[rabbitmq-discuss] RabbitMQ - 3.0.0 multi node with detach command

Simon MacMullen simon at rabbitmq.com
Thu Dec 6 10:38:05 GMT 2012

On 06/12/12 10:05, PONMUTHU M wrote:
> hi,
>     i read in website, detached key can used to start multiple nodes in same
> machine after load the new environment (node & port)
>     but when i use that am getting the following error
>     [root at RMQ-NIV-T2 ~]# RABBITMQ_NODE_PORT=5676
>     /usr/sbin/rabbitmq-server -detached
>     Warning: PID file not written; -detached was passed.

That's a warning, not an error. It's just telling you that we don't 
write a PID file when -detached is passed, since we're unable to 
determine the PID early enough to make it useful.

>   if i use " rabbitmq-server & "(after load new node & port) instead of
> detached , new node getting started .
>   now my question is .
>   what is the difference between detached & start the rabbitmq service in
> different environment.

"-detached" tells Erlang to fork the process.

"&" tells the shell to fork the process.

>   if both are same . which types is recommended to follow in server level

The only difference is that you get a PID file with "&", which then lets 
you use "rabbitmqctl wait" to make sure you know when the server has 
finished starting. That's what the init.s scripts for our .deb and RPM 
packages do.

Of course, I would recommend that you use those packages rather than 
sorting this out yourself, if you possibly can.

Cheers, Simon

Simon MacMullen
RabbitMQ, VMware

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