbit:dojo< 2
~your-urbit:dojo< 2
Hoon uses something called the subject. The Dojo has its own subject and that's where Hoon's equivalent of variables, called faces, are stored.
Use =var to save faces to the Dojo subject.
~your-urbit:dojo> =foo (add 2 2)
Note, however, that =var is Dojo syntax, not Hoon syntax. You cannot bind a
face in a .hoon file in this way.
System commands
Use =dir to set the current working directory:
~your-urbit:dojo> =dir %/gen
(% represents your current directory. For a complete explanation on urbit
paths, see the filesystem section.)
Generators (files in /gen) are run with +:
~your-urbit:dojo> +hello 'world'
Save output to a file in %clay with *:
~your-urbit:dojo> *some/file/path/hoon 'hello world'
Run system commands from :hood, like reload, using |:
~your-urbit:dojo> |reload %eyre
Generators
Generators are short Hoon scripts, saved as .hoon files in the /gen
directory. Many Dojo commands exist in the form of generators. The syntax for
running a generator is +genname for a generator saved as genname.hoon.
+cat
Accepts a path and displays the file. Similar to Unix cat.
~your-urbit:dojo> +cat %/gen/curl/hoon
+code
Generates a code that is used to remotely log into your ship. No arguments.
~your-urbit:dojo> +code
+curl
Retrieves data from a URL. Accepts a tape. Similar to Unix curl.
~your-urbit:dojo> +curl "http://nyt.com"
+hello
Just prints the argument. Accepts a @ta.
~your-urbit:dojo> +hello 'mars'
+ls
Similar to Unix ls. Accepts a path.
~your-urbit:dojo> +ls %/gen
~your-urbit:dojo> +ls /~talsur-todres/home/2/gen/program
+solid
Compile the current state of the kernel and output a noun. Usually downloaded to a file in unix. No arguments.
~your-urbit:dojo> .urbit/pill +solid
+test
Testrunner. Can test multiple generators at once, conventionally ones
in the /test folder. Takes a path.
~your-urbit:dojo> +test /lib
+ticket
Generate a ticket for an urbit ship. Takes an urbit name (@p).
~your-urbit:dojo> +ticket ~talsur-todres-your-urbit
+tree
Generate a recursive directory listing. Takes a path.
~your-urbit:dojo> +tree %/sys
Hood
The hood is the system daemon. See gen/hood and app/hood.
|hi - Sends a direct message. Sort of like Unix write. Accepts
an urbit name (@p) and a string (tape, which is text wrapped with double-quotes).
~your-urbit:dojo> |hi ~binzod "you there?"
|link / |unlink - Link / unlink a remote app. Accepts an
Urbit name and an app name.
~your-urbit:dojo> |link ~talsur-todres %octo
|mass - Prints the current memory usage of all the kernel modules.
No arguments.
~your-urbit:dojo> |mass
|reload - Reloads a kernel module (vane) from source. Accepts any
number of vane names.
~your-urbit:dojo> |reload %clay %eyre
|reset - Reloads hoon.hoon and all modules. No arguments.
~your-urbit:dojo> |reset
|start - Starts an app. Accepts an app name.
~your-urbit:dojo> |start %curl
Dojo manual
Sources and sinks
A Dojo command is either a source or a sink. A source is just something that can be printed to your console or the result of some computation. A sink is an effect: a change to the filesystem, a network message, a change to your environment, or a typed message to an app.
Sources can be chained together, but we can only produce one effect per command.
Sinks
= - Set variable
Set any environment variable:
~your-urbit:dojo> =foo 42
~your-urbit:dojo> (add 2 foo)
44
Make sure to note that =var is Dojo syntax, not Hoon syntax. You cannot bind a
variable in a .hoon file in this way.
Special variables
There are a few special variables that the Dojo maintains.
: - Send to app
:app goes to a local app, :~ship/app goes to the app on ~ship.
Send a helm-hi message to hood:
~your-urbit:dojo> :hood &helm-hi 'hi'
Apps usually expect marked data, so & is often used here.
* - Save in %clay
Save a new .hoon file in gen:
~your-urbit:dojo> *%/gen/foo/hoon '# hello'
The last component of the path is expected to be the mark (or mime type).
. - Export to Unix
Export a noun to Unix with .:
~your-urbit:dojo> .foo/bar/baz (add 2 2)
Which creates a file at pier/.urb/put/foo/bar.baz.
