Write out worker pid to PIDFILE if specified.

README.markdown

@@ -235,6 +235,13 @@ variable.
 
     $ VVERBOSE=1 QUEUE=file_serve rake environment resque:work
 
+### Process IDs (PIDs)
+
+There are scenarios where it's helpful to record the PID of a resque
+worker process.  Use the PIDFILE option for easy access to the PID:
+
+    $ PIDFILE=./resque.pid QUEUE=file_serve rake environment resque:work
+
 
 ### Priorities and Queue Lists
 

lib/resque/tasks.rb

@@ -8,7 +8,6 @@
   task :work => :setup do
     require 'resque'
 
-    worker = nil
     queues = (ENV['QUEUES'] || ENV['QUEUE']).to_s.split(',')
 
     begin
@@ -19,6 +18,10 @@
       abort "set QUEUE env var, e.g. $ QUEUE=critical,high rake resque:work"
     end
 
+    if ENV['PIDFILE']
+      File.open(ENV['PIDFILE'], 'w') { |f| f << Process.pid.to_s }
+    end
+
     worker.log "Starting worker #{worker}"
 
     worker.work(ENV['INTERVAL'] || 5) # interval, will block