How to manually send a message to a process which I just spawned?

Question

How can I send a message to process with Erlang? I did start a process and the output shows me that the pid (process identifier) is <0.39.0>. My question is how can I send a message to this process (<0.39.0>) manually.

Answer 1

While list_to_pid/1 can indeed be used to construct a PID and use it to send messages its usage is discouraged:

This BIF is intended for debugging and for use in the Erlang operating system. It should not be used in application programs.

A better approach would be to save the PID when you start the process:

1> P = spawn(fun() -> receive _ -> ok end end).
<0.34.0>
2> P!hi.
hi

Answer 2

(emacs@yus-iMac.local)100> P = list_to_pid("<0.39.0>").
<0.39.0>
(emacs@yus-iMac.local)101> P!aaa.
aaa

Answer 3

Besides other solution,REGISTER func maybe helpful.

    register(regpid,spawn(fun() -> receive _ ok end end).
    regpid ! msg.

you can send msg to regpid everywhere.