Julia installation is straightforward, whether using precompiled binaries or compiling from source. Download and install Julia by following the instructions at http://julialang.org/downloads/.
The easiest way to learn and experiment with Julia is by starting an interactive session (also known as a read-eval-print loop or "repl"):
$ julia
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_ _ _(_)_ |
(_) | (_) (_) | A fresh approach to technical computing.
_ _ _| |_ __ _ |
| | | | | | |/ _` | | Version 0 (pre-release)
| | |_| | | | (_| | | Commit 61847c5aa7 (2011-08-20 06:11:31)*
_/ |\__'_|_|_|\__'_| |
|__/ |
julia> 1 + 2
3
julia> ans
3
To exit the interactive session, type ^D — the control key
together with the d key or type quit(). When run in interactive
mode, julia displays a banner and prompts the user for input. Once
the user has entered a complete expression, such as 1 + 2, and
hits enter, the interactive session evaluates the expression and shows
its value. If an expression is entered into an interactive session
with a trailing semicolon, its value is not shown. The variable
ans is bound to the value of the last evaluated expression whether
it is shown or not. The ans variable is only bound in interactive
sessions, not when Julia code is run in other ways.
To evaluate expressions written in a source file file.jl, write
include("file.jl").
To run code in a file non-interactively, you can give it as the first argument to the julia command:
$ julia script.jl arg1 arg2...
As the example implies, the following command-line arguments to julia
are taken as command-line arguments to the program script.jl, passed
in the global constant ARGS. ARGS is also set when script code
is given using the -e option on the command line (see the julia
help output below). For example, to just print the arguments given to a
script, you could do this:
$ julia -e 'for x in ARGS; println(x); end' foo bar foo bar
Or you could put that code into a script and run it:
$ echo 'for x in ARGS; println(x); end' > script.jl $ julia script.jl foo bar foo bar
Julia can be started in parallel mode with either the -p or the
--machinefile options. -p n will launch an additional n
worker processes, while --machinefile file will launch a worker
for each line in file file. The machines defined in file must be
accessible via a passwordless ssh login, with Julia installed at the
same location as the current host. Each machine definition takes the form
[user@]host[:port]
If you have code that you want executed whenever julia is run, you can
put it in ~\.juliarc.jl:
$ echo 'println("Greetings! 你好! 안녕하세요?")' > ~/.juliarc.jl
$ julia
Greetings! 你好! 안녕하세요?
...
There are various ways to run Julia code and provide options, similar to
those available for the perl and ruby programs:
julia [options] [program] [args...] -v --version Display version information -h --help Print this message -q --quiet Quiet startup without banner -H --home=<dir> Load files relative to <dir> -T --tab=<size> Set REPL tab width to <size> -e --eval=<expr> Evaluate <expr> -E --print=<expr> Evaluate and show <expr> -P --post-boot=<expr> Evaluate <expr> right after boot -L --load=file Load <file> right after boot on all processors -J --sysimage=file Start up with the given system image file -p n Run n local processes --machinefile file Run processes on hosts listed in file --no-history Don't load or save history -f --no-startup Don't load ~/.juliarc.jl -F Load ~/.juliarc.jl, then handle remaining inputs --color=yes|no Enable or disable color text --check-bounds=yes|no Emit bounds checks always or never (ignoring declarations)
In addition to this manual, there are various other resources that may help new users get started with julia: