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1---

2next: true

3sort: 5

4title: Shell (:dojo)

5---

7# Shell (`:dojo`)

9<div class="row">

10<div class="col-md-8">

12The `:dojo` is the place to quickly experiment with Urbit. On

13the surface the `:dojo` is just a Hoon REPL. On the inside, the

14`:dojo` is a system for operating on and transforming data in

15Urbit.

17</div>

18</div>

20## Quickstart

22Evaluate a hoon expression:

24 ~your-urbit:dojo> (add 2 2)

25 ~your-urbit:dojo> %+ add 2 2

27Tall form Hoon may require multiple lines:

29 ~your-urbit:dojo> %+ add

30 ~your-urbit:dojo< 2

31 ~your-urbit:dojo< 2

33Use `=var` to save a shell variable:

35 ~your-urbit:dojo> =foo (add 2 2)

37Use `=dir` to set the current working directory:

39 ~your-urbit:dojo> =dir %/web

41Generators (files in `/gen`) are run with `+`:

43 ~your-urbit:dojo> +hello 'world'

45Save output to a file in `%clay` with `*`:

47 ~your-urbit:dojo> *some/file/path/hoon 'hello world'

49Run system commands from `:hood`, like `reload`, using `|`:

51 ~your-urbit:dojo> |reload %eyre

54### Generators

56**`+cat`** - Similar to Unix `cat`. Accepts a path.

58 ~your-urbit:dojo> +cat %/web/md

59 ~your-urbit:dojo> +cat /~talsur-todres/home/2/web/notes/md

61**`+curl`** - Similar to Unix `curl`. Accepts a `tape`.

63 ~your-urbit:dojo> +curl "http://nyt.com"

65**`+hello`** - Just prints the argument. Accepts a `@ta`.

67 ~your-urbit:dojo> +hello 'mars'

69**`+ls`** - Similar to Unix `ls`. Accepts a path.

71 ~your-urbit:dojo> +ls %/web

72 ~your-urbit:dojo> +ls /~talsur-todres/home/2/web/notes

74**`+moon`** - Generate a random moon from a planet. No arguments.

76**`+solid`** - Compile the current state of the kernel and output a noun. Usually downloaded to a file in unix. No arguments.

78 ~your-urbit:dojo> .urbit/pill +solid

80**`+ticket`** - Generate a ticket for an Urbit plot. Takes an Urbit name (`@p`).

82 ~your-urbit:dojo> +ticket ~talsur-todres-your-urbit

84**`+tree`** - Generate a recursive directory listing. Takes a path.

86 ~your-urbit:dojo> +tree %/web

88### Hood

90The hood is the system daemon. See `gen/hood` and `app/hood`.

92**`|hi`** - Sends a direct message. Sort of like Unix `write`. Accepts an urbit name (`@p`) and a string (`cord`).

94 ~your-urbit:dojo> |hi ~doznec 'you there?'

96**`|link`** / **`|unlink`** - Link / unlink a remote app. Accepts an Urbit name and an app name.

98 ~your-urbit:dojo> |link ~talsur-todres %octo

100**`|mass`** - Prints the current memory usage of all the kernel modules. No arguments.

101

102**`|reload`** - Reloads a kernel module (vane) from source. Accepts any number of vane names.

103

104 ~your-urbit:dojo> |reload %clay %eyre

105

106**`|reset`** - Reloads `hoon.hoon`. No arguments.

107

108**`|start`** - Starts an app. Accepts an app name.

109

110 ~your-urbit:dojo> |start %curl

111

112## Manual

113

114<h3 class="first child">Sources and sinks</h3>

115

116A 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 typed message to an app.

117

118Sources can be chained together, but we can only produce one effect per command.

119

120### Sinks

121

122#### `=` - Set variable

123

124Set any envronment variable:

125

126 ~your-urbit:dojo> =foo 42

127 ~your-urbit:dojo> (add 2 foo)

128