This is very often used with +solid:
~your-urbit:dojo> .urbit/pill +solid
Which outputs a new urbit.pill to pier/.urb/put/urbit.pill
Sources
& - Mark conversion
Convert between marks using &, with the destination mark first. You can stack multiple mark conversions together, and some marks can only be converted to specific other marks. In this example, Udon is converted to &hymn (a mark which supplies the html, head, body, and closing tags) first, before being converted to HTML:
~your-urbit:dojo>&html &hymn &udon ';h1#hello: hello'
'<html><head></head><body><h1 id="hello">hello</h1></body></html>'
Performing a conversion straight from Udon to the &hymn mark reveals a bit more about its mark conversion:
~your-urbit:dojo>&hymn &udon ';h1#hello: hello'
[[%html ~] [[%head ~] ~] [[%body ~] [g=[n=%h1 a=~[[n=%id v="hello"]]] c=~[[g=[n=%$ a=~[[n=%$ v="hello"]]] c=~]]] ~] ~]
As does converting straight from Udon to HTML:
~your-urbit:dojo>&html &udon ';h1#hello: hello'
';h1#hello: hello'
_ - Run a function
Use _ to run a gate (or function):
Write an arbitrary function and pass data to it:
~your-urbit:dojo> _|=([a=@] (mul a 3)) 3
9
Use a function to get the status code from an http request:
~your-urbit:dojo> _|=([p=@ud q=* r=*] p) +http://google.com
301
+ - - HTTP requests
+http[s]://example.com - sends a GET request
+http[s]://example.com &json [%s 'hi'] - sends a POST request with the
JSON "hi" in the body.
-http[s]://example.com &json [%s 'hi'] - sends a PUT request with the
JSON "hi" in the body.
Note that the first of these is a source while the last two are sinks.
+ - Generators
Generators are simple Hoon scripts loaded from the filesystem. They live
in gen/.
An example of a generator that is built into your urbit is +code. It produces
the code needed to log into your ship remotely.
~your-urbit:dojo> +code
fintyr-haldet-fassev-solhex
Variables
You can use = to set an environment variable in Dojo, but there are
a few reserved names that have special uses.
dir
Current working %clay desk and revision. Read / write.
Examples:
~your-urbit:dojo> =dir %/gen
~your-urbit:dojo> +ls %
404/hoon docs/ dojo/hoon lib/ listen/hoon md static/udon talk/ testing/udon tree/main/ unmark/ womb/
lib
Current set of libraries (/lib) in your environment. Can be set
with /+. Read / write.
Examples:
~your-urbit:dojo> /+ number-to-words
Now we can use arms from lib/number-to-words.hoon
~your-urbit:dojo> (to-words:eng-us:number-to-words 123.456)
sur
Current set of structures (/sur) in your environment. Can be set
with /-. Read / write.
Examples:
~your-urbit:dojo> /- sole
Now we can use arms in sur/sole.hoon.
~your-urbit:dojo> `sole-effect:sole`[%bel ~]
now
The current (128-bit @da) time. Read-only.
Example:
~your-urbit:dojo> now
~2016.3.21..21.10.57..429a
our
The current urbit ship. Read-only.
Example:
~your-urbit:dojo> our
~your-urbit
eny
512 bits of entropy. Read-only.
Example:
~your-urbit:dojo> eny
\/0vnt.d474o.gpahj.jcf3o.448fh.2lamb.82ljm.8ol8u.b02vi.mrvvp.b7et2.knb7m.l8he\/
8.8qb9s.drm36.77n9b.a0qst.30g03.l5lb5.nvsbc.v39tn
\/
Troubleshooting
If you encounter %dy-edit-busy while entering commands, it is
because your Dojo is blocked on a timer or an HTTP request. Type backspace
and your Dojo will end the blocked command.
Filesystem
Urbit has its own revision-controlled filesystem, Clay. Clay is a typed, global,
referentially transparent namespace. An easy way to think about it is like typed
git.
The most common way to use Clay is to mount a Clay node in a Unix directory. The mounted directory is always at the root of your pier directory.
Quickstart
This quick-start guide will walk you through some common commands. Follow along
using your Dojo. When you get a >= message after entering a command, this means
that the command was successful.
It's important to note that whenever you want to sync changes from your Unix
directory to your ship, you must use the |commit %desk command, where %desk
is the desk that you'd like to sync to.
When developing it's a good idea to use a separate desk. Create a %sandbox
desk based on the %home desk:
~your-urbit:dojo> |merge %sandbox ~your-urbit %home
Running our produces your ship-name, meaning that you can run the following
command instead of typing out the entire thing. Useful for comets due to their
very long names.
~your-urbit:dojo> |merge %sandbox our %home
Most of the time we want to use Clay from Unix. Mount the entire contents of
your sandbox desk to Unix:
~your-urbit:dojo> |mount /=sandbox=
To explore the filesystem from inside Urbit +ls and +cat are useful. +ls
displays files in the current directory, and +cat displays the contents of
a file.
We can use % to mean "current directory." The result of the command below
is just like using ls in a Unix terminal.
~your-urbit:dojo> +ls %
Notice how +cat % does the same thing. That's because everything in Clay,
including directories, is a file.
Sync from your friend ~some-ship's %experiment desk to your
%sandbox desk:
~your-urbit:dojo> |sync %sandbox ~some-ship %experiment
If and when your sync is successful, you will receive a message:
activated sync from %experiment on ~some-ship to %sandbox
The ship that you sync from will get their own message indicating that you're both connected as peers:
; ~your-urbit is your neighbor.
Clay manual
Paths
A path in Clay is a list of URL-safe text, restricted to the characters
[a z],[0 9], ., -, _, and ~. Formally this is a (list knot),
meaning that each segment, delineated by /, is of the knot ASCII-text type.
In other words, paths are expressed as /foo/bar/baz. File extensions are
separated from file names with /, not .. Extensions are syntactically
identical to subdirectories, except that they must terminate the path.
Paths begin with a piece of data called a beak. A beak is formally a
(p=ship q=desk r=case); it has three components, and might look like
/~dozbud-namsep/home/11.
The first beak component is ship, which is, as you might guess, the name of
an Urbit ship. The second component is desk, which is a workspace meant to
contain other directories; the default desk is %home. The third component is
case, which represents version information in various ways: date and time;
a version sequence, which is a value incremented by one whenever a file on the
given desk is modified; or an arbitrary plaintext label.
You can find what your beak is at any given moment by
typing % in the Dojo and looking at the first three results.
We use beaks because, unlike the current internet, the Urbit network uses a
global namespace. That means that a file named example.hoon in the /gen
directory on the %home desk of your ship ~lodleb-ritrul would have a
universal address to anyone else on the network:
/~lodleb-ritrul/home/186/gen/example/hoon. That, of
course, doesn't mean that everyone on the network has privileges to access that
path.
The structure that combines a beak with further path information is called a
beam.
Relative paths
The % command, which we gestured at in the above section, represents the
relative path, which is the path where you are currently working. If your
working directory is just your home desk, indicated by the
prompt ~your-planet:dojo>, then running the command below will print your
working directory's beam information: your beak, and a ~ that represents
the empty list since no path is present.
~your-urbit:dojo> %
%s can be stacked to indicate one level further up in the hierarchy for each
additional %. Try the following command:
~your-planet:dojo> %%%
You'll probably notice that it only has your ship name and the empty list. The
two additional %s abandoned the case and the desk information by moving
up twice the hierarchy.
There are no local relative paths. /foo/bar must be written as
%/foo/bar.
Substitution
You don't need to write out the explicit path every time you want to reference
somewhere outside of your working directory. You can substitute = for the
segments of a path.
Recall that a full address in the the Urbit namespace is a beam: the
/ship/desk/case/path. If you've switched to another desk before, you're
already familiar with substitution syntax:
~your-urbit:dojo> =dir /=sandbox=
The above command uses substitution to use your current ship and
case; only the desk argument, which is located between the other two, is
given something new. Without substitution, you would need to write:
~your-urbit:dojo> =dir /~your-urbit/sandbox/85
Substitutions work the same way in beaks (the ship/desk/case part) and
paths. For example, if you are in the /gen directory, you can reference a file
in the /app directory like below. (+cat displays the contents of a file).
~your-urbit:dojo> =dir %/gen
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen> +cat /===/app/curl/hoon
Note what was substituted out, and note that we don't need to separate = with
/.
If we changed our working directory to something called /gen/gmail, we could
access a file called
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen> =dir %/gmail
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen/gmail> +cat /===/app/=/split/hoon
Because both paths share a directory named /gmail at the same position in the
address hierarchy – which, if you recall, is just a list – the above command
works!
We can do the same thing between desks. If %sandbox has been merged with
%home, the following command will produce the same results as the above
command.
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen/gmail> +cat /=sandbox=/app/=/split/hoon
Most commonly this is used to avoid having to know the current revision
number in the dojo: /~lodleb-ritrul/home/~2018.10.2..00.35.44..d7e8/gen/example/hoon
Changing directories
Change the working directory with =dir. It's our equivalent of the Unix cd.
For example, the syntax to navigate to /home/gen/ask is:
~your-urbit:dojo> =dir /=home=/gen/ask
This command will turn your prompt into something like this:
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen/ask>
Using =dir without anything else uses the null path, which returns you to
your home desk.
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen/ask> =dir
Your dojo prompt will turn back into ~your-urbit:dojo>.
To go up levels in the path hierarchy, recall the relative path expression
%. Stacking them represents another level higher in the hierarchy than
the current working directory for each % beyond the initial. The command below
brings you one level up:
~your-urbit:dojo> =dir %/gen
~your-urbit:dojo/=/=/~2018.10.2..00.35.44..d7e8/gen> =dir %%
Revision-control
Mount
Syntax: |mount /clay/path [Unix-name]
Mount the clay-path at the Unix mount point Unix-name.
Examples:
|mount %/gen generators
Mounts %/gen to /generators inside your pier directory.
Unmount
|unmount [clay-path || Unix-name]
Unmount the path or name from Unix.
Examples:
|unmount %/gen
Unmounts the Clay path %/gen from whatever name it was mounted as.
|unmount %generators
Unmounts the Unix path /generators.
Merge
|merge desk beak[, =gem strategy]
Merges a beak into a desk using an optional merge strategy.
A beak is a ship-desk-case triple, encoded as a
path(/~dozbud/home/2)
Examples:
|merge %home-work /=home=, =gem %fine
Merge /=home= into %home-work using merge strategy %fine.
|merge %examples ~wacbex-ribmex %examples
Merge the %examples desk from ~waxbex-ribmex
Sync
|sync desk plot [plot-desk]
Subscribe to continuous updates from remote plot on local desk.
plot-desk can specify the remote desk name. When omitted it defaults
to being the same as desk. Non-comet urbits have
|sync %home ~parent %kids automatically set up (where ~parent is the
planet that issued a moon, the star that issued a planet, or the galaxy
that issued a star).
Examples:
|sync %home-local ~dozbud %home
|sync %home ~doznec
Unsync
|unsync desk plot [plot-desk]
Unsubscribe from updates from remote plot on local desk with
optional plot-desk. Arguments must match original |sync command.
Example:
|unsync %home-local ~dozbud %home
Label
|label desk name
Label the current version of desk name.
Example:
|label %home release
Merge strategies
%init - used if it's the first commit to a desk. Also can be used to
"reinitialize" a desk – revision numbers keep going up, but the new
revision isn't necessarily a descendent of the previously numbered
version, allowing merges to be rerun.
%this - keep what's in Bob's desk, but join the ancestry.
%that - take what's in Alice's desk, but join the ancestry. This is
the reverse of %this. This is different from %init because the new
commit has both sides in its ancestry.
%fine - "fast-forward" merge. This succeeds if and only if one head is in the
ancestry of the other.
%meet, %mate, and %meld - find the most recent common ancestor to
use as our merge base.
A %meet merge only succeeds if the changes from the merge base to
Alice's head (hereafter, "Alice's changes") are in different files than
Bob's changes. In this case, the parents are both Alice's and Bob's
heads, and the data is the merge base plus Alice's changed files plus
Bob's changed files.
A %mate merge attempts to merge changes to the same file when both
Alice and Bob change it. If the merge is clean, we use it; otherwise, we
fail. A merge between different types of changes – for example,
deleting a file vs changing it – is always a conflict. If we succeed,
the parents are both Alice's and Bob's heads, and the data is the merge
base plus Alice's changed files plus Bob's changed files plus the merged
files.
A %meld merge will succeed even if there are conflicts. If there are
conflicts in a file, then we use the merge base's version of that file,
and we produce a set of files with conflicts. The parents are both
Alice's and Bob's heads, and the data is the merge base plus Alice's
changed files plus Bob's changed files plus the successfully merged
files plus the merge base's version of the conflicting files.
%auto - meta-strategy. Check to see if Bob's desk exists, and if it
doesn't we use an %init merge. Otherwise, we progressively try
%fine, %meet, and %mate until one succeeds. If none succeed, we
merge Bob's desk into a scratch desk. Then, we merge Alice's desk into
the scratch desk with the %meld option to force the merge. Finally, we
annotate any conflicts, if we know how.
Manipulation
+cat
Syntax: +cat path [path ...]
Similar to Unix cat. +cat takes one or more paths, and prints their
contents. If that path is a file, the contents of the file is printed. If the
path terminates in a directory, the list of names at that path is produced.
+ls
Syntax: +ls path
Similar to Unix ls. +ls takes a single path.
Produces a list of names at the path.
~your-urbit:dojo> +cat %/our/home/gen/curl/hoon
|rm
Syntax: |rm path
Remove the data at path. Path must be a path to the actual node, not a
'directory'.
|cp
Syntax: |cp to from
Copy the file at from into the path to.
|mv
Syntax: |mv to from
Move the file at from into the path to.
In Clay, |mv is just a shorthand for |cp then |rm. The |rm
doesn't happen unless the |cp succeeds.