Getting two erl shells to talk on OS X

Question

I want to be able to have two Erlang shells to talk. I'm running on OS X.

I tried the tut17 example here.

I've also tried:

$ erl -sname foo

and then in a new Terminal:

$ erl -sname bar

(bar@elife)1> net_adm:ping(foo@elife).
pang

Any ideas?

Answer 1

It's kind of broken on the mac. By default, the mac can't resolve its own shortname. Your host's name is really probably "elife.local".

If you start erl with -name FQDN, then the pings will work.

ie: you would start it with

$ erl -name foo@elife.local

this probably could be fixed by making the mac capable of resolving it's own short name

Here's example output from my mac. When I do -sname I get the same result as you.

The first node:

$ erl -name foo@mookie.local
Erlang R13B03 (erts-5.7.4) [source] [smp:2:2] [rq:2] [async-threads:0] [kernel-poll:false]

Eshell V5.7.4  (abort with ^G)
(foo@mookie.local)1> 

The other node:

$ erl -name bar@mookie.local
Erlang R13B03 (erts-5.7.4) [source] [smp:2:2] [rq:2] [async-threads:0] [kernel-poll:false]

Eshell V5.7.4  (abort with ^G)
(bar@mookie.local)1> net_adm:ping('foo@mookie.local').
pong

Answer 2

A simpler fix might just be editing your /etc/hosts file and make sure you have something like this line:

127.0.0.1 localhost elife

My mac works fine with shortnames, and I believe this is what did it.

Answer 3

For the nodes communicate with each other, both should have the same cookie. On the same box it works as it end up using the cookie from $HOME/.erlang.cookie file. If this file is not present, it create a new file and put some random cookie in it. Future shells use the same cookie. But it is always better to specify the cookie on the command line via setcookie parameter.

erl -name node1@foo.local -setcookie mycookie