Checking if a process with a certain pid is running

gistfile1.rb

# Sometimes, specially if we are building a monitoring system or an admin UI, 
# we need to be able to easily check if a process is running. 
# Unfortunately this is not directly available through Process module. so here is a patch to add it
#
# Usage:   
# Process.running?(pid)     
# Process.memory(pid)     # returns the memory usage in KB


module Process 
  def self.running?(pid)
    return false if pid.nil?
    begin 
      Process.kill(0, pid.to_i)
      return true
    rescue Errno::ESRCH
      return false
    end
  end

  def self.memory(pid=nil)
    pid ||= Process.pid
    x=`ps ax -o pid,rss | grep -E "^[[:space:]]*#{pid}"`.strip.split.last
    x.to_i/1024    
  end
end