Archive for January, 2010

Connect to remote erlang shell while inside emacs

Thursday, January 7th, 2010

While developing my top secret project, I have been getting into the fun stuff in Erlang and Emacs. Connecting to a running instance of my app from a remote shell wasn’t straightforward to me at first, so below is my documented way of connecting, as well as dropping into the Erlang JCL from within an Emacs erlang shell.

  1. Start yaws: yaws –daemon -sname appname –conf /path/to/yaws.conf
  2. Start emacs, and from within emacs start an Erlang shell with C-c C-z (assuming you have distel configured).
  3. From the Emacs erlang shell, get into Erlang’s JCL by typing C-q C-g and pressing enter. A ^G will be printed at the prompt, but won’t be evaluated until you press enter. You should see the familiar JCL prompt “User switch command –>”.
  4. Type ‘j’ to see current jobs you have running locally, which is probably just the current shell (1 {shell,start,[init]}).
  5. Type ‘r appname@compy’ to connect to the remote node identified by appname ( from the -sname parameter ) on the computer compy (usually whatever hostname returns)
  6. Type ‘j’ to see current jobs, which should list your current shell as “1 {shell,start,[init]}”, and a second shell “2* {appname@compy,shell,start,[]}”.
  7. Type ‘c 2′ to connect to the remote shell. You can now run commands in the node’s shell. You may have to press enter again to bring up a shell prompt.
james@compy 14:33:34 ~/dev/erlang/app
> yaws --daemon -sname app --conf config/yaws.conf
 
james@compy 14:34:00 ~/dev/erlang/app
> emacs
Eshell V5.7.4  (abort with ^G)
1> ^G
 
User switch command
 --> j
   1* {shell,start,[init]}
 --> r app@compy
 --> j
   1  {shell,start,[init]}
   2* {app@compy,shell,start,[]}
 --> c 2
 
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