# What is Erlang?

Erlang is a programming language used to build massively scalable soft real-time systems with requirements on high availability. Some of its uses are in telecoms, banking, e-commerce, computer telephony and instant messaging. Erlang's runtime system has built-in support for concurrency, distribution and fault tolerance.

> [wikipedia.org/wiki/Erlang_(programming_language)](https://en.wikipedia.org/wiki/Erlang_%28programming_language%29)

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# How to use this image

## Run it as the REPL

```console
➸ docker run -it --rm erlang
Erlang/OTP 20 [erts-9.0] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V9.0  (abort with ^G)
1> uptime().
3 seconds
ok
2>                                 % use Ctrl+G to call the shell switch
User switch command
 --> ?
  c [nn]            - connect to job
  i [nn]            - interrupt job
  k [nn]            - kill job
  j                 - list all jobs
  s [shell]         - start local shell
  r [node [shell]]  - start remote shell
  q                 - quit erlang
  ? | h             - this message
 --> q
➸ docker run -it --rm -h erlang.local erlang erl -name snode@erlang.local
Erlang/OTP 20 [erts-9.0] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V9.0  (abort with ^G)
(snode@erlang.local)1> erlang:system_info(otp_release).
"20"
(snode@erlang.local)2>
User switch command
--> q
```

## Run a single Erlang escript

```console
$ docker run -it --rm --name %%REPO%%-inst1 -v "$PWD":/usr/src/myapp -w /usr/src/myapp %%REPO%% escript your-escript.erl
